global health promotion

Commentaries

The Global Burden of Mental Disorders T Bedirhan Ustiin, MD, PhD

Mental health has long been neglected in health and public health practice-much as persons with mental disorders have been segregated and seen as different, unreal, and incurable. Consequently, health professionals have trivialized the issue of mental illness. Yet, mental health disorders cause significant disability and, considered globally, exceed either HIV or cancer in terms of numbers affected. It is essential that researchers and public health professionals work together to resolve the enormous public health crisis pre- sented by mental disorders. In short, we must "mainstream" mental health.

The Magnitude ofthe Problem

In 1996, the publication of the results from the Global Burden of Disease Study' created a Cinderella effect for mental disor- ders, showing that they should indeed be dealt with seriously rather than relegated to the margin of public health concerns. This study examined the impact of 107 diseases and, rather than solely focusing on tradi- tional mortality measures, assessed disabling outcomes of diseases in a comparative framework.

Mental disorders have never been ranked in the top 10 priority lists ofpublic health sig- nificance when mortality indicators alone have been used. However, the Global Burden of Disease included "disability" in the equa- tion in calculating Disability Adjusted Life Years (DALYs), and as a result mental disor- ders ranked almost as high as cardiovascular diseases and respiratory diseases and sur- passed all different types of cancer and HIV (Figure 1). (DALYs are the sum of years of life lost because ofpremature death and years of life lived with disability; in other words, burden is determined by taking into account mortality and disability. One DALY is one lost year of healthy life. The disability com- ponent of this summary health measure is

weighted according to the severity of the dis- ability. For example, in the Global Burden of Disease Study, disability caused by major depression was found to be equivalent to that caused by blindness or paraplegia, whereas disability caused by active psy- chosis as seen in schizophrenia was esti- mated as somewhere between paraplegia and quadriplegia.) With regard to years lived with disability, depressive disorders as a sin- gle diagnostic category were the leading cause of disability worldwide. The Global Burden of Disease Study thus revealed the true magnitude of the long underestimated impact ofmental health problems.

These findings pose new challenges to policy, particularly because future projections for global DALYs in the year 2020 show a significant increase in the impact ofnoncom- municable diseases worldwide.3 Mental dis- orders are projected to increase to 15% ofthe global disease burden, and unipolar major depression could become the second leading factor in the disease burden (Table 1). In light of demographic changes and epidemiologic transitions (changes in the pattern of dis- eases),"4 as well as social factors concerning changing family structures and rising rates of urbanization, migration and mobility, and alcohol and drug use, the risks for mental dis- orders will certainly increase.

The Global Burden ofDisease Study has therefore been eye opening (and mind open- ing) for public health in terms ofmainstream- ing mental health. The study has highlighted

Requests for reprints should be sent to T. Bedirhan UJstiin, MD, PhD, Assessment Classification and Epidemiology Group, World Health Organization, 20 Avenue Appia, Geneva, Switzerland CH-1211 (e-mail: [email protected]).

Note. The views expressed in this commen- tary are those of the author and do not necessarily reflect the views of the World Health Organization.

Editor's Note. See related editorial by Neugebauer (p 1309) in this issue.

American Journal of Public Health 1315

Commentaries

the public health significance of mental disorders, providing the tool for comparative assessment in a general health context.

The Problem Is Huge- What Is the Answer?

The global burden of mental disorders highlights the magnitude of the problem as loss of life years in terms of human produc- tivity as well as social functioning.7 What can

we do to deal with this burden? Asking the question in these terms begins to guide us toward an evidence-based health policy.

Today, scientific advances bring increas- ing evidence that mental disorders are disor- ders of the brain.8 Modern brain imaging reveals that in mental disorders, neural cir- cuits responsible for thinking, mood, sleep, appetite, and behavior fail to fimction prop- erly and the regulation of critical neurotrans- mitters is impaired.9 Genetics research indi- cates that vulnerability to many mental

disorders results from the influence of multi- ple genes, acting together with environmental factors.'0 Studies of brain chemistry, of effects of psychotropic medications, and of cognitive distortions continue to inform the development of new and better treatments."1

Today we can effectively treat many mental disorders. We have come a long way in being able to diagnose and treat the major- ity of people suffering from these illnesses, and treatments for mental disorders are better studied and more efficacious than those for many other common chronic human ail- ments. The main challenge now is to bridge the gap between science and service. We should design health services so that these treatments are used effectively in the real world. One key to accomplishing this is to conceptualize mental disorders as long-term and often recurrent conditions and to design disease management strategies accordingly.'2

We need to better link efficacy (impact of treatment in clinical trials) and effective- ness (impact oftreatment in the real world) in the treatment of mental disorders. Such an effort will contribute to a powerful solution to the increasing burden of mental disorders worldwide. For example, depression is a brain disease that can be treated effectively,'3 and such treatment in turn has great impact on patients' productivity, participation in society, and quality of life. Today there are, indeed, comprehensive disease management strategies that combine the best available

September 1999, Vol. 89, No. 91316 American Journal of Public Health

Respiratory 077°h

Infections 1 7.2%

[ __ ~~~~~~~~~~~~~~~~Mental DisordersK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~9.7P/O

Substance Use Other _ \ 1.8% 37.6% H Suicide

Malignancy 1.6%5.1%h 5.8%/

Source. Based on data from The World Health Report 1999-Making a Difference. Geneva, Switzerland: World Health Organization; 1999.

FIGURE 1 -DALYs: Disability Adjusted Life Years Worldwide.

TABLE 1-Global Burden of Disease

Estimate 1990 Projection 2020

Rank Cause % Total Rank Cause % Total

1 Lower respiratory infections 8.2 1 Ischemic heart disease 5.9 2 Diarrheal diseases 7.2 2 Unipolar major depression 5.7 3 Perinatal conditions 6.7 3 Road traffic accidents 5.1 4 Unipolar major depression 3.7 4 Cerebrovascular disease 4.4 5 Ischemic heart disease 3.4 5 Chronic obstructive 4.2

pulmonary disease 6 Cerebrovascular disease 2.8 6 Lower respiratory infections 3.1 7 Tuberculosis 2.8 7 Tuberculosis 3.0 8 Measles 2.7 8 War injuries 3.0 9 Road traffic accidents 2.5 9 Diarrheal diseases 2.7 10 Congenital abnormalities 2.4 10 HIV 2.6

Source. Murray CJL, Lopez AD, eds. The Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability From Diseases, Injuries and Risk Factors in 1990 and Projected to 2020. Boston: Harvard School of Public Health, World Health Organization, World Bank; 1996.

Commentaries

practices for treating depressive disorders. With both psychosocial counseling (e.g., cog- nitive behavioral techniques or interpersonal therapy) and psychotropic medications, depressive disorders can be treated at the pri- mary care level.'4 There are even models of care (e.g., the general practice-specialist con- sultation model) developed at the health ser- vice or population level that examine the fea- sibility of more effective ways of handling various forms of disorders, depending on the setting and the patients.'5"16

The next logical step in building the efficacy-effectiveness chain is to look at cost-effectiveness. If our aim is to achieve the best "health value" for our investment, we must then promote research that will pro- duce cost-effective solutions to combat dis- ease. DALYs also provide a common frame- work for analyzing the cost-effectiveness of various interventions: how much does it cost to avert one DALY for a given condition?'7 For example, you can avert 1 DALY per $1 with vitamin A supplementation in areas where the risk of blindness from vitamin deficiency is high or 1 DALY per $4 for tuberculosis chemotherapy. On the other hand, treatment of childhood leukemia may cost as much as $1000 per DALY, and a heart transplant may cost $5000 per DALY. Currently we do not have direct cost mea- surements from empirical studies, only esti- mates for mental disease interventions-for example, depressive disorders case manage- ment may cost as much as $500 per DALY.18 We should certainly gather more evidence on the effectiveness and cost-effectiveness of mental health interventions compared with other health interventions.

Effectiveness Proven-What Next?

Once we have proven the effectiveness (and cost-effectiveness) of health interven- tions, we must prove their generalizability and sustainability within different health systems. The most effective health interven- tions must be adapted to various health sys- tems so that the interventions can be applied on a sustained basis. Tailoring health inter- ventions to fit the needs of different popula- tions and available resources of health sys- tems is another important challenge. For example, although case management of depression may be guided by universal underlying principles, it can vary in differ- ent countries, settings, and communities. One should therefore study the applicability and transportability of case management guidelines in different environments. This work will be essential to making effective

treatments more available worldwide on an equitable basis.

Once we know the factors that may influence the generalizability and sustain- ability of optimal practices in various health care systems, there is still a need for contin- uous quality management and improvement through monitoring inputs, outputs, out- comes, and costs. This is the best way to prove that investing in mental health is worthwhile. Nevertheless, all countries share a common challenge: resources are limited and their allocation entails a com- plex decision-making process that involves scientific, economic, cultural, and political factors. Hence, there are many different paths to take and decisions to make. Should we increase technical efficiency of the pro- gram in question, or try to reduce its costs? Alternatively, we may wish to change the allocation of resources, because another intervention for another health problem may yield higher benefits or lower costs. These are complex decisions that require evidence- based assessments. An important principle that should guide such decisions is that both providers and consumers should act together to reach common goals.

The cycle of evaluation outlined here may seem too complex to some who may think that an invisible hand will straighten things out-that the market economy as a wonderful social machine will take care of society's needs. However, current assess- ments show that the costs ofwrong decisions (and of not making decisions) are already enormous. Mental disorders account for at least 160 million lost years of healthy life,2 ofwhich at least 30% could have been easily averted with existing interventions.'(p495) For example, the disability weight of depressive disorder could be reduced from 0.6 to 0.3, bipolar disorder from 0.58 to 0.38, schizo- phrenia from 0.63 to 0.38. Given the possi- ble gains of these savings, investing in research to improve mental health services is certainly worthwhile.

Mainstreaming Mental Health: A Research Agenda

We also need to mainstream mental health into public health research. Mental health research should not be segregated from other types of public health research, and it should be linked with other scientific activities in public health. Recogniimng the mental health care needs ofthe society and establishing prior- ities among them will ensure that the health system as a whole is responsive to society's and individuals' needs and effective in improving mental health worldwide through research.

As a cornerstone of public health, epi- demiologic data for mental health problems will enable us to better understand mental ill- ness and assist us in allocating resources for diagnosing and managing mental disor- ders.'9 However, the data are scarce or frag- mented for many parts of the world. To address this issue, the World Health Organi- zation initiated the World Mental Health 2000 Survey, focusing on the epidemiology of mental disorders within a general health framework.20 The survey will be conducted in more than 10 countries (the United States, Spain, Germany, France, the Netherlands, Italy, South Africa, Japan, China, India, and possibly others); 5000 subjects from the gen- eral population will be interviewed in each country. Assessments will include most mental and chronic physical disorders and will focus on diagnosis and health status, disability and work loss, risk factors, health care use, and medication use.

The World Mental Health 2000 Sur- vey will use identical methodology and instruments in each country, applied with both rigorous training and quality control. This initiative will yield needed epidemio- logic parameters for many regions of the world and serve as a basis for surveillance of trends over time. Such information will give us a better picture of met and unmet needs and availability and use of services, as well as a range of risk factors (e.g., smoking, drinking, and other behaviors such as sleep, sex, and eating). It will also be useful in widening health policymakers' recognition of mental disorders as a prior- ity in public health prevention and inter- vention efforts worldwide. The fact that this survey will measure the frequency and impact ofboth mental disorders and chronic physical diseases will help us make com- parative assessments of overall disease burden and ofthe fraction that can be effec- tively averted with available or possible interventions.

In addition to descriptive epidemiologic research, we need further health services research in order to base mental health care policy on evidence. To achieve this aim, pub- lic health and mental health research should focus on the following common themes:

* Use ofhealth and social services: who, how, why, and when?

* Outcome evaluation: the impact of interventions in terms of functionality and productivity

* Health care organization: the extent of coverage of mental disorders vis-a-vis other disorders, and the means of financing the coverage (through the public sector, managed care, or private insurance?)

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Commentaries

* Consumer involvement: the extent of participation of people in services; the infor- mation gap on mental health care; knowl- edge, attitudes, and practices regarding men- tal disorders; and patients' rights

* Quality assurance: ongoing monitor- ing and surveillance and adherence to scien- tific standards, guidelines, and other norms

In the area of mental health services research, children and youth represent a sadly neglected majority. There is a major gap in our knowledge of and service provision for mental health problems among children and young people. The life-cycle transition from childhood to adulthood should be examined more carefully. Recent epidemiologic evi- dence suggests that there may be fetal pro- gramming of later-life mental illnesses.21'22 Evidence also indicates transition between certain conditions in childhood and mental disorders in adulthood. Consideration of these types of data could enable us to develop prevention programs. Likewise, recent research addressing the unity of mind and body in adults indicates that various mental disorders (e.g., depression or insomnia) pose a risk factor for developing physical prob- lems such as coronary heart disease.23

Since we have the tools to assess and intervene in mental health problems, we have a golden opportunity to use our public health research. Not only our armamentarium but also our strategic approach is important to shed light on how we can best move forward. Mental health research deals with the most complex and challenging organ of the human body and organizations ofhuman society. We now have the challenge to confront the signif- icant burden of mental disorders.

Conclusion

Mental disorders are a major part of the global burden of disease. People with mental disorders experience significant disability (i.e., limitation of functioning at the physical, personal, and societal levels)24 and poor qual- ity of life, and their families and communities are greatly affected. Furthermore, there is serious social stigma attached to mental dis- orders.

Although efficacious methods of man- aging mental disorders exist, they are not applied to a sufficient degree. This gap between reality and potential indicates a

major and unnecessary loss in the produc- tive capacity and well-being of affected per- sons and communities. Health, in this sense, refers to the productive capacity and well- being of persons and communities. We should think of investing in health as invest- ing in the future. Consequently, we cannot remain indifferent to the loss of such an important segment ofhuman and social cap- ital as is represented by those suffering from untreated mental disorders.

We must therefore research the efficacy, effectiveness, cost-effectiveness, and general- izability of mental health interventions. We need to translate the findings ofbasic science into treatment and prevention interventions. Finally, we must investigate how these inter- ventions might best be implemented in the real world. With successful medical treat- ments and guidelines, increased focus on out- comes, consumer involvement, and quality assurance, we can achieve this. But we need to strive for parity for mental disorders in our thinking and our practice. And we must mainstream mental health into research and public health. DG

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