Thesis Paper

Running Head: SMOKING AND DEPRESSION

CAUSAL RELATIONS BETWEEN SMOKING & DEPRESSION: A META ANALYSIS

Student’s Name: Mehwish Shabbir

Institution: National University

Instructor’s Name: Dr. Gina Piane

Date of Submission:

SMOKING AND DEPRESSION 2

Abstract

This paper seeks to reconcile the recent empirical and theoretical evidence on the

existence of a causal link between smoking and depressive symptoms. In order to attain this, it

sets off with comprehensive information on both depression and smoking, and the implications

of both on the public health. This is followed by a meta-analytical review of the most recent

publications on the topic, selected through searches of the leading medical and public health

databases. The choice of the studies was limited by the date of publication, the nature of the

research design and the subjects. It includes of 16 different publications, analyzed against each

other’s design, subjects, time, place and the ultimate results. These are presented individually

and in a comprehensive table, which is followed by a discussion of the findings in support and

against the existence of a causal link between smoking and the development of depressive

symptoms. While there is compelling evidence that smoking causes depression, this analysis

throws upexamins the possibility of the existence of multiple causal factors as well as common

risk factors that causes both smoking and depression. These are included in the findings

reviewed in the analysis, but are not mainstream.

SMOKING AND DEPRESSION 3

Introduction

The possibility of the existence of a causal relationship between smoking and depressive

symptoms, which may lead to the development of clinical depression presents mmay assive be a

significant public health problems risk factorfor the United States and the rest of the world.

Depression is among the four leading causes of disability in the world today, and has seen

increasing prevalence rates across the world (Kahler, Spillane, Busch, & Leventhal, 2011). It is

estimated that upwards of 121 million people across the world live with one or more forms of

depression, with more than 25% of the people lacking access to mental health care services.

Tobacco smoking on the other hand, accounts for upwards of 90% of all deaths resulting from

chronic lung diseases result from smoking (World Health Organization, 2008). If there is indeed

a causal link between smoking and depression, then the world is faced with a twin public health

threats, needing urgent attention. The comorbidity between depression and smoking arises from

when depression-prone smokers usually smoke to improve their moods. Until recently, there was

limited empirical evidence to back up these assertions, but attention has since been recast on the

issue, given the growing magnitude of the problem and the results.

SMOKING AND DEPRESSION 4

Background

Depression; a mental disorder associated with loss of interest, extreme sadness,

displeasure, poor self worth and feelings of guilt, disturbed appetite and sleep, low concentration

and energy; is a common and growing public health concern both in the developed and emerging

worlds. Depression, and the problems associated with it are recurrent and common. Depression ,

which renders it substantially hurtful toaffects the patient’s ability of the patients to live healthy

lives, and crucially, affects the productivity of the population (Center for Disease Control, 2012).

The disorder has in extreme circumstances, led to suicide, and the despite the fact that it can be

diagnosed and treated, the lack of resources and societal attitudes towards mental illnesses ensure

that the diagnoses, if any, are untimelyoften result in untimely diagnosis. In addition, even with

the correct diagnosis, there are scarce public health resources in the majority of countries across

the world, to allow for the provision of effective treatment of the patients. It would could easily

be among the highest causes of disability by the close of 2020. In the United Kingdom, it is

expected that at least one in four individuals will suffer from mental illnesses once in a year, with

depression and anxiety disorders being the highest. Across the globe, it is expected that women

face a double chance of suffering depression. and higherHigher income nations would posthave

the highest prevalence rates of depression as compared to poorer countries. In addition,The

countries that have the highest lifetime preference prevalence rates of depression at present and

would continue toand have a high burden of depression, and these include France, US and the

Netherlands (Grover, Goodwin, & Zvolensky, 2012).

While teenagers and children have always been thought to be less affected by depression,

Rrecent studies by the World Health Organization point to the increasing evidence of high rates

SMOKING AND DEPRESSION 5

of depressive symptoms among children and teens. It Depression is the main contributor of

disability among children and adolescents (McCaffery, Papandonatos, Stanton, Lloyd-

Richardson, & Niaura, 2008). Poor mental health is associated with multiple other health and

developmental problems that in turn affect educational outcomes, and lead to substance and

alcohol abuse. The prevalence rates among teenagers and children hasrates among teenagers and

children have implications on the strategies that have historically been applied to fighting the

problemdepression among adults.

There are three most common/main depressive disorder types, including dysthymia,

bipolar disorder and major depression. Major depression refers to upwards of five different

symptoms for more than two weeks, which heavily impact the ability of the patient to function

optimally, with main depressive symptoms occurring more than once in an individual’s life (U.S.

Department of Health and Human Services, 2004). Dysthymia is markedly less severe than

major depression, but it is a chronic and long-term form of depression, involving oversleeping or

insomnia, irritability, low appetite and energy as well as mild anhedonia that results in the

inability to find pleasure in multiple daily activities. The bipolar disorders/manic depression is

associated with frequent mood changes and episodes of extreme depression and happiness, with

serious consequences on the ability of an individual to function optimally. Other types of

depression exist and vary in their effects on the patient, length of disease, but are less prevalent

than dysthmia, bipolar depression and major depression.

Causes of Depression and Risk Factors

SMOKING AND DEPRESSION 6

There are multiple causal factors of depression, which have been known over centuries,

with even more emergent causes being identified along the way, with recent developments

pointing towards smoking. Known causes of depression include extreme trauma and loss, life-

long or chronic exogenous trauma, as well as lifelong endogenous depression resulting from

childhood trauma including emotional, sexual and physical abuse (Korhonen, Koivumaa-

Honkanen, Varjonen, Broms, Koskenvuo, & Kaprio, 2011). Others include inappropriate and

unclear expectations; criticisms; maternal separation; family addiction; divorce; poverty and

racism and exposure to violence. The causes of depression are structural, with traumatic

experiences serving to prevent the optimal working of the brain’s frontal lobe and the

hippocampus lobe from developing to the fullest. Neural chemical reaction, including the

existence of surplus noradrenalin due to structural multifunction of the brain and other important

bodily functions, which affect the emotional well being of an individual. There are multiple other

causes of depression; some of which are well known and established in medical and

psychological knowledge, while others are just emerging or are yet to be identified (Boden,

Fergusson, & Horwood, 2010). This paper assesses the possibility of cigarette smoking resulting

in the development of depression. subheading

The findings from this Meta analytical study are crucial, not least because of the extent of

smoking across the world, as well as potential public health implications of the combination of

smoking and depression. Up until now, cigarette smoking has been linked to coronary heart

diseases, stroke, lung cancer and chronic obstructive lung disease deaths such as emphysema and

bronchitis. Coronary heart diseases are the leading causes of death in the US, resulting directly

from the narrowing of blood vessels due to nicotine deposition, which ultimately increases blood

pressure that sets off a chain of other health problems (Center for Disease Control, 2012).

SMOKING AND DEPRESSION 7

Multiple other cancers have been associated with smoking include acute myeloid leukaemia,

cervical cancer, kidney cancer, pancreatic cancer, pharynx cancer, stomach cancer and oral

cavity cancer among others. In addition, other effects include infertility, preterm delivery, infant

mortality, stillbirths and poor birth weights. Smoking accounts for upwards of 445,000 people in

the United States alone, representing a fifth of deaths every year and representing greater

mortality than HIV/AIDS, alcohol and drug use, murders and suicides and road accidents

combined (World Health Organization, 2008). It accounts for upwards of 90% of all deaths

resulting from chronic lung diseases result from smoking.

Smoking Prevalence and Public Health Threat

It is estimated that upwards of 45.9 million adults in the United States smoke cigarettes

and use other tobacco products, with male members of the population posting a greater

prevalence (21.5%). This represents more than 19.3% of the adult population, with smoking

being the leading, preventable cause of death in the country, accounting for an estimated 443,000

deaths every year (Center for Disease Control, 2012). Individuals aged between 18 and 44 years

are the heaviest smokers, posting a prevalence rate of more than 21%, while those above the age

of 65 represent only 9.5% of the total smoking population. In addition, there are demographic

and economic factors that determine the prevalence rates of smoking. Upwards of 455 of GED

diploma, 33.4% with less than 11 years of education and 23.8 of high school diploma holders are

smokers, as compared to just under 9.9% and 6.3% of adults with undergraduate and

SMOKING AND DEPRESSION 8

postgraduate degrees. It is estimated that 28.9% of smokers live under the poverty line, with a

further 18.5% of those falling just on the line being smokers (U.S. Department of Health and

Human Services, 2004). Smoking is equally more prevalent among Alaska natives/white Indians,

non-Hispanic whites and blacks at 31.6%, 21% and 20.4% respectively, as compared to fewer

than 12.5% and 9.2% Hispanics and Asians.

It is estimated that more than 18.8 million American adults suffer from a variety of

depressive conditions including dysthymic, dipolar and bipolar disorders, representing upwards

of 9.5% of the country’s adult population. In addition, every individual is affected by depression,

either directly or through people that they know at least once through their lifetimes. There has

been a growing rate of depression among children too, with upwards of 23% of patients in every

year, while upwards of 30% the US women are depressed in any given year. The centre Center

for Disease Control and Prevention estimates that 41% of the depression patients are unable to

seek timely medication because of the social and cultural stigma, while upwards of 80% of

sufferers in the United States receive some form of pharmacological and/or therapeutic care

(Wiesbeck, Kuhl, & Wurst, 2008). The possibility of receiving medication varies according to

the demographic characteristics of the population, with 92% of black American populations that

suffer from depression, being unable to receive medication and 15% of the total depression

patients expected to commit suicide. Global statistics on depression are scarce, because of the

availability of data and information. However, it is estimated that upwards of 121 million people

across the world live with one or more forms of depression, with more than 25% of the people

lacking to health care services (World Health Organization, 2008).

SMOKING AND DEPRESSION 9

World Health Organization estimates indicate similar trends across the world, with

equally similar demographic and economic distribution of smokers across the world. In the

United Kingdom, there are more than 13.6 million smokers, with more than 34% of them being

economically or socially deprived. The smoking prevalence rates in Canada has seen a

remarkable decline from 1980, more than 28% of the population comprises of smokers, with

male smokers comprising of more than 50% of the smoking population are males. Similar trends

in education are observable, with population groups with undergraduate or postgraduate degrees

representing the lowest proportion of the smoking population (World Health Organization,

2008). Africa represents equally presents a considerable smoking problem, with far-reaching

health care difficulties. Mauritius, Seychelles, Egypt and South Africa have the highest

prevalence rates, but similar gender distribution. Individual countries in South America have the

highest smoking prevalence rates in the world, with Argentina, Chile, Bolivia, Cuba, Trinidad

and Tobacco and Uruguay posting the highest prevalence rates at 34.6%, 42%, 35.8, 44%, 37%

and 36.7% respectively (World Health Organization, 2008).

Similar trends in the distribution of across gender and other demographic groups remain

significant, with the gender differences being highly attributed to two factors. These include the

cultural predisposition of men to smoking and alcohol drinking, coupled with the

discouragement of pregnant women towards smoking. Asia and the Middle on the other hand,

has mixed prevalence rates from average to the highest levels of the smoking population, with

Jordan having a prevalence rate of more than 61% (Center for Disease Control, 2012). The

Syrian Arab Republic and Tunisia have more than 44% and 51% respectively, representing some

of the world’s highest prevalence rates.

SMOKING AND DEPRESSION 10

Organize literature review into depression and smoking, then state purpose of study linking the

two.

Methods

This paper seeks to establish the plausibility of the causal association between smoking

and depression, by asserting the existent theoretical and empirical research findings. It assesses

published, credible, academic research articles, reports and other resources. The key words and

phrases used included “Tobacco Smoking and depression”, “relationship between smoking and

depression”, “smoking and mental health”, “tobacco/cigarette smoking causes depression”,

“causes of depression’, ‘effects of tobacco smoking, depression” and “depression”. The searches

were conducted on four leading databases for medical and public health publications i.e.

Medline, Health Source: Nursing/Academic Edition, MasterFile and CINAHL. These academic

databases offer medical, nursing, veterinary medicine, preclinical sciences and a range of other

public health subjects. The searches were limited by the date of publication to between 2012 and

2005, by the inclusion of em 20070101 along with the search terms. This resulted in 3749 papers.

In order to expand the scope of the results and articles meeting these criteria, general

internet searches were carried out, especially on Google Scholar, Google Search and other search

engines. Animal studies (1242) were excluded from the subsequent analysis. In addition, the

results that duplicated initial results were also excluded. A further 2,523 studies were excluded

because they did not directly address the associated between cigarette smoking and depression.

Subsequently, an analysis of the abstract was conducted in order to determiner articles that

directly addressed the association between tobacco/cigarette smoking and depression, leading to

the selection of a total of 12 articles. In addition, the references list in every remaining eligible

SMOKING AND DEPRESSION 11

article was examined, for title relevancy. The articles with titles that were relevant to the study

matter (association between cigarette smoking and depression) were searched in the selected

databases. A further four articles were chosen to be included in the analysis. A total of 16

publications were ultimately, included in this analysis.

Table 1: Research Design

SMOKING AND DEPRESSION 12

Total # of citations identified

[Causal relationship depression & smoking –Medline & CINAHL]

4739

Relevant titles

Abstract screening 974

Irrelevant titles

(excluded after title screening)= 2,523

5437

Duplicates

69

Excluded after reading abstract

893

Animal studies

(excluded)

1242

Relevant Abstracts

(Intervention Studies)

Full text reviewed and included

12

Included on examination of references and full text reviews= 4

SMOKING AND DEPRESSION 13

Results

There is compelling evidence that tobacco smoking is related with the state and trait

aspects of susceptibility to depressive disorders, with smokers being twice as likely to experience

depression as compared to non-smokers. There occurrence of MDD accurately predicts the

possibility of taking up smoking, while taking up smoking predicts the possibility of developing

depression in the later years. The exact mechanism that links depression and smoking, but the

possibility of depression causing neuro-adaptations, which subsequently predispose them to

depression and the possibility of smoking prompting experimentation behaviours that relieve

adverse moods are plausible hypotheses, explored in Spring, et al. (2008). This study did also

explore conjoint vulnerabilities to dependence on nicotine and depression, which may increase a

person’s sensitivity to mood-enhancing impacts of nicotine. The results indicated that previously

depressed subjects had greater effects after smoking nicotinized cigarettes than de-niconized

cigarettes. Negative affective responses in response to positive mood inductions were noticeable,

indicating considerable interaction between smoking and depression vulnerability. When

depression-prone respondents smoked nicotinized cigarettes, their propensity to dispel negative

moods was increased. In addition, nicotine worsened negative affective responses to negative

mood inductions. While smoking reinforced positive moods and helped dispel negative moods, it

exacerbated the conditions in individuals who were vulnerable to depression (Spring, et al.,

2008).

The comorbidity between smoking and major depression in part stems from the fact that

individuals who are prone to depression learnt that self-administration of nicotine is helpful in

coping with pleasure deficits. The difficulty in appreciating pleasure is a known determinant of

SMOKING AND DEPRESSION 14

the occurrence of depression as well as disorder vulnerability. This condition can be assessed

objectively, and it is thought to be associated with neural systems’ dysfunction, which

subsequently affects an individual’s ability to respond to an emotional stimulus (Spring, et al.,

2008). There is a plausible linkage between self-administration of tobacco leads to a positive

mood response, but this link remains largely unexplored by mainstream research efforts that

instead focused on the ability of smoking to dispel negative moods.

Similar results were established in yet another research carried out in New Zealand,

involving a cohort of more than 1265 individuals, which revealed the existence of consistent

associations between the occurrence of depressive symptoms and nicotine dependence. In

common with Spring, et al. (2008), the resulst results were based on extensive models and

equaltionsequations, which revealed that nicotine dependence results in the increased possibility

of developing depressive symptoms. The findings from more than 1000 resondents aged

bebtween 18 and 25, smoking respondents, supported the plausible linkage between nicotine

dependence and depressive symptoms. Boden, Fergusson, & Horwood (2010) found that the

causal model that best explained the observations indicated the existence of a strong relationship

between the risk of depression and smoking behavior, with a suggestion of one more possible

causal routes. This alternative was the possible existence of common risk factors that

predisposed individuals to smoking and depression. These findings are consistent with

conclusions that have attributed cigarett smoking to the present or subsequent development of

depressive symptoms.

Ritt-Olson, et al. (2005) determined that upwards of 34% and 32% of Latina oand White

American children below the age of 14 had earlier tried on cigarettes, with the results largely

SMOKING AND DEPRESSION 15

attributeable to peer pressure among the childrenb. In addition, the researchers determined that

both environmental and genetic factors predisposed the children to smoking, and possible

development of depressive symptoms, not least because girls showed a greater tendenncy

towards developing symptoms of depression as compared to boys, with or without smoking. In

addition, considerable relationships exist between depressive symptoms and nicotine

dependence, with both smoking and depression being heaviliy determined by the environmental

(peer pressure) influences on the children. Ritt-Olson, et al. (2005) results are easily in tandem

with further results Spring, et al. (2008), which researched 18 to 65 year-old heavy smoked. The

results in this case revealed that Negative affective responses in response to positive mood

inductions were noticeable, indicating considerable interaction between smoking and depression

vulnerability. When depression-prone respondents smoked nicotinized cigarettes, their

propensity to dispel negative moods was increased. In addition, nicotine worsened negative

affective responses to negative mood inductions. While smoking reinforced positive moods and

helped dispel negative moods, it exacerbated the conditions in individuals who were vulnerable

to depression.

Hispanics living in the United States were once more targeted by other researchers, who

did however determine attribute environmental factors as predisposing the study subjects to (i)

smoking; (b) depression and (c) the perception of the effects of smoking on the individual. The

effect of acculturation and possibility of actual or perceived discrimination in causing depression

and smoking is believed to explain the linkage between smoking and depressive symptoms.

There is a heightened risk of Hispanic youths experiencing depression and smoking. The

increased risk of depression resulting from cigarette smoking resulting from acculturation of the

Hispanic youths into the mainstream US culture. The acculturation mechanism results in

SMOKING AND DEPRESSION 16

symptoms of cigarette smoking and depression, but smoking is not best understood (Richardson,

He, Curry, & Merikangas, 2012). There is a possibility that perception of depression resulted in

depressive symptoms resulting from acculturation, despite the evidence having been marginal.

Discrimination or perceptions predicted depression among both genders, while smoking was a

part of the acculturated.

The environmental influences on the smokers and the effects of smokers are explored in

multiple other research efforts seeking to understand the relationship between smoking and the

occurrence of depressive symptoms. Among these researches is Richardson, He, Curry, &

Merikangas (2012). According to the findings in this study, Anxiety disorders and depression

was markedly heightened in adolescents, who were (i) female and (ii) ever smoked as compared

against those who never did smoke with an odds ratio of 3.9 at 95% confidence level. Females

did as well show statistically considerable rates of severe anxiety and impairment, major

depressive disorder symptoms, panic disorders and other symptoms. There were slight variations

in depressive symptoms among male adolescents associated with their smoking statuses, coupled

by the fact that they were more willing to seek medical assistance.

The necessity of including the respondents’ prior smoking history in the accurate

determination of the potential risk factors that jointly predispose individuals to smoking and

depression, is addressed in Schleicher, Harris, Catley, & Nazir (2009). In this one year-long

study, depressive symptoms are clearly associated with depressive symptoms, but the link is

explained differently. The researchers assert that the expectation of positive mood gains from

smoking, which does not result after smoking, is the actual cause of depression. Cross sectional

study results indicated that depressive symptoms were good predictors of the number of

SMOKING AND DEPRESSION 17

cigarettes smoked in the past with a significance level of 0.08 (Schleicher, Harris, Catley, &

Nazir, 2009). The number of cigarettes smokes correlated to the level of depressive symptoms,

and women have markedly higher expectations on the positive effects of nicotine, and hence

more likely to be depressed than males. The amount of cigarettes smoked per day is related to the

level of depressive symptoms exhibited by the respondents, and the gender imbalances is

unknown. There is poor knowledge on the gender factors that contribute to the outcomes

observed, despite the arguments that women are generally affected by mood changes owing to

the hormonal changes that are associated with their menstrual cycles. In addition, it is thought

that men do smoke a large quantity of cigarettes in response to more variables than just

depressive symptoms and thus these factors may have a mitigating effect on the depressive

symptoms experienced by the male smokers (Schleicher, Harris, Catley, & Nazir, 2009).

The source of the negative moods havesource of the negative moods has an impact on the

effects of cigarettes smoked by an individual, and the effects on the moods of the person. Heavy

smoking reduced the negative affect resulting from abstinence in all the four different measures.

The result was much less subdued in the cases of negative mood inductions that resulted from

other sources. The results were identical for positive mood affects, with smoking reinforcements

slightly contributing to the outcome. More significantly, there results were similar for de-

nicotinized and nicotinized cigarettes. The results attained from this research point to the

existence of a link between smoking and depressive symptoms, but fail to attribute nicotine (the

active ingredient) in cigarettes to the development of depressive symptoms (Wiesbeck, Kuhl, &

Wurst, 2008). While it is not clearly stated in the research report, the findings point to the

possibility of environmental factors including peer pressure and cultural factors, which

predispose individuals to the development of depression. In addition, the possibility of the

SMOKING AND DEPRESSION 18

existence of risk factors that predispose individuals both to smoking and depression is

unexplored, and remains a possible plausible explanation in this case.

In a cross sectional study, Wiesbeck, Kuhl, & Wurst (2008) came to conclusions that

reinforced previous beliefs about the existence of a link between smoking and depression.

Considerable differences among three different smoking groups regarding the subjects with

depressive symptoms at some point in their lives. The participants who were currently smoking

posted the highest rates depressive symptoms (23.7%) and those that quit had 14.6%, while

respondents that have never smoked posted a mere 6.2%. The regression analyses revealed

cocaine and alcohol dependence, whether at present or in the past accurately predicted

depression. In addition, the relationship between depressive symptoms and smoking was

statistically significant.

Two patterns of smoking, when controlled for confounders were accurately predicted

depressive dimensions. In addition, a significant smoking and sex interaction was predicted by

the NATS dimension with an odds ratio of 1.6 at 95% significance. Inconsistent previous

smoking consistently predicted possibilities of depression, while consistent smoking had an even

greater certainty. Consistent smokers who had quit showed no heightened risk of developing

depression. When familial confounding was controlled, the relationship between persistent

smoking and subsequent development of depressive symptoms were replicated. The rest of the

results are shown in the table.

Table 2: Summary of Affirmative Studies

Reference Location, Study design Study population Results

SMOKING AND DEPRESSION 19

Time Period

Cigarette smoking and depression: tests of causal linkages using a longitudinal birth cohort Boden, J., Fergusson, D., & Horwood, J. (2010).

New Zealand,

1986-2010

Data was obtained from individuals with nicotine dependence, who exhibited symptoms of depression in the early adulthood, by use of a birth cohort. Data was collected at 4 months, 16 years, 21 and at 25 years.

n=1265

(Males= 635, Females= 630)

The population of individuals born in Christchurch (New Zealand) exhibiting nicotine dependence and depression, drawn from a cohort

There was a persistent relationship between depressive symptoms and nicotine- dependence. A structural analysis, based on equations and models indicated that the nicotine dependence heightened the risk of depressive symptoms among the respondents. In addition, smoking directly increases the risks of depression. Multiple depressive symptoms were observed among the cohort members who smoked, markedly higher than the cohort members who lacked symptoms of nicotine addiction/dependence. This was still evident after the adjustment for non-observed environmental and genetic factors, using fixed effects regressions, despite the weakened association between pooled nicotine dependence symptoms and nicotine dependence. A unidirectional association exists between nicotine dependence symptoms and depressive symptoms, with no depressive symptoms showing influence on the tendency towards nicotine dependency.

Ritt-Olson, A., Unger, J., Valente, T., Nezami, E., CP, C., Trinidad, D., et al. (2005). Exploring peers as a mediator of the association between depression and smoking in young

United States

2001

Study sought to determine the effect of peer pressure on depression and smoking. Hispanics/Latinos, Persian and Iranian populations in California. More than four school districts in urban middle class

n=1041, aged 12 to 13 years. 56% females

Data was collected from the respondents in two 45-minute classes, from a sample of students who had been randomly selected from the Board of

There is considerable with 34%, 32%, 20% and 8% Latino, White, Asian and other population groups had tried on a cigarette. Latinos had markedly higher levels than whites and Asians, with equally high levels of peer influence on smoking. Further, there is a greater tendency of female students reporting depressive symptoms than boys. There are considerable

SMOKING AND DEPRESSION 20

adolescents. Substance Use and Misuse

neighbourhoods Education records. It obtained data on depressive symptoms, peer influence and smoking, tested with regression models that included ethnicity, gender, acculturation and SES as covariates. Adjustments to the results were made, to allow for partial mediations and repeated for different covariates

association between depressive symptoms and smoking, and further, peer groups had an influence on both the outcomes.

Spring, B., Cook, J., Appelhans, B., Maloney, A., Richmond, M., Vaughn, J., et al. (2008). Nicotine effects on affective response in depression-

prone smokers.

United States

2007

Randomly selected individuals (18 to 65 years) who have smoked at least 15 cigarettes a day. Those using nicotine replacement, non- responsive to negative mood inducements or sick were excluded.

Laboratory tests were conducted after two negative and positive mood inductions at the same time. Then autobiographical memories of mood inductions were obtained through negative and positive memory questionnaires that included Likert scale ratings of their respective moods. Nicotine dependence was assessed (using Fagerström Test for Nicotine Dependence) and screening for daily smoking statuses were obtained. The data collected was then subjected to multiple statistical measures, including

Negative affective responses in response to positive mood inductions were noticeable, indicating considerable interaction between smoking and depression vulnerability. When depression-prone respondents smoked nicotinized cigarettes, their propensity to dispel negative moods was increased. In addition, nicotine worsened negative affective responses to negative mood inductions. While smoking reinforced positive moods and helped dispel negative moods, it exacerbated the conditions in individuals who were vulnerable to depression.

SMOKING AND DEPRESSION 21

Chi-Square, ANOVA and Huynh-Feldt Corrections

Schleicher, H., Harris, K., Catley, D., & Nazir, N. (2009). The role of depression and negative affect regulation expectancies in tobacco smoking among college students

United States

May 2001 and 2002

A history of depression was included and depressive symptoms were measured using the Epidemiological Studies Depression Scale (CES-D), while the expectations of positive mood gains were also gauged use of a questionnaire. Results were analyzed using SPSS v14.0, with descriptive demographic statistics summarizing different predictor variables.

N= 315

Sophomore college student smokers recruited online to complete questionnaires covering the previous 30 days.

Depressive symptoms are associated with tobacco smoking, and the expectation that smoking lowers the negative moods heavily contributes to it because it does not. Cross sectional study results indicated that depressive symptoms were good predictors of the number of cigarettes smoked in the past with a significance level of 0.08. The number of cigarettes smokes correlated to the level of depressive symptoms, and women have markedly higher expectations on the positive effects of nicotine, and hence more likely to be depressed than males.

Perkins, K., Karelitz, J., Conklin, C., Sayette, M., & Giedgowd, G. (2010). Acute negative affect relief from smoking depends on the affect situation and measure but not on nicotine.

United States

2006

Nicotine dependent smokers were assigned one in three smoking conditions at random i.e. denicotinized, no smoking or nicotine cigarettes, after completing negative mood induction procedures on every session; overnight abstinence; difficult mental tasks and negative video. The last session (fifth)

N= 104

62 males

Participants recruited by in advertisement to a community. Exclusion criteria included psychiatric patients and those who scored highly for depressive symptoms (13). The sample was 84.8% Caucasian, 1% Asian and 14.2% African American. The

The negative affect relief attained from smoking was found to be dependent the actual source of the negative affect as well as the measure of the affect. Heavy smoking reduced the negative affect resulting from abstinence in all the four different measures. The result was much less subdued in the cases of negative mood inductions that resulted from other sources. The results were identical for positive mood affects, with smoking reinforcements slightly contributing to the final outcome. More significantly, there results

SMOKING AND DEPRESSION 22

comprised of neutral mood control. Two smoking groups were allowed four puffs on assigned cigarettes, before the smoked them ad libitum throughout the mood induction sessions. The study respondents subsequently rated the level positive and negative affect on multiple measures, including cravings and withdrawals

average age was 27.2, with a daily smoking rate of 19.3+-5 for the past 9 years. The Fagerstrom Test of Nicotine Dependence was 16.

were similar for de-nicotinized and nicotinized cigarettes.

Wiesbeck, G., Kuhl, H. Y., & Wurst, F. (2008). Tobacco smoking and depression– results from the WHO/ISBRA study.

2007

United States

A cross sectional study in which respondents were interviewed using a structured questionnaire, on their smoking behaviours and depressive symptoms. The data was generated by using ISBRA/WHO study, which is an international multi- centre research that used cross-sectional design. Logistic regressive analyses were applied in predicting depressive symptoms

N= 1,849

Cross sectional members of a population

Considerable differences among three different smoking groups regarding the subjects with depressive symptoms at some point in their lives. The participants who were currently smoking posted the highest rates depressive symptoms (23.7%) and those that quit had 14.6%, while respondents that have never smoked posted a mere 6.2%. The regression analyses revealed cocaine and alcohol dependence, whether at present or in the past accurately predicted depression. In addition, the relationship between depressive symptoms and smoking was statistically significant.

Lorenzo-Blanco, E., Unger, J., Ritt- Olson, A., Soto, D., & Baezconde-

2010

United States

Surveys were administered by the trained research

N = 1124 Hispanic youth of whom 54 were female in Southern California

There is a heightened risk of Hispanic youths experiencing depression and smoking. There is also an increased risk of

SMOKING AND DEPRESSION 23

Garbanati, L. (2011). Acculturation, gender, depression, and cigarette smoking among U.S. Hispanic youth: the mediating role of perceived discrimination.

assistants in 9th to the 11th grade depression resulting from cigarette smoking resulting from acculturation of the Hispanic youths into the mainstream US culture. The acculturation mechanism results in symptoms of cigarette smoking and depression, but smoking is not best understood. There is a possibility that perception of depression resulted in depressive symptoms resulting from acculturation, despite the evidence having been marginal. Discrimination or perceptions predicted depression among both genders, while smoking was a part of the acculturated.

Korhonen, Koivumaa- Honkanen, Varjonen, Broms, Koskenvuo, & Kaprio (2011). Cigarette smoking and dimensions of depressive symptoms: longitudinal analysis among Finnish male and female twins.

Finland

1975 to 1981

Associations between depression and smoking dimensions were measured among twins in a longitudinal study assessing patterns of smoking from 1975 to 1981 using multiple categories to describing change and consistency. The Beck Depression Inventory. Pre- existing depression was assessed using the life satisfaction scale that correlated with the BDI. BDI dimensions that were measured included negative attitudes towards oneself, weight loss

4,980 male and 5,997 female Finnish twins

Two patterns of smoking, when controlled for confounders were accurately predicted depressive dimensions. In addition, a significant smoking and sex interaction was predicted by the NATS dimension with an odds ratio of 1.6 at 95% significance. Inconsistent previous smoking consistently predicted possibilities of depression, while consistent smoking had an even greater certainty. Consistent smokers who had quit showed no heightened risk of developing depression. When familial confounding was controlled, the relationship between persistent smoking and subsequent development of depressive symptoms were replicated,

SMOKING AND DEPRESSION 24

and performance impairment. Logistical and conditional regressions were applied for discordant twin couples

Cigarette smoking and mood disorders in U.S. adolescents: sex-specific associations with symptoms, diagnoses, impairment and health services use. Richardson, He, Curry, & Merikangas, (2012)

United States, 1999 to 2004

Two samples were obtained from the National Health and Nutritional Examination surveys 1999 to 2004 to determine the relationship between “never” and “ever” smoking with the possibility of developing depression represented by DSM-IV diagnoses, severe disorder, subthreshold, mental health services use, impairments and other symptoms. The data was analyzed using logistical regressive models.

N= 1884 The respondents were aged between 12 to 15 years in the first sample to determine the association of smoking to depression, while a further sample (n2) = 6336 12 to 19 years was drawn for anxiety disorders.

A sample of smokers and non-smokers on the National Health and Nutritional Examination Surveys

Anxiety disorders and depression was markedly heightened in adolescents, who were (i) female and (ii) ever smoked as compared against those who never did smoke with an odds ratio of 3.9 at 95% confidence level. Females did as well show statistically considerable rates of severe anxiety and impairment, major depressive disorder symptoms, panic disorders and other symptoms. There were slight variations in depressive symptoms among male adolescents associated with their smoking statuses, coupled by the fact that they were more willing to seek medical assistance.

McCaffery, J., Papandonatos, G., Stanton, C., Lloyd- Richardson, E., & Niaura, R. (2008). Depressive symptoms and cigarette smoking in twins from the National Longitudinal

United States, 2007

Environmental and genetic contributors to depressive symptoms co- variation and smoking were assessed among respondents from national Longitudinal Study of Adolescents Health. The

441 dyzogotic and 287 monozygotic adolescent twins

This study sought to establish a plausible relationship between environmental/genetic factors and smoking to depressive symptoms. Smoking and depressive symptoms were considerably correlated in females and males. The modelling showed that the correlation among females was attributable environmental and genetic factors that were not

SMOKING AND DEPRESSION 25

Study of Adolescent Health.

existence of depressive symptoms were measured by use of 18-item version of the Centre for Epidemiological Studies Depression Scale (CES-D). The involvement in smoking was defined by an ordinal scale on the basis of smoking frequency and recency.

commonly shared by the twins. The correlation among the males was caused by the environment that was not shared by the twins. Effectively, the environment that was not shared produced differences in the correlations between smoking and depressive symptoms, establishing credence for the belief that there exists a causal relationship between them.

Kahler, C., Spillane, N., Busch, A., & Leventhal, A. (2011). Time- varying smoking abstinence predicts lower depressive symptoms following smoking cessation treatment.

England, 2010

Clinical trials were randomized to test the effectiveness of incorporating short alcoholic interventions in smoking cessation therapies/treatment. Biochemically identified abstinence and depressive symptoms were measured in one week before, then the second, eighth, sixteenth and twenty sixth weeks following smoking cessations.

N= 236 heavy smoking and drinking subjects

The tests revealed the existence of slight increases in symptoms of depression over the time period among all the participants. There was also an inverse association between the concurrent level of depressive symptoms and the time lapsed after smoking abstinence. This pointed to the possibility that the transition following smoking cessation resulted in lower depressive symptoms. Within the prior six months after a planned attempt to quit smoking, resulted in particular weeks that were associated with lower levels of depressive symptoms.

SMOKING AND DEPRESSION 26

Research showing the lack of a Relationship

The research findings pointing to the opposite, or non conclusivenevess of the linkage

between smoking and depressive symptoms have largely taken the form of the possibility of

other factors that could have a causal effect on depression or depression and smoking. In

addition, there is a growing body of literature pointing to the causal relationship actually being

the opposite, with depression bringing on smoking behavior. Generally however,

evidence ]pointing in these directions is still comparatively difficult to come by, largely because

these research body has largely flowed from the former literatures.

Lewis, et al. (2010) asserts that while there indeed was a correlation between smoking

and depressive disorders, smoking did not cause the mood changes. The research is conducted

among pregant women, which may be limiting in the application of the findings to the rest of the

population, but the results are still revealing. The findings indicated that there is a greater

prevalence of depressive symptoms among smokers compared to the rest of the population but

there is no evidence to prove that the relationship is causal or as a resulting of multiple

confounding factors. Problems that are natural to epidemiological studies may be misleading,

and Mendelian randomizations are better in establishing the actual causal linkages between the

two variables. Levels of depression were found to correlate to the genetic predisposition of the

women as compared to smoking causing the effects, despite the existence of negative moods

among smokers. Thus the causal relationship between smoking and depressive symptoms is

over-emphasized.

Audrain-McGovern, Rodriguez, & Kassel (2009) equally demonstratesdemonstrate that

the causal relationship flowing from smoking is not entirely true, with the possibility of the cause

SMOKING AND DEPRESSION 27

relationship actually flowing from depression to smoking. The plausibility of this relationship

lies in psychological theory. Several parallel processes and a latent development curve showed a

basis for a bidirectional association between depression and teenage smoking behaviour, with

heightened depressive symptoms after the age of 14, which strongly predicted smoking patterns

and the progression through late adolescence. Higher symptoms of depression among adults who

later took on smoking, with the progression of smoking from the mid adolescence predicting a

reduction in depressive symptoms in later years. This research effectively demonstrates that the

causal relationship is from depression to smoking, and other causal factors that lead to the

development of depression are important in understanding the predisposition of individuals to

smoking (Grover, Goodwin, & Zvolensky, 2012). If indeed smoking causes, or is perceived to

cause positive mood changes for individuals who are depressed, then its abstinence should lead

to a negative turn in moods.

Table 3: Summary of studies showing the lack of a causative relationship

Reference Location,

Time Period

Study design Study population

Results

Lewis, S., Araya, R., G, S., Freathy, R., Gunnell, D., Palmer, T., et al. (2010). Smoking Is Associated with, but Does Not Cause, Depressed Mood in Pregnancy – A

United Kingdom, 1989 to 2009

Longitudinal study of children and their parents. Women were assessed for depression using the Edinburgh Postnatal Depression Scale at 8 to 32 pregnancy weeks on their

N= 14541 women participated.

Pregnant women living in Bristol with the expected delivery date of December 1992

There is a greater prevalence of depressive symptoms among smokers compared to the rest of the population but there is no evidence to prove that the relationship is causal or as a resulting of multiple confounding factors. Problems that are natural to epidemiological studies may be misleading, and Mendelian randomizations are better in establishing the actual causal linkages between the two variables. Levels of depression were found to correlate to the genetic predisposition of the women as compared to smoking causing the effects, despite the existence of negative moods among smokers. Thus the causal relationship between smoking and depressive

SMOKING AND DEPRESSION 28

Mendelian Randomization Study

lifetime and immediate symptoms of pregnancy, then smoking statuses were assessed using self-reported questionnaire. This was followed by genotyping was completed and statistical logistical regression analyses were applied to the gathered to identify the relationship between genotypes and smoking.

symptoms is over-emphasized.

Audrain- McGovern, J., Rodriguez, D., & Kassel, J. (2009). Adolescent smoking and depression: evidence for self- medication and peer smoking mediation

England, 2001 to 2008

A cohort study, in which depression, peer smoking, smoking as well as other covariates were assessed on a yearly basis from mid adolescence to the age of 18.

Adolescents from the 9th grade until the age of 14,

Several parallel processes and a latent development curve showed a basis for a bidirectional association between depression and teenage smoking behaviour, with heightened depressive symptoms after the age of 14, which strongly predicted smoking patterns and the progression through late adolescence. Higher symptoms of depression among adults who later took on smoking, with the progression of smoking from the mid adolescence predicting a reduction in depressive symptoms in later years. This research effectively demonstrates that the causal relationship is from depression to smoking.

Grover, K., Goodwin, R., & Zvolensky, M. (2012). Does current versus former smoking play a

United States, 2001 to 2002

The data was collected from the US’s National Epidemiological Survey of Alcohol &

N= 43,000. A nationally representative sample

The respondents without nicotine dependence did not show heightened mood or anxiety disorders as compared to current and dependent smokers. There was also no considerable relationship between former dependent smokers and anxiety disorders as compared to the group that had never smoked, in fact the odds of suffering from depressive symptoms

SMOKING AND DEPRESSION 29

role in the relationship between anxiety and mood disorders and nicotine dependence?

Related Conditions. The data analysis sought to determine if dependent against non- dependent smoking and former versus current smoking were associated with anxiety disorders.

were markedly reduced. The present dependent smoking was positively related to the current depressive symptoms, while former non-nicotine dependent smoking had an inverse relationship with the depressive symptoms. There is no direct causal relationship between smoking and depressive symptoms.

Parrott, A., & Murphy, R. (2012). Explaining the stress-inducing effects of nicotine to cigarette smokers.

England, 1989- 2010

In order to explain nicotine dependency’s effects on the mood of smokers in the light of studies showing that smoking results in depressive symptoms and stress, cross sectional studies were carried with the hypothesis of demonstrating that adult smokers exhibited greater depression, irritability and stress. The studies demonstrate that quitting smoking has negative mood gains and the

A cohort of smokers

N= 82, with varying levels of experience and knowledge on the effects of smoking and smoking cessation

The explanatory leaflet that was distributed helped boost the knowledge levels of the smoking cohort, which subsequently influenced the their thinking in the week that followed. This understanding subsequently boosted the thinking about smoking, and helped boost the moods of the smokers after quitting smoking, effectively proving that perceptions of negative mood gains for smoking abstinence or quitting was a socialized belief without actual scientific basis.

SMOKING AND DEPRESSION 30

adverse mood effects due to nicotine dependency stem from by deprivation reversal model. There are subtle abstinence symptoms between cigarettes smoked, which cumulatively lead to heightened levels of daily stress. Thus smoking adolescents experience greater negative mood effects and stoppage results in positive mood gains. A leaflet with these assertions was assessed among multiple smokers.

Zvolensky, M., Jenkins, E., Johnson, K., & Goodwin, R. (2011). Personality disorders and cigarette smoking among adults in the United States

United States 2009

The data was collected from the National Epidemiological Survey of Alcohol and Related Conditions

N= 43,083 The subjects who did exhibit personality disorders were dependent on nicotine, with the relationship between avoidant, dependent, histrionic, paranoid and schizoid personality problems were easily explainable using the co-occurrence of varied mood and psychological disorders. The adjustment from these clinical conditions seemed to minimize the strength of many causative relationships. The relationship between smoking and personality disorders seems to change according to different personality disorders, especially with antisocial personality disorders. Effectively multiple factors

SMOKING AND DEPRESSION 31

predict possible personality disorders and it is possible that smokers are predisposed to smoking by their pre-existing personality problems.

DISCUSSION

Antidepressant and anxiolytic effects of smoking are known to the smoking population,

despite the popular belief that smoking has a positive mood affects. The evidence established in

Boden, Fergusson, & Horwood (2010) and other literature that have linked smoking to

depression assert that the smoking population may actually be vindicated. Regardless of the

direction of the causal relationship; it is still a statistically significant relationship with important

practical implications. It is possible that the relationship could even be bidierectional, which

effectively marries the research findings from both extremes, with infrequenet or acute smoking

leading to a reduction in the negative mood affect, while chronic tobacco use exacerbates the

situation. It is also possible that both smoking and depressive symptoms are caused by similar

risk factors, and thus there really is no causal relationship between them, but their concurrence

causes a perception of a causal relationship (Munafò & Araya, 2010).

There is equally compelling evidence that genetic predisposition to smoking, with the

fibndings in the above research findings leading to conclusions to this end. The collected data is

consistent with multiple causal relationship between different fcators, which cannot be

exclusively explained by a single causal relationship. The reliance on the symptoms as against

the actual diagnoses in the mainstream literature supporting the possibility of smoking causing

depression is puzzlling, and especially because the Composiite International Diagnostic

Interview was developed as a diagnostic instrument. The authors in in Boden, Fergusson, &

SMOKING AND DEPRESSION 32

Horwood (2010); Kahler, Spillane, Busch, & Leventhal (2011) and Perkins, Karelitz, Conklin,

Sayette, & Giedgowd (2010) for instance carried out additional tests that used ordinal variables

that included diagniostic categories that resulted in similar conclusions. The symptoms of

depressions are unlike clinical depression, despite the fact that a dimensional measure of the

symptoms allows for increased power of statistical testing of the associations and negative

affectivity. Choosing the symptoms to assess smoking behavior is not usual, since the number of

cigarettes smoked a day is a good pointer to exposure.

The paradox remains in the face of mounting empirical evidence suggesting that smoking

causes depressive symptoms, while smokers insist that they get an emotional lift from smoking.

It is possible according to Munafò & Araya (2010) may be explained by the fact that nicotine has

a short half-life and the withdrawal symptoms speed in heavy smokers who have abstained for

hours. The withdrawal syndromes associated with severe abstinance from smoking helps to

better the heighten the withdrawal symptoms. The subjective experiences that have largely been

captured in successive studies are likely to be of negative affects that can be mitigated through

smoking. This assertion is supported by the fact that withdrawal symptoms are usually followed

by positive improvements in the mood.

It is however critical to point out that empirical data cannot unequivocally offer causation

evidence, not least because experimental studies are impossible due to ethical reasons (Grover,

Goodwin, & Zvolensky, 2012). The possibility of resolving the causation direction lies in the

passibility of applying Mendelian Randomization principle, in which the geneticn information

forms a central part of the tests to confirm the causal relationships/hypotheses. The [isolation of

the genetic factors that predispose individuals to depresion and/or smoking will offer the

SMOKING AND DEPRESSION 33

solution or narrow down the search. In addition, it will allow for the easier identification of the

environemental factors that lead tpo the same result, which should ultimately facilitate the

establihment of the true causal link between the two variables. Genetics has alaredy been

exploredf in Lewis, et al. (2010), which resulted in inconclusive evidence on the genetic

predisposition and the role of enviornmental factors to causing both smoking and depression.

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