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Chapter Outline
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Learning Objectives
After studying this chapter, you should be able to do the following:
1. Examine contributing factors to longevity and life expectancy and distinguish between them.
2. Identify and distinguish between theories of primary aging.
3. Recognize visible changes that take place during adulthood.
4. Appreciate changes in adult sexuality.
5. Describe adult changes in the primary senses.
6. Recognize common age-related diseases and explain factors that contribute to their development.
7. Explain the most common degenerative diseases of the brain and distinguish between them.
Physical Health and Development
4
Introduction
4.1 Theories of Primary Aging • Programmed Theories • Damage Theories • The Fountain of Youth?
4.2 Visible Changes in Adulthood • Skin • Hair • Body Build, Bones, and Mobility • Respiratory System
4.3 Sexual Changes • Women • Men • Reproduction • Desire
4.4 Changes in the Senses • Vision • Hearing • Taste and Smell
4.5 Disease in Adulthood • Sexually Transmitted Infections and Diseases • Respiratory Disease • Osteoporosis • Skin Cancer • Diseases of the Cardiovascular System
4.6 Degenerative Diseases of the Brain • Alzheimer’s Disease • Parkinson’s Disease
Chapter Summary
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CHAPTER 4Introduction
Figure 4.1: Life expectancy by country
Life expectancy varies greatly among regions of the world.
Source: Central Intelligence Agency. Country comparison: Life expectancy at birth. The World Factbook. Retrieved April 4, 2013, from Central Intelligence Agency website:
https://www.cia.gov/library/publications/the-world-factbook/ rankorder/2102rank.html
Introduction
We live in a time of great technological and scientific advancement, which has paved the way to discovering how to live more healthily and increase rates of survival. With an ideal medical and social environment, we can approach the maximum years that are genetically programmed into our species. However, throughout the world there are also social and lifestyle factors that impact the number of years we can expect any particular person to live. We refer to this theoretical number as longevity. Biologically, the longevity of humans only changes slightly over many thousands of years. There were very old people 2,000 years ago, and there are very old people today, but we do not actually know how long the “perfect” body in the ideal envi- ronment would live. The longest documented human lifespan was Jeanne Calment, who lived past 122, and many humans are living well past 110 years (GRG, 2012; Robine & Allard, 2003).
On the other hand, life expectancy is the average age of death for a specific population. When infants die during childbirth, gang members die during adolescence, and older people die of natu- ral causes, we include all of these when compiling an estimate of the average life expectancy in a population. Modern sewer installations, understanding of germ theory, and use of antibiotics and immunizations have all significantly contributed to increased life expectancy.
In addition, on average people live longer by avoiding dangerous habits and risky situations, like smoking, drinking and driving, and engaging in unprotected sex. Circumstances are not always avoidable, though. Worldwide, many infants are born into contaminated environments that cause infections. The lack of medical care affects mortality rate (number of deaths) further. Many peo- ple do not have the option of breathing smoke-free air. Individuals of all ages can be subjected to civil unrest and war. Therefore, both personal and social activities affect average life expectancy for a population, which we can define as a community in New Jersey or an entire country. The life expectancy in Afghanistan and in many countries in war-torn Central and South Africa is estimated to be less than 50 years. That figure differs greatly from the one in countries like Canada, Australia, Italy, and Japan, where life expectancy exceeds 80. See Figure 4.1 for a comparison of life expec- tancies between selected countries.
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CHAPTER 4Section 4.1 Theories of Primary Aging
There are further differences among women and men. With only six exceptions (five of which are in sub-Saharan Africa), in every country for which data are available, on average women outlive men, often by a decade or more. In Monaco, for instance, life expectancy for men is nearly 86, but for women it is almost 94. When life expectancy is significantly lower than the worldwide average, the reasons are fairly obvious: War, AIDS, infant deaths, and childhood diseases claim many young lives and devastate the population average. On the other hand, scientists are curious about the differences that exist between those who live in large cities versus small towns, and what factors contribute to differences in life expectancy among different countries like Mexico (77), Russia (66), and France (81).
In the United States, research shows that Blacks, Hispanics, and those in lower income groups have more chronic diseases, poorer health, and a lower life expectancy than those who are in middle- and upper-income brackets. However, if instead people are divided simply into higher-and lower-income brackets, racial differences disappear; income level is the most important factor associated with health, not race (Guralnik, Land, Blazer, Fillenbaum, & Branch, 1993). Of course, income is strongly associated with educational achievement as well, so income and education are usually better predictors of secondary aging than racial variables.
Therefore, in general, both direct and indirect factors influence aging, and this is another issue that we can relate to the difference between nature and nurture. Because longevity is governed by principles of nature, primary aging refers to biological elements of development. It includes natural processes such as the loss of muscle mass and deterioration of the senses. On the other hand, life expectancy is closely aligned with environmental and social variables. Some aging pro- cesses can be accelerated or delayed depending on lifestyle or unavoidable environmental condi- tions, and hence contribute only indirectly as explained earlier. These factors, like a lack of exercise or living next to raw sewage, contribute to secondary aging.
While this chapter will focus mostly on primary aging and its theories, it will become apparent that we cannot always easily separate issues related to secondary aging. For instance, it is not uncom- mon to have achy knees, shoulders, and wrists due strictly to age-related decline in the amount of cushioning material in joints. But football players, workers who engage in repetitive tasks, and others who experience physical trauma are likely to have exaggerated aging effects. So, before the next chapter explores areas of development governed more by secondary aging, let’s take a look at physical health and disease as they relate to primary aging.
4.1 Theories of Primary Aging
By understanding how primary aging takes place, biologists, psychologists, physicians, and others can promote the best possible outcomes for the aging population. Most theories fit into two main categories: programmed aging and damage theories. However, no theory exists that adequately explains the limitations of the human lifespan, despite recent advances in molecular biology and genetics (Kunlin, 2010). Furthermore, various theories may have complex connections. Ultimately, an interactionist perspective may provide the best explanation for why our bodies eventually give out.
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CHAPTER 4Section 4.1 Theories of Primary Aging
Programmed Theories Programmed theories of aging suggest that there are biological and genetic limits to how long we can live. Biochemical changes cause cells to weaken and become unstable. Specific genetic programming may account for age-related conditions like some cancers and changes in memory and psychosocial functions. People who live longer than others may inherit a cell structure that has more potential to regenerate instead of self-destruct (Davidovic et al., 2010; Guarner & Rubio- Ruiz, 2012). It is possible that hormones initiate the action of certain genes being switched on or off, a process that epigenetics may also impact.
Another possibility is that the immune system is specifically programmed to become more vulner- able to disease and hence promote mortality. Indeed, researchers have suggested that immunity to disease peaks during adolescence, during which time (from an evolutionary perspective) we have already been able to produce the next generation (Kunlin, 2010). Nevertheless, scientists have failed to identify the mechanisms by which the destructive processes take place, nor do we have a complete understanding of how they work. For instance, researchers have implicated age- related weakening of the immune system in the onset of Alzheimer’s disease, but not in other age-related conditions like osteoarthritis (Guarner & Rubio-Ruiz, 2012; Rozemuller, van Gool, & Eikelenboom, 2005). And if the immune system were the primary mechanism that influences aging, then it is likely that diseases would be more predictable than they are.
Damage Theories There are a number of damage theories of aging (also known as error theories), but they too have limitations. The wear-and-tear theory makes intui- tive sense, as it compares the body to a machine. The more we use it, the more its “parts” deterio- rate. Repeated use of knee and ankle joints causes those areas to wear out. The number of older people who have lost cartilage in their joints provides sup- port for this theory. However, wear-and-tear theory fails to explain why repeated use often has a positive effect by maintaining flexibility and improving overall health. Adults who more vigorously use their joints through exercise generally outlive people who are more sedentary, even when weight is controlled for (Moore et al., 2012). Pulmonary (lungs) and cardiac (heart) functions improve with more use as well.
One specific damage theory involves a type of by- product that occurs as a result of normal cell metab- olism. Free radicals are electrically charged chemi- cals that build up as a normal part of cell production. Free radicals are especially reactive to exposure to modern-day toxins and everyday occurrences like sunlight, x-rays, pollution, and disease. Over a lifetime, the cumulative effect of free radicals cause cells to deteriorate, malfunction, and become susceptible to disease (Kunlin, 2010; Montine et al., 2011). Researchers have theorized that one
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The poor long-term health of football players is often attributed to the wear- and-tear theory.
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CHAPTER 4Section 4.2 Visible Changes in Adulthood
way to stop this oxidative damage is to consume a diet that is rich in multiple types of antioxidants, like berries, broccoli, red wine, and tea. In theory, antioxidants stop free radicals from doing dam- age and hence slow the processes of primary aging (Brown, 2004; Joseph et al., 1999). Although this theory makes intuitive sense, there are still significant challenges to accepting the idea that limiting free-radical production is essential to reversing the aging process (e.g., Page et al., 2010).
The Fountain of Youth? The evidence for free radical theory fuels the movement to reverse primary aging. In addition to recommending the consumption of foods that contain antioxidants, another area of research focuses on limiting calorie intake. If fewer calories are consumed, there is less cellular activity and hence fewer toxic by-products. In a famous study of laboratory rats that researchers provided with restricted, very low-calorie diets that contained all necessary nutrients, rats lived longer and suffered far fewer diseases than their counterparts that consumed normal diets (McCay, Crowell, & Maynard, 1935). Although this study is often used as a marker for what is possible, in general it is probably not practical to suggest that people restrict their calorie intake by denying themselves the everyday pleasure of eating.
Another alternative is to develop drugs that can mimic the effects of caloric restriction. As our understanding of genetics has grown, scientists have identified more genes that are involved in the self-destructive process (Cuervo, 2008). If drugs can stop the genes from behaving “naturally,” they will slow the aging process. Furthermore, if genes that promote longevity by combating envi- ronmental toxins continue to be identified, then they too can be exploited to keep people “young” and healthy.
Think and Review:
Is it more important for you to delay the effects of primary aging (and to find the proverbial “Fountain of Youth”) or to prevent the effects of secondary aging?
4.2 Visible Changes in Adulthood
Once we enter adulthood, observable changes begin to take place no matter what we do, beginning around age 30. Aging skin loses moisture and fats, making it dryer. It will even-tually become thinner, splotchy, and wrinkled. Hair turns gray and thins. We lose muscle mass and strength, along with the ability to perform the same kinds of physical work. Coordina- tion and balance become affected as well. Sight, smell, taste, and hearing all diminish. Many peo- ple have achy joints, and bones may become thinner and weaker. These measureable changes are all a normal part of biological aging, but that does not mean that the news is all bad. Importantly, for the most part, the physical changes that begin in early adulthood do not become particularly noticeable until middle adulthood. In addition, these physical changes are often accompanied by peak psychosocial and cognitive development, often overshadowing and compensating for the physical declines. Let’s look further at the larger changes that are more apparent than the changes that happen within cells and genes.
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CHAPTER 4Section 4.2 Visible Changes in Adulthood
Skin When people try to guess a person’s age, they often look for the most visible signs—wrinkles, gray hair, and, in men especially, hair loss. The same processes that contribute to loss of blood vessels and muscle mass also contribute to a gradual wrinkling of the skin. The skin can be described in three layers, the outer layer (epidermis) that serves mostly as a cover, a middle layer (dermis), and an inner layer made up of a large amount of fat. Unnoticeable at first, there is a gradual loss of elasticity due to the skin’s loss of collagen in the middle layer that provides strength and flexibility. Without it, the skin sags. Oil glands become less active, the layer of fat thins, and skin cells do not hold as much water as before, creating a dry feeling.
Later, the epidermis loses its structure, becomes more transparent, and develops “age spots,” or irregular areas of dark pigment. The thinning of the skin also makes it more difficult for older people to regulate temperature. Even though it may at first be unnoticeable, smoking exacerbates the aging of the skin. This phenomenon is especially apparent around
the mouth. Exposure to the ultraviolet rays of the sun (and artificial tanning lights) also accelerates damage to the skin. Injury due to the sun is magnified in people with lighter skin, and a reduction in pigmentation makes spots more visible (Rexbye et al, 2006).
Hair If people live long enough, eventually hair thins and loses color, although there are tremendous individual, sex, and racial differences (Tobin, Hordinsky, & Bernard, 2005; Van Neste & Tobin, 2004). Though hair appears gray, its hue comes from a mixture of natural pigmentation and the lack of pigmentation; ultimately it loses all color and appears completely white. On average, Afri- cans begin graying in their mid-forties, Asians in their late-thirties, and Whites in their mid-thirties. On average, about 50% of people are 50% gray by 50 years old (Keough & Walsh, 1965).
About 95% of all men but only 20% of all women experience hair loss that is age related. Men tend to lose hair more rapidly than women, including body hair. Additionally, during middle age both men and women may begin to grow more hair in unwanted places. Men often grow hair inside the ears and nose. Depending on individual hormonal changes, about 40% of women have a marked increase in facial hair, most commonly on the chin and above the upper lip. From a psychosocial perspective, women in both developed countries and those within emerging economies often associate excess hair with a lack of femininity, which sometimes impacts confidence and self- image. (Blume-Peytavi, 2011; Sundararaman, Shweta, & Sridhar, 2008).
The overall good news is that even though facial wrinkles and the loss and graying of hair are both definitive visual markers for aging, there is virtually no relationship between them and mortality.
iStockphoto/Thinkstock
In later life, adults experience a loss of elasticity in the skin, leading to wrinkling and sagging.
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CHAPTER 4Section 4.2 Visible Changes in Adulthood
That is, when comparing people of the same ages who have wrinkles or hair loss versus those who do not, there are no differences in longevity (Schnohr, Nyboe, Lange, & Jensen, 1998).
Body Build, Bones, and Mobility In addition to sarcopenia, the gradual loss in muscle mass and strength that begins in the thirties, the body undergoes a number of other changes in stature and composition. For instance, it is clear that people shrink beginning in their fifties. On average, men lose one inch (3 cm) and women nearly two inches (5 cm) before they are 70 years old. Over the next 15–20 years, the loss in stat- ure is doubled (Sorkin, Muller, & Andres, 1999). A compression of bone in the spine, not the discs as some believe, primarily causes the reduction in height (Bennani et al., 2009). In addition, condi- tions like osteoporosis and Parkinson’s disease (discussed later in the chapter) can contribute to even more extreme decreases in height.
On average, weight increases throughout middle adulthood, but it is difficult to know how much is due to maturation and how much is due to lifestyle. We do know that the body naturally burns less energy, and therefore requires fewer calories to maintain a stable weight, but adults also become less active beginning very early in adulthood. If young adults do not exercise and adjust calorie intake, there will be dual factors that contribute to weight gain. Men tend to put on weight around the midsection, whereas women tend to accumulate fat in the hips. Adults can slow both the increase in fat and decrease in muscle tone by performing more physical activity (Raguso et al., 2006). In later adulthood, weight begins to decline due to hormonal changes that reduce appetite and the signals that regulate hunger (Di Francesco et al., 2007).
Along with posture and bone health, managing sarcopenia is important in the drive for contin- ued mobility and independence. Bones, ligaments, and tendons all begin a decline in efficiency beginning in the late thirties to early forties. It is especially pronounced in athletes or others who have experienced repeated trauma such as sprained ankles and knee injuries. Speed of walking is a notable marker in two important ways. First, there is a gradual reduction in mobility, mirror- ing the changes that sarcopenia and primary aging bring on (Shumway-Cook, 2007). But walking speed also parallels an important part of lifespan changes: Although declines occur in most physi- cal areas beginning in early adulthood, for the most part they are barely noticeable until middle adulthood. That is, the typical person who is not a professional athlete does not notice a decline in skills until middle adulthood even though physical changes began long ago. (This theme applies to vision and other perceptual changes as well.) The best way to reduce the effects of sarcopenia in adulthood is resistance training—at any age. As little as two to three times a week can have a prolonged positive effect on strength and energy for tasks (Winett, Williams, & Davy, 2009).
Respiratory System The key components of the respiratory system include the lungs and the muscles that control breathing. In the same way that joints and muscles get stiffer with age, the rib cage and the effi- ciency with which membranes transfer oxygen and carbon dioxide diminishes (Jett, 2011a). Among people who do not smoke, the respiratory system remains fairly consistent with the amount of physical activity that a person usually performs. That is, muscles and respiratory stamina have a parallel decline; more lung capacity would not make a difference if muscles do not need extra oxygen. Therefore, part of the developmental process of the respiratory system is under the same kind of stresses as the rest of the body. The good news is that with regular exercise and limited exposure to cigarette smoke and other toxins, it can remain fairly efficient well into middle age.
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CHAPTER 4Section 4.3 Sexual Changes
4.3 Sexual Changes
Hormonal changes that begin to occur in early adulthood influence sensitivity to some diseases. Hormones promote sexual characteristics, like body hair and breast develop-ment, and contribute to sexual arousal and regulation of the reproductive cycle. Men and women both manufacture hormones involved in reproduction and sexuality, but they vary considerably in their level of production. Each sex experiences specific kinds of hormonal changes, which can have both a direct and indirect impact on energy, mood, cognition, and relationships.
Women For women, the major change in middle adulthood is the loss of the ability to have children. It is a gradual process that occurs over perhaps a 15-year span that is called perimenopause. In popular vernacular, this time period is often referred to as menopause. However, menopause is techni- cally a marker (a day, really) for when menstrual periods have stopped for one year. The average age of menopause is 51, but there is wide variation (Minkin & Wright, 1997). It can occur as early as 40 and as late as 60. During perimenopause, ovaries begin to produce far less of the hormones estrogen and progesterone.
Like other midlife physical changes, women generally do not notice the transition into perimeno- pause until well after its onset. During the last few years before menopause, it is normal for men- strual cycles to become intermittent, corresponding to irregular hormone production. Sometimes a month or more is skipped, other times perimenopausal women have two periods within a few weeks. Rate of flow is similarly erratic.
Symptoms of perimenopause vary greatly, with just over 50% of women reporting they did not experience the characteristic “hot flashes” that people often discuss (and associate with erratic hormone changes); in general, the majority of women do not complain of serious symp- toms (Rossi, 2004). Other women may experience fatigue, headaches, moodiness, sleep distur- bances, or other symptoms (Lyndaker & Hulton, 2004). There is also evidence that perimeno- pausal symptoms are modifiable. Women experience more severe symptoms when they smoke, drink alcohol excessively, are depressed, or use oral contraceptives (Sabia, Fournier, Mesrine, Boutron-Ruault, & Clavel-Chapelon, 2008). In addition, there are significant cultural differences. For instance, Japanese women report substantially different behavioral effects of menopause than do Western women, suggesting sociocultural factors are essential to understanding peri- menopause (Lock, 1991).
Because the culprit for many women who experience symptoms appears to be the lack of normal amounts of hormones, for many years doctors simply prescribed replacement hormones that worked to relieve symptoms. This intervention is called hormone replacement therapy (HRT).
Think and Review:
According to the text, what is the difference between the physical changes that occur during early adulthood and those that occur during middle adulthood?
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CHAPTER 4Section 4.3 Sexual Changes
However, in 1998 the Women’s Health Initiative released a study so striking that many in the medi- cal community no longer supported HRT. The study found that the combination of estrogen and progestin significantly increased a woman’s chances of a heart attack, stroke, blood clots, breast cancer, and later dementia. Even additional estrogen alone (called estrogen replacement therapy, or ERT) was related to increased chance of stroke and blood clots (NIH, 2007). A recent follow-up upheld the earlier findings (Chlebowski et al., 2013).
There are newer medical alternatives to HRT, as well as some untested homeopathic remedies. For instance, there is some evidence that relax- ation therapy and acupuncture reduce the fre- quency of hot flashes (Zaborowska et al., 2007). Like other preventive factors, regular exercise and dietary supplements (often including calcium) are essential components to a balanced treatment program. In addition, social support helps to ame- liorate emotional effects. Because of the constant flow of new information, scientists recommend that women consult with medical professionals as well as do their own research1 before deciding on any treatment protocol. Importantly, though menopause is a major milestone for women both physically and psychologically, many women wel- come this change. One survey of women over age 50 found that women associate menopause with many positive life changes, even among those who had hysterectomies (surgery to remove the uterus; Utian & Boggs, 1999).
Men Men go though less dramatic changes than women do. There is a gradual decrease of about 1% a year in the production of the hormone testosterone, starting in middle adulthood. The only substantiated impact of this change is a very gradual reduction in sex drive (Stones & Stones, 2007). Like women, sexual activity for men can remain vibrant well into old age, despite the decreasing hormone production. Testosterone replacement therapy can effectively treat some symptoms of depression, fatigue, and lower sex drive that may be associated with reduced tes- tosterone levels, but doctors do not indicate it as a general intervention. For the vast majority of men who have low testosterone and no symptoms, doctors do not recommend treatment, especially because there is a lack of long-term study of possible side effects (Bassil, Alkaade, & Morley, 2009; Bhasin et al., 2010).
Unaccompanied by other medical conditions, lower testosterone does not usually cause erectile dysfunction, which is the inability of males to achieve and maintain an erection. In a study of over 2,000 men at Johns Hopkins University, 18% said they had experienced erectile dysfunction at one time or another (Selvin, Burnett, & Platz, 2007). Just over 5% of men between 20 and 40 years of
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Social support helps women cope with hormone changes they experience during midlife.
1The National Aging Institute’s Web site (www.nia.nih.gov) is an institute of the NIH, a U.S. Federal Government agency that provides accurate, up-to-date information about aspects of aging research, information about clinical trials, educational materials and resources about aging for the general public, and information for researchers and health professionals.
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CHAPTER 4Section 4.3 Sexual Changes
age reported it, and middle-aged men reported it about 15% of the time. Not surprisingly, erectile dysfunction becomes more common as men age. Forty-four percent of men between 60 and 69 reported erectile dysfunction, which increased to 70% among men over 70 years old. A lack of exercise, obesity, and smoking were all found to have a negative effect on the ability to achieve and maintain an erection. A full 50% of men with diabetes reported this problem. Treatment for erectile dysfunction is now centered on three similar drugs—sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra)—which work by increasing blood flow to the penis. Research suggests that all are highly effective in treating the problem (McCullough, Steidle, Klee, & Tseng, 2008).
During middle age, the prostate gland, a small gland under the bladder, often becomes enlarged. As the prostate grows, it puts pressure on the urethra tube, squeezing it. Like squeezing a water hose, this results in difficulty starting to urinate, an increased urge to urinate, and a slower stream of urine. The prostate can become cancerous and can also contribute to bladder and kidney disor- ders. About 10% of men in middle age have a recognizable enlargement and may seek treatment. Medications include drugs that relax muscles around the bladder so that urinating is easier, as well as enzyme inhibitors that shrink the gland.
Whereas prostrate surgery used to be fairly routine, “active surveillance,” or waiting while receiv- ing regular medical care, is often the treatment of choice for low-risk cases of prostate cancer. Recent statistical analyses show that on average surgery only extends life 1.8 months compared to those who had regular medical follow-ups, and men who were on active surveillance enjoyed an extra 6.4 years that were free of treatment (Brower, 2012). After 20 years, 2.8% of men on active surveillance died of the disease compared to 1.6% of those who had surgery. However, the issue of quality of life is significant. Some forms of treatment affect the ability to achieve and maintain a functional erection in over 70% of men (Alemozaffar et al., 2011). Nevertheless, recent techno- logical advances and strategic marketing (especially in relation to new surgery robotics) has driven a renewed increase in surgical interventions (Cakarov, Yu, Desai, Penson & Gross, 2011).
Reproduction As we have noted, hormonal changes affect sexual drive. It is estimated that women reach their peak of sexual desire in their early thirties while men peak in their early twenties (Schmitt et al., 2002). However, peak sexual desire does not coincide with peak fertility: the capacity to repro- duce. Although in the United States there has been an upward trend in the age at which women are first becoming parents, this pattern is contrary to the natural fertility peak, which occurs in the early twenties (ESHRE Capri Workshop Group, 2005). Chances of becoming pregnant at age 40 are less than half of what they were at 20. Still, 44% of women become pregnant within of year of having regular intercourse at age 40. Importantly, a woman’s advanced age carries a significant risk of birth defects, including a high risk of chromosomal abnormalities.
In contrast to women, who experience a natural, biological limit to fertility, male reproductive functions change only gradually during adulthood. Sperm production declines by about a third up until age 60 and by half at age 80 (Whitbourne, 2002). Just as is the case with maternal age, evidence indicates that paternal age is also an important factor in health outcomes of offspring. Schizophrenia, Down syndrome, miscarriage, and other conditions are associated with paternal age, perhaps due to reduced motility (self-propelled motion) or compromised integrity in the structure of sperm (de la Rochebrochard & Thonneau, 2002; Fisch, et al., 2003; Sipos et al., 2004). Most studies evaluating the reproductive impact of older fathers on children are confounded by a number of factors, which make it difficult to attribute paternal age to outcomes. For example,
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CHAPTER 4Section 4.4 Changes in the Senses
rather than a direct deterioration of sperm, some researchers have suggested that increased infections or the accumulation of toxins in the bodies of older men may have an indirect effect on reproductive health (Sartorius & Nieschlag, 2010).
Desire In general, during early adulthood, sexual desire peaks for both men and women, and the awkwardness of adolescence gives way to more confidence and better communication. When changes do occur, the majority of middle-aged adults still engage in sex at least a few times per month. In fact, after menopause, many couples express a renewed interest in sex. Children have left the house and the potential worry about becoming pregnant has passed (Greenberg, Bruess, & Conklin, 2011). And contrary to the stereotype, adults continue to have sex well into old age (Michael, Gagnon, Laumann, & Kolata, 1994). Sexual activity continues among the elderly world- wide, including significant percentages that have intercourse multiple times per week (Nicolosi et al., 2004). In a survey among adults in the United Kingdom, over 80% of adults 50 to 90 years old reported that they remained sexually active (von Simson & Kulasegaram, 2012). Those findings are consistent with other data as well. Only about 20% of seniors surveyed worldwide agreed with the statement, “Older people no longer want sex;” the percentage was even lower in developed countries. Overall, the strongest predictor for sexual activity in old age is the availability of a part- ner and the frequency of sexual activity when younger (Mazo & Cardoso, 2011). That is, it appears that the adage “use it or lose it” has some empirical truth.
Think and Review:
From an evolutionary perspective, why would fertility rates differ between men and women?
4.4 Changes in the Senses
Although senses begin to change during middle adulthood, with the exception of vision, it is not usually immediately apparent. Changes in smell, taste, audition (hearing), and senses related to skin pressure, pain, and temperature are not often noticeable until much later. Vision The decline in visual acuity usually becomes noticeable during the early forties. Presbyopia, the loss of near vision, affects everyone before the age of 50. The lenses of the eyes—the tissue responsible for focusing images—change shape and become less elastic. Muscle flexibility that we need for focusing diminishes. Lenses become less transparent, so less light enters the eyes, result- ing in more difficulty seeing in low-light conditions (such as reading menus in darkened restau- rants). Adults in their early forties may not notice these age-related changes when in bright light conditions, but eventually everyone needs corrective lenses when reading smaller print (Strenk, Strenk, & Koretz, 2005).
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CHAPTER 4Section 4.4 Changes in the Senses
Figure 4.2: Macular degeneration
A person with macular degeneration might see the view of a street like this.
Source: .Joe McNally/Getty Images North America/ Getty Images
In addition to the normal changes of presbyopia, more than half of adults in the United States over the age of 60 will develop a cataract, or a gradual clouding of the lens of the eye (Gohdes, Balam- urugan, Larsen, & Maylahn, 2005). People with cataracts may have more difficulty viewing screen media, reading, or driving. Lights may appear to have a halo around them. Worldwide, cataracts are the leading cause of blindness, since they do not often receive treatment in the developing world (WHO, 2012). In countries with available healthcare, surgery to remove the cloudy part of the lens has become somewhat routine, and most patients report renewed eyesight and indepen- dence within a week. Nevertheless, cataracts are still the second leading cause of blindness in the United States. Although cataracts appear due to the effects of primary aging, secondary factors like smoking, diabetes, and exposure to the ultraviolet rays of the sun can fuel their progression (Mukesh et al., 2006).
The leading cause of blindness in the United States is age-related dry macular degeneration (AMD). The macula is responsible for our sharpest central vision. With AMD, the macula becomes dried out and thin, leading to deterioration in the middle of the visual field and a dramatic loss of sharp vision, right where we most need it (see Figure 4.2). Everyday events like reading and imme- diately recognizing faces or objects are particularly challenging activities. Scientists do not have a clear idea of what causes AMD, how to prevent it, or how to cure it. It is most common in those over 60 years old, and women are more likely to suffer from it than men.
Glaucoma also affects a significant proportion of the population. It occurs when increased pres- sure in the eyeball leads to permanent damage to the nerve that sends visual signals to the brain. In a way, the pressure in the eye squishes nerve impulses so that they no longer properly transmit signals. The visual field of a person with glaucoma is a reversal of those with macular degenera- tion—central vision is clear and peripheral vision is blurry. Although scientists do not completely understand its causes, damage to the eye as a result of sports injuries or other traumas increases its prevalence. If recognized early enough, doctors can usually treat glaucoma easily. They cannot restore lost vision, but they can prevent further loss. Screening takes only a moment and consists of a puff of air directed at the eye to measure pressure, in the same way that you would push on a ball to check inflation pressure. Experts recommend yearly testing for glaucoma beginning at age 40.
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CHAPTER 4Section 4.4 Changes in the Senses
Beginning in early adulthood, eyes also often develop floaters, particles from the inner lining of the eye that float around in the liquid center of the eyeball. You may notice them while looking at a white wall or at the blue sky. Floaters are sometimes annoying, but most often, they do not impair vision.
Hearing Environmental noise worsens hearing loss, especially among the generations who have been exposed to years of loud music. The ability to clearly differentiate sounds (such as listening to one voice in room full of people talking) begins to decline around age 50, likely due to changes in the way the auditory nerve transmits to the brain. In addition, the ability to hear soft sounds, such as a whisper, or higher frequency sounds, such as a birdcall, becomes more difficult. It is estimated that 30% of all people over age 65 have significant hearing loss. If you have consistently listened to very loud music, you almost certainly already have measureable hearing loss that is likely to get worse with time. While hearing aids have improved tremendously in recent years, they are still far from perfect in recreating unassisted hearing.
Taste and Smell Perceiving taste and smell relies on the ability for neural receptors in the nose, mouth, and throat to sense molecules. Chewing food activates these taste sensors, but the released aromas also travel through a network that connects the top of the throat to the nose. Therefore, the smell and taste receptors are both responsible for the perception of flavor. Although it is apparent that these senses change with age, we currently do not have a great understanding of the processes involved. Changes in taste may be due to a shrinking number of taste or odor receptors beginning in early adulthood or the reduction of saliva that would otherwise release food molecules and trigger flavor. People between 70 and 85 years of age have only about one third as many taste buds as young adults (Moller, 2003).
These chemical senses also appear to be an important physical marker for Alzheimer’s disease, a disease that impairs cognition in later adulthood. The first signs of the disease occur in various areas of the brain that process information related to smell (Murphy, Solomon, Haase, Wang, & Morgan, 2009). And abnormal behavior changes, such as reduced ability to identify specific odors, coincide with the physiological changes in the brain. Researchers also associate the capability of identifying odors with declines in memory for specific events and with cognitive impairment in general. Furthermore, among individuals with specific genetic markers for Alzheimer’s disease, impaired odor identification predicts later dementia, even when symptoms are not yet present (Calhoun-Haney & Murphy, 2005; Wilson et al., 2009).
Think and Review:
Why do you think visual changes in adulthood are more noticeable than other sensory changes?
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CHAPTER 4Section 4.5 Disease in Adulthood
4.5 Disease in Adulthood
We generally consider early adulthood as one of the healthiest periods of life. High-risk physical behavior decreases somewhat, and the prevalence of diseases like certain cancers is decades away from peaking. Throughout adulthood the pattern of diseases changes, including those that are sexually transmitted and others that are related to bone health and dementia.
Sexually Transmitted Infections and Diseases If untreated, infections that spread through sexual contact (sexually transmitted infections) even- tually turn into diseases. Over 80% of sexually transmitted diseases (STDs) occur in the under- 25 population (CDC, 2011a). However, cases of sexually transmitted infections among individuals between 50 and 90 more than doubled in the United Kingdom from 2000–2009, with similar trends evident in the United States as well (CDC, 2011c HPA, 2010). Increased use of online dat- ing sites among older adults, medications like Viagra, and more open attitudes toward sex among baby boomers are possible contributors to this trend. (See Figure 4.3 for prevalence of common STIs across the lifespan.) Bacterial infections like gonorrhea, syphilis, and the most common, chlamydia, are usually easily cured with antibiotics. However, when left untreated, they can have devastating effects. Infections in various reproductive organ parts in both men and women are common; in the long term, infertility, blindness, and death can result.
0
5
10
15
20
25
P e rc
e n
t o
f A
ll R
e p
o rt
e d
C a s e s
Gonorrhea Chlamydia
13%
1%
27%
1%
7% 9%
15%
32%
38%
3%
17%
35%
30
35
40
Age 0–14 15–19 20–24 25–29 30–39 40+
Figure 4.3: Prevalence of chlamydia and gonorrhea by age group in the United States
Adolescents and young adults represent well over half of all sexually transmitted diseases.
Source: Center for Disease Control and Prevention. (2013). STD trends in the United States: 2011 national data for
chlamydia, gonorrhea, and syphilis. Retrieved from http://www.cdc.gov/std/stats11/trends-2011.pdf
In contrast to short-term bacterial infections, viruses almost always have lifelong consequences. They include genital herpes, the human papillomavirus (HPV), which can cause genital warts and cervical cancer, and the human immunodeficiency virus (HIV), which is the virus that causes AIDS (acquired immune deficiency syndrome). AIDS is a chronic, life-threatening disease that damages the immune system, making a person less able to fight off a variety of illnesses and infections, including pneumonia. The virus is transmitted from one infected person to another by sexual con- tact (including oral sex), infected blood, sharing HIV-contaminated needles, and even from mother to child—a tremendous problem in underdeveloped countries like many of those in Africa. HIV does not spread through ordinary contact like shaking hands, hugging, or kissing.
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CHAPTER 4Section 4.5 Disease in Adulthood
Due to large cultural and international differences, demographic issues are a prominent feature of AIDS education and prevention. For example, because of increased education and awareness, AIDS/HIV has dropped from the fifth to the 20th leading cause of death in the United States. However, it remains the fourth leading cause of death among black women in the United States between the ages of 25 and 55 and is the sixth leading cause of death worldwide (CDC, 2013; WHO, 2011). In the United States, 20% of those infected with HIV are unaware that they are infected, and half of those who are aware do not receive ongoing treatment (CDC, 2011b).
Unfortunately, many people still mistakenly think of AIDS as a disease that primarily affects homo- sexual men. In fact, among the roughly 7,000 people who become infected daily throughout the world, about half (48%) are women. AIDS remains especially entrenched as the leading cause of death in sub-Saharan Africa, which is home to two thirds of the world’s HIV-infected population (Kinney et al., 2010; Griffin, 2011). In Africa, about 42% of all new infections occur among young people aged 15 to 24. An additional estimated 10% (about 3.4 million) are children under the age of 15 that will soon be ready to engage in sexual activities (UNAIDS, 2012).
Respiratory Disease Smoking, which will be covered in Chapter 5, causes holes to form in the lungs, leading to a reduction in the amount of oxygen and carbon dioxide that gets exchanged. It also destroys small airways that are used when exhaling, thereby obstructing the lungs from completely emptying and resulting in short- ness of breath. This irreversible condition is called emphysema, which is the most common form of chronic obstructive pulmonary disease (COPD). A percentage of emphysema is caused by air pollu- tion, including secondhand smoke, but about 85% of cases are due to smoking. However, only 74% of smokers and 65% of all adults have even heard of COPD (NIH, 2012).
At first, symptoms of COPD only occur upon physical exertion. But it gradually becomes harder and harder to breathe as more tissues become obstructed. Treat-
ments are available that temporarily alleviate the severity of breathing problems, but the disease remains degenerative. In later stages as less and less oxygen is carried into the blood, people with COPD can become light-headed and disoriented with just a small amount of physical exertion. Oxygen therapy may assist in some cases, but even pure oxygen cannot repair deteriorating mem- branes that simply cannot carry the oxygen into the bloodstream. In advanced stages, people with COPD eventually lose the ability to breathe altogether. Primarily because of smoking, COPD is the fourth leading cause of death worldwide, and recently moved ahead of stroke to become the third leading cause of death in the United States (NIH, 2012; WHO, 2011).
Osteoporosis
If you look at human bones under a microscope, you will see that that they are full of holes. In- stead of having a smooth texture, they look more like a honeycomb (see Figure 4.4). This means
Stockbyte/Thinkstock
The most common form of COPD is caused by smoking tobacco.
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CHAPTER 4Section 4.5 Disease in Adulthood
that bones get weaker when the “holes” in the structure become larger. Although doctors con- sider this process of osteoporosis a disease, it is also a part of maturation. Osteoporosis can be so severe that a simple movement like picking up a box or even coughing can cause a bone fracture. The loss of bone accelerates the compression of the spinal column, and individuals often develop a hunchback as the spine bends forward. Osteoporosis is the primary reason that hip fractures among the elderly occur so often.
Figure 4.4: A look at osteoporosis
Osteoporosis results in less dense, more porous bones (image on right) as compared to healthy bones (image on left).
Source: JACOPIN/BSIP/SuperStock
Beginning in early adulthood, women lose about 1% of bone mass, and men lose about .5% each year. Research is not conclusive about the relative effects of genetics and lifestyle with regard to risk factors, but we do know that certain choices can accelerate the loss of bone tissue. Smoking, lack of calcium in the diet, and heavy alcohol use are all risk factors for osteoporosis. Women are twice as likely to have osteoporosis as men. Among women it is the leading cause of broken bones (Jett, 2011b). In the United States and worldwide, there are large racial and ethnic differences in osteoporotic bone fractures, but some demographic trends have changed (Kanis et al., 2002). For instance, hip fractures among White women in the United States have declined recently, while those among minority women have increased (Brauer, Coca-Perraillon, Cutler, & Rosen, 2009; Zingmond, Melton, & Silverman, 2004).
Using Psychology to Inform Learning: Osteoporosis
Students often ask how the negative effects of low socioeconomic status (SES) can be reversed. Osteoporosis presents a clear example. On average, people who are wealthier and better edu- cated have a lower incidence of osteoporosis and its precursor, osteopenia. Lack of money and educational degrees (the chief components of SES) are associated with osteoporosis, but they do not directly cause it—rather, the behaviors we associate with a higher income and more educa- tion reduce the incidence of these diseases.
(continued)
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CHAPTER 4Section 4.5 Disease in Adulthood
Using Psychology to Inform Learning: Osteoporosis (continued)
Whenever individuals at higher risk for osteoporosis become better informed, they can engage in behaviors that mimic lower-risk individuals. Though it may be more difficult for lower-income indi- viduals who lack transportation and other resources, there is generally nothing to restrict people from exercising, not smoking, making healthier food choices, and maintaining a normal weight.
Osteoporosis receives little of the attention directed to breast cancer and other diseases, yet it has been called a “leading cause of debility and declining quality of life [for older] women world- wide” (Harris, Nealy, Jackson, & Thornton, 2012, p. 310). Beginning at a young age and continuing into old age, there are interventions that you can begin now regardless of your SES, like making sure you are consuming enough calcium and producing or consuming enough vitamin D, which the body uses to absorb calcium.
Osteoporosis carries serious risks of long-term disability and death due to complications of fractures. Each year more U.S. women experi- ence osteoporotic bone fractures than the com- bined incidence of death due to heart disease and breast cancer (Cauley, 2011). Yet, in a study of over 200,000 women aged 50 and older, nearly half were not aware that they had low bone mineral density, including 7% who were diagnosed with osteoporosis (Siris et al., 2001).
The best way to prevent osteoporosis is to invest in your bones at a young age. Bone mass does not peak until about 30 years of age, so exercising and obtaining enough calcium while tissue is still being formed is essential for opti- mal bone health. In addition, younger people in general benefit from resistance training, or weight-bearing exercises, which can include running, walking, and dancing in addition to lifting weights. Biking, swimming, and many non-weight-bearing exercise machines provide good cardiovascular conditioning, but are not particularly helpful in promoting bone health. Though for many years experts thought that weight training had a negative effect on young bodies, a compre- hensive review found that most injuries from those activities are accidental (e.g., pinching, drop- ping weights) rather than skeletal. Although once thought to be a high-risk activity for youth and younger athletes, with qualified instructors and proper supervision, it appears to be as safe as any other sports or recreational activity (Faigenbaum & Myer, 2010).
Burger/Phanie/SuperStock
Beginning in middle adulthood, women are at a higher risk of developing osteoporisis than men.
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CHAPTER 4Section 4.5 Disease in Adulthood
Skin Cancer Skin cancer is another disease that becomes more common with age. Exposure to the sun without protection and the use of tanning salons magnifies the risk for skin cancer, which is the most com- mon form of cancer overall (Doré & Chignol, 2012; Rogers et al., 2010). Milder types of skin cancer include squamous cell and basal cell. These forms often start out as reddish patches or feel like scabs that do not heal. Treatment usually takes only a few moments in a dermatologist’s office. With proper intervention, they pose little risk to long-term health.
Using Psychology to Inform Learning: Healthy Living
Imagine you need to buy a specific textbook for class and a computer on the same day. They are both available within a few miles of you, but 20 miles away in opposite directions. They are both on sale, and you only have time to go one direction. If you drive north, you can save 10% on the computer that will otherwise cost you $700. Twenty miles to the south, a used copy of the text (the only one around) is selling for $8. If you do not buy it today, it will run you $65 to purchase a new copy. Stop reading and decide which direction you will drive. Most people will choose to drive the extra distance in order to snag the deal on the text. But in this scenario, you are clearly better off saving money on the computer. The base price of the item is irrelevant; it is only impor- tant how much you are potentially saving by going the extra distance.
Similarly, in order to remain healthy, people often engage in complicated routines that provide lit- tle benefit while overlooking easy interventions. Many people drink only bottled water but think nothing of routinely baking in the sun without sunscreen. Drinking city water is usually regulated and healthy, whereas repeated sun exposure can literally be fatal. Sunscreen is inexpensive and provides an easy preventive treatment. If you are concerned about your history of sun exposure, be sure to ask your doctor or visit a dermatologist if you have specific concerns.
In the United States, about 5% of new cases of cancer each year are the most dangerous type of skin cancer, melanoma, accounting for over 12,000 yearly deaths (ACS, 2012). Melanomas may first appear to be benign moles or spots on the skin, and, as with many forms of cancer, early detection is key to its prevention. If you remember the ABCDE rule, the chance of complete recov- ery from skin cancer is excellent. See Figure 4.5 for examples of common moles and melanoma moles on the A–D spectrum.
A is for Asymmetry: A skin cancer spot is usually not symmetric.
B is for Border: A spot with unclear edges should be examined.
C is for Color: A spot with more than one color is suspicious.
D is for Diameter: A spot that is larger than a pencil eraser should be examined.
E is for Elevation: The spot is not smooth but is uneven or bumpy.
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CHAPTER 4Section 4.5 Disease in Adulthood
Figure 4.5: Common moles versus melanoma
Melanoma examples. Identify the ABCDE components.
Source: From Skin Cancer Foundation, National Cancer Institute. Retrieved from http://visualsonline.cancer.gov/
Common Moles Melanoma Moles
A
B
C
D
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CHAPTER 4Section 4.5 Disease in Adulthood
The incidence of melanoma has been increasing over the last 30 years, but the number of people who die from it has dropped, especially among those younger than 50. New diagnoses among Whites are ten times greater than among Blacks. However, late stage melanomas are significantly more common among Blacks and Hispanics than among Whites. So while melanoma is much less common among those with darker skin tones, it is much more frequently fatal. (Hu, Soza-Vento, Parker, & Kirsner, 2006). These consequences are probably due to an assumption of low risk in these groups, resulting in a lack of knowledge or pursuit of medical intervention. Importantly, if skin cancer remains localized, the chances of long-term survival (5 years and more) is 98%; if lack of detection or treatment has allowed the cancer to spread, survival rates drop to 15% (ACS, 2012).
Applying makeup that contains ultraviolet protection or a daily sunscreen with a sun protection factor (SPF) of 30 or higher is a fairly painless way to substantially reduce exposure to the harm- ful rays of the sun. Wearing a hat and sunglasses when you know you will be in the sun all day is an easy precaution as well. Water and snow reflect more rays, so people need to be extra careful around beaches, lakes, and mountains.
Diseases of the Cardiovascular System Though adults are often most afraid of cancer, more men and women die of diseases of the car- diovascular system (the heart and its arteries) than any other cause (CDC, 2013). When arteries thicken, harden, and become clogged, blood flow becomes restricted. Consequently, organs and tissues receive less oxygen and are more likely to fail. When blood and oxygen is not able to ade- quately supply the heart or brain, this results in a heart attack or stroke. Overall, vascular diseases are responsible for roughly 31% of all U.S. deaths, more than all forms of cancer combined. A person’s risk of dying from heart disease is 25 times greater in later middle age than in early adult- hood. Risks rise with added pounds, so as BMI increases, so does risk of cardiovascular disease.
Preventing stroke is strikingly similar to preventing other major diseases. Guidelines include man- aging hypertension (high blood pressure), reducing fat and salt intake, refraining from smoking, controlling diabetes, maintaining a healthy weight, exercising regularly, drinking alcohol only in moderation, and avoiding the use of illicit drugs. Perhaps the most important variable that directly affects cardio- and cerebrovascular health is the level of cholesterol that builds up in the blood. Cholesterol is a fatlike substance that is involved in a number of physiological functions, includ- ing the manufacture of cell walls. There are two types of cholesterol: “bad” cholesterol consists of low-density lipoproteins (LDL), and “good” cholesterol is made up of high-density lipoproteins (HDL). LDL (“bad” cholesterol) comes from high-fat foods like burgers, chips, and high-fat ice cream. As it travels through the bloodstream, it clings to arteries and restricts blood flow. HDL (“good” cholesterol”) is a different kind of fat. It comes from nuts, seeds, avocados, and olive, coconut, and other vegetable oils. High levels of HDL carry excess cholesterol to the liver where it is removed from the body.
Eating a diet low in hydrogenated fats and saturated fats (usually listed on food labels) and exer- cising regularly are the best ways to prevent cardiovascular diseases, though genetics plays a large role in the inheritance of cholesterol levels. Statin drugs like Lipitor are effective in lowering cholesterol, regardless of whether levels are high due to diet or genetics. The American Heart Association recommends maintaining an overall serum cholesterol number below 200, but many cardiologists recommend even lower goals. Once again, maintaining a healthy diet and avoiding sedentary activities are most effective in promoting cardiovascular health.
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CHAPTER 4Section 4.6 Degenerative Diseases of the Brain
4.6 Degenerative Diseases of the Brain
A mental health issue that occurs primarily in aging adults is dementia, a broad term that refers to an abnormal rate of deterioration in mental functioning. Neurons (brain cells) deteriorate or no longer function properly. These physical changes in the brain cause dis- turbances in memory, behavior, and ability to think clearly. Researchers believe the first signs of dementia include forgetting common directions while driving, forgetting more names than usual, or misplacing items more so than in the past. However, numerous studies have found a significant association between physical performance and dementia, even among those over 90 years old. Before cognitive declines even begin, demetia can be predicted by physical tests like grip strength (Bullain et al., 2013; Wang, Larson, Bowen, & van Belle, 2006). Others, however, believe that more studies are needed before we can make definitive conclusions (Cooper et al., 2011).
Demetia is progressive. Though not always noticeable to others in its early stages, it soon becomes problematic. During the mid- dle stages of dementia, lack of self-care and hygiene become noticeable. Memory loss becomes more dramatic, and there is diffi- culty communicating, planning, and organiz- ing. Those with moderate dementia may fre- quently become frustrated and agitated, often due to confusion about the changes they are experiencing. Throughout these stages it is important to continue to talk to the person experiencing dementia about what is happen- ing and continue to particiate in regular activi- ties—often with increased supervision. And regardless of the type of dementia, remaining physically active slows its progression (Scar- meas et al., 2011; Verdelho et al., 2012).
Cognitive exercises appear to slow dementia and specifically preserve skills. Adults who par- ticipate in activities that stimulate the brain, like reading, playing board games, doing cross-
word puzzles, and participating in discussions are less likely to experience dementia 5 years later. Other studies have found that an active mind, an active social network, and good emotional sup- port can also stave off dementia (Holtzman et al., 2004; Seidler et al., 2004) . As the population continues to age, many have suggested routine screening for dementia (including the National Health Service of the United Kingdom.) However, there is little consensus on the benefits of doing so (e.g., Brunet et al., 2013; Koekkoek, Janssen, Kappelle, Biessels, & Rutten, 2013).
Alzheimer’s Disease The most well-known and common form of dementia is Alzheimer’s disease. Its symptoms are similar to other forms of dementia. There are an estimated 5.4 million people living with Alzheim- er’s in the United States; it is the sixth leading cause of death in the United States among those
Ron Mossler
The physical signs of deterioration are evident in this photo of two men who are both 87 years old. It is apparent that one is relatively healthy and vibrant whereas the other (the author’s father) exhibits the distant, vacant look that is characteristic of dementia.
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CHAPTER 4Section 4.6 Degenerative Diseases of the Brain
65 years of age and older, and accounts for medical costs of $200 billion per year (AA, 2012; CDC, 2013). Worldwide costs for the treatment and care of Alzheimer’s and related dementia exceed $600 billion (Batsch & Mittelman, 2012).
Figure 4.6: Brain changes resulting from Alzheimer’s disease
Alzheimer’s disease causes cells to die and brain tissues to shrink. Consequently, body functions deteriorate.
Source: .2013 Alzheimer’s Association. www.alz.org. All rights reserved. Illustrations by Stacy Jannis. Reprinted with permission.
Experts do not understand the etiology of Alzheimer’s, but it is likely that it develops as a function of multiple causes. Like other forms of dementia, healthy brain tissue deteriorates, taking with it the network of knowledge and memories. There are two hallmarks that identify Alzheimer’s. Amyloid plaques are deposits that clump inside of blood vessels. These clumps may even spread, destroying more brain tissue. There are also twisted fibers, called neurofibrillary tangles, which build up inside of neurons. The tangles interfere with the ability of cells to communicate and may cause healthy neurons to die. See Figure 4.6 for a comparison of a healthy brain and one affected by advanced Alzheimer’s disease.
There is no known cure for Alzheimer’s disease, though drugs can sometimes reduce symptoms, including the behavioral changes that impact caregivers and family. Doctors most commonly prescribe medications to improve concentration and slow the progression of memory loss and confusion, but they only work for a limited time. The disease remains progressive and fatal. There is always hope among alternative treatments, but none have yet passed the standards of scientific study. As noted, the best prevention and treatment efforts include remaining mentally and physically active.
Parkinson’s Disease After Alzheimer’s, Parkinson’s disease is the second most common neurodegenerative disease and is caused by the degeneration of neurons that produce dopamine in the brain. Initial symp- toms include tremors and shaking, stiff joints, slowed movement, and problems with balance and posture. It usually progresses to difficulty in speaking and expression, diminished smiling and blinking, and cognitive deficits (Massano & Bhatia, 2012). About 30% of Parkinson’s sufferers also have dementia—roughly six times more than those without Parkinson’s. It is an incurable disease, but some symptoms can be treated. Doctors have recently begun to successfully treat advanced patients with deep brain stimulation (Williams et al., 2010). In this process, surgeons implant elec- trodes into parts of the brain that are responsible for the tremors. Electrical pulses are then sent through the electrodes in order to block the nerve impulses. Two of the best-known sufferers of Parkinson’s disease are former heavyweight-boxing champion Muhammad Ali and popular actor Michael J. Fox.
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CHAPTER 4Summary of Major Concepts
Chapter Summary
Wrapping Up and Moving Ahead Changes in physical functioning are closely connected to psychological aspects of development, including factors related to secondary aging. Beyond physical functioning, senses, visible changes, and sexuality all impact how people feel about themselves. Education about various diseases and preventive measures has a great impact on aging outcomes, often with little cost in money or time. Simple interventions like glaucoma screening and taking calcium supplements can have a tremendous effect on well-being. Other conditions are substantially impacted by lifestyle, espe- cially related to diet and exercise. The next chapter will concentrate more fully on these secondary variables and also focus on additional activities that facilitate successful aging.
Summary of Major Concepts • There are a number of theories that propose reasons why humans live as long as they do
and what causes a person’s ultimate death. • Programmed theories suggest that there are built-in limits to how long humans can live.
Genes are programmed to initiate age-related changes, which eventually lead to more susceptibility to disease.
• Damage theories view the body like mechanical devices. As the human machine ages, its component parts wear out. The current recommendations to eat foods rich in antioxi- dants grew out of damage theory.
• In addition to chronological milestones, many people look at visible changes as indica- tive of the aging process. Underneath the outward signs are corresponding changes in skin, muscle, bone, and other systems.
• Hormones govern much of our reproductive facility and sexual behavior. There are defin- itive consequences for advancing age in a woman’s ability to conceive and carry a child to term. For men, there is increasing evidence that age is a determining factor in birth outcomes as well. The vast majority of both men and women remain vital and interested in sex well into late adulthood.
• Income and education are two key factors influencing our health and development. Edu- cation has a strong relationship to income, which has a direct influence on health and availability of healthcare resources.
• About 80% of sexually transmitted infections occur in those 25 years of age and younger. However, increasing numbers of older adults are contracting STIs as preventive efforts normally focus elsewhere.
Think and Review:
What is the primary visible difference between Alzheimer’s disease and Parkinson’s disease– related dementia?
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CHAPTER 4Key Terms
• Most individuals are unaware that chronic lung diseases are one of the leading causes of death in the United States and worldwide. Smoking is by far its strongest risk factor.
• Diseases like osteoporosis and skin cancer are partly biological and partly due to life- style. The effects of these diseases can be moderated by specific interventions.
• Cardiovascular diseases kill more people in the United States and worldwide than any other cause. Lifestyle choices, including diet and exercise, and medications are impor- tant instruments in reversing its effects.
• Dementia is an especially debilitating illness that firmly blurs the boundary between physical, cognitive, and psychosocial development. Due to our aging population, its eco- nomic and social impact continues to grow.
Key Terms
acquired immune deficiency syndrome (AIDS) Refers to the symptoms of the disease that occurs due to HIV infection.
Alzheimer’s disease Most common form of progressive brain disease resulting in dementia.
amyloid plaques Deposits in the brains of Alzheimer’s patients that clump inside of blood vessels.
cataract Clouding of the lens of the eye; the leading cause of blindness worldwide.
cholesterol Fatlike substance that is manufac- tured in cells and can build up in blood due to the intake of some high-fat foods.
chronic obstructive pulmonary disease (COPD) Global term that refers to a number of lung diseases, the most common of which is emphysema.
damage theories of aging A group of theo- ries that suggest there is an accumulation of cellular or other physical damage that limits longevity.
dementia A broad term that refers to an abnormal rate of deterioration in mental func- tioning. Includes dementia related to Alzheim- er’s disease and Parkinson’s disease.
emphysema A kind of lung disease that results in shortness of breath, usually due to smoking.
erectile dysfunction Inability of males to achieve and maintain an erection.
fertility The capacity to reproduce.
free radicals Electrically charged chemicals that build up as a normal part of cell production.
glaucoma Increased pressure on the eyeball leading to damage of the optic nerve. Associ- ated with eye injury or trauma.
hormone replacement therapy (HRT) Normally, an intervention that includes estrogen and progestin to treat symptoms and outcomes related to perimenopause.
human immunodeficiency virus (HIV) The virus that causes AIDS.
human papillomavirus (HPV) A virus that can cause genital warts and cervical cancer.
hypertension High blood pressure.
life expectancy Average age of death for a specific population.
longevity Theoretical maximum number of years any one person is expected to live.
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CHAPTER 4Key Terms
macular degeneration Disease of the eye that is the leading cause of blindness in the United States.
menopause One year after the end of a woman’s last menstrual period.
mortality rate Number of deaths in a population.
neurofibrillary tangles Twisted fibers in the brains of Alzheimer’s patients, which build up inside of neurons.
osteopenia The precursor to osteoporosis; refers to lowered bone density that is not as severe as osteoporosis.
osteoporosis Disease of the bones that causes them to lose density and become more sus- ceptible to fracture.
Parkinson’s disease Second most common neurodegenerative disease that results in dementia.
perimenopause The period of hormonal changes during which women undergo a transition to cease menstruation and become unable to conceive children.
presbyopia Loss of near vision.
primary aging Aging due to biology or maturation.
programmed theories of aging A group of theories that suggest there are biological and genetic limits on how long humans can live.
prostate gland A small gland under the bladder of men; often becomes enlarged in older men.
sarcopenia Gradual loss of muscle mass and strength that begins in the thirties.
secondary aging Aging due to lifestyle or envi- ronmental circumstances.
sexually transmitted diseases Diseases that occur as a result of infections that were con- tracted through sexual contact.
statin drugs Group of drugs that are effective in lowering cholesterol in the blood.
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