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Chapter 2: Burden of Mental and Behavioural Disorders: Previous page | 1,2,3,4,5,6,7,8

Determinants of mental and behavioural disorders

  Chapter 2

A variety of factors determine the prevalence, onset and course of mental and behavioural disorders. These include social and economic factors, demographic factors such as sex and age, serious threats such as conflicts and disasters, the presence of major physical diseases, and the family environment, which are briefly described here to illustrate their impact on mental health.


Poverty and associated conditions of unemployment, low educational level, deprivation and homelessness are not only widespread in poor countries, but also affect a sizeable minority of rich countries. Data from cross-national surveys in Brazil, Chile, India and Zimbabwe show that common mental disorders are about twice as frequent among the poor as among the rich (Patel et al. 1999). In the United States, children from the poorest families were found to be at increased risk of disorders in the ratio of 2:1 for behavioural disorders and 3:1 for comorbid conditions (Costello et al. 1996). A review of 15 studies found the median ratio for overall prevalence of mental disorders between the lowest and the highest socioeconomic categories was 2.1:1 for one year and 1.4:1 for lifetime prevalence (Kohn et al. 1998). Similar results have been reported from recent studies carried out in North America, Latin America and Europe (WHO International Consortium of Psychiatric Epidemiology 2000). Figure 2.6 shows that depression is more common among the poor than the rich.

Figure 2.6 Prevalence of depression in low versus high income groups, selected countries

There is also evidence that the course of disorders is determined by the socioeconomic status of the individual (Kessler et al. 1994; Saraceno & Barbui 1997). This may be a result of service-related variables, including barriers to accessing care. Poor countries have few resources for mental health care and these resources are often unavailable to the poorer segments of society. Even in rich countries, poverty and associated factors such as lack of insurance coverage, lower levels of education, unemployment, and racial, ethnic and language minority status create insurmountable barriers to care. The treatment gap for most mental disorders is large, but for the poor population it is massive. In addition, poor people often raise mental health concerns when seeking treatment for physical problems, as shown in Box 2.4.

Box 2.4 Poor people's views on sickness of body and mind

When questioned about their health,1 poor people mention a broad range of injuries and illnesses: broken limbs, burns, poisoning from chemicals and pollution, diabetes, pneumonia, bronchitis, tuberculosis, HIV/AIDS, asthma, diarrhoea, typhoid, malaria, parasitic diseases from contaminated water, skin infections, and other debilitating diseases. Mental health problems are often raised jointly with physical concerns, and hardships associated with drug and alcohol abuse are also frequently discussed. Stress, anxiety, depression, lack of self-esteem and suicide are among the effects of poverty and ill-health commonly identified by discussion groups. A recurring theme is the stress of not being able to provide for one's family. People associate many forms of sickness with stress, anguish and being ill at ease, but often pick out three for special mention: HIV/AIDS, alcoholism and drugs.

HIV/AIDS has a marked impact: in Zambia a youth group made a causal link between poverty and prostitution, AIDS and, finally, death. Group discussions in Argentina, Ghana, Jamaica, Thailand, Viet Nam, and several other countries also mention HIV/AIDS and related diseases as problems that affect their livelihoods and strain the extended family.

People regard drug use and alcoholism as causes of violence, insecurity and theft, and see money spent on alcohol or other drugs, male drunkenness, and domestic violence as syndromes of poverty. Many discussion groups from all regions report problems of physical abuse of women when husbands come home drunk, and several groups find that beer-drinking leads to promiscuity and disease. Alcoholism is especially prevalent among men. In both urban and rural Africa, poor people mention it more frequently than drugs.

Drug abuse is mentioned frequently in urban areas, especially in Latin America, Thailand and Viet Nam. It is also raised in parts of Bulgaria, Kyrgyzstan, the Russian Federation and Uzbekistan. People addicted to drugs are miserable, and so are their families.

1Narayan D et al. (2000). Voices of the poor, crying out for change. New York, Oxford University Press for the World Bank.

The relationship between mental and behavioural disorders, including those related to alcohol use, and the economic development of communities and countries has not been explored in a systematic way. It appears, however, that the vicious cycle of poverty and mental disorders at the family level (see Figure 1.4) may well be operative at the community and country levels.


There has been an increasing focus on sex differences in studying the prevalence, causation and course of mental and behavioural disorders. A higher proportion of women among the inmates of asylums and other treatment facilities was noted in earlier centuries, but it is not clear whether mental disorders were indeed more prevalent among women or whether women were brought in more frequently for treatment.

Recent community studies using sound methodology have revealed some interesting differences. The overall prevalence of mental and behavioural disorders does not seem to be different between men and women. Anxiety and depressive disorders are, however, more common among women, while substance use disorders and antisocial personality disorders are more common among men (Gold 1998). Almost all studies show a higher prevalence of depressive and anxiety disorders among women, the usual ratio being between 1.5:1 and 2:1. These findings have been seen not only in developed but also in a number of developing countries (Patel et al. 1999; Pearson 1995). It is interesting to note that sex differences in rates of depression are strongly age-related; the greatest differences occur in adult life, with no reported differences in childhood and few in the elderly.

Many reasons for the higher prevalence of depressive and anxiety disorders among women have been proposed. Genetic and biological factors certainly play some role, as indicated in particular by the close temporal relationship between higher prevalence and reproductive age range with associated hormonal changes. Mood swings related to hormonal changes as part of the menstrual cycle and following childbirth are well documented. Indeed, depression within a few months of childbirth can be the beginning of a recurrent depressive disorder. Psychological and social factors are, however, also significant for the gender difference in depressive and anxiety disorders. There may be more actual as well as perceived stressors among women. The traditional role of women in societies exposes women to greater stresses as well as making them less able to change their stressful environment.

Another reason for the sex differences in common mental disorders is the high rate of domestic and sexual violence to which women are exposed. Domestic violence is found in all regions of the world and women bear the major brunt of it (WHO 2000b). A review of studies (WHO 1997a) found the lifetime prevalence of domestic violence to be between 16% and 50%. Sexual violence is also common; it has been estimated that one in five women suffer rape or attempted rape in their lifetime. These traumatic events have their psychological consequences, depressive and anxiety disorders being the most common. A recent study in Nicaragua found that women with emotional distress were six times more likely to report spousal abuse compared with women without such distress (Ellsberg et al. 1999). Also, women who had experienced severe abuse during the past year were 10 times more likely to experience emotional distress than women who had never experienced abuse.

The WHO Multi-country Study on Women's Health and Domestic Violence and the World Studies of Abuse in Family Environments (WorldSAFE) by the International Network of Clinical Epidemiologists (INCLEN 2001) are studying the prevalence and health consequences for women of intimate partner violence in population-based samples in different settings. In both studies, women are asked if they have contemplated or attempted suicide. Preliminary results indicate a highly significant relationship between such violence and contemplation of suicide (see Table 2.3). Moreover, the same significant patterns were found for sexual violence alone and in combination with physical violence.

Table 2.3 Relationship between domestic violence and contemplation of suicide

% of women who have ever thought of committing suicide (P<0.001)
Experience of physical violence Brazil1 Chile2 Egypt2 India2 Indonesia3 Philippines2 Peru1 Thailand1
  (n=940) (n=422) (n=631) (n=6327) (n=765) (n=1001) (n=1088) (n=2073)
Never 21 11 7 15 1 8 17 18
Ever 48 36 61 64 11 28 40 41
1WHO Multi-country Study on Women's Health and Domestic Violence (preliminary results, 2001). Geneva, World Health Organization (unpublished document).
2International Network of Clinical Epidemiologists (INCLEN) (2001). World Studies of Abuse in Family Environments (WorldSAFE). Manila, International Network of Clinical Epidemiologists. This survey questioned women about "severe physical violence".
3Hakimi M et al. (2001). Silence for the sake of harmony: domestic violence and women's health in Central Java. Yogyakarta, Indonesia, Program for Appropriate Technology in Health.

In contrast to depressive and anxiety disorders, severe mental disorders such as schizophrenia and bipolar affective disorder do not show any clear differences of incidence or prevalence (Kessler et al. 1994). Schizophrenia, however, seems to have an earlier onset and a more disabling course among men (Sartorius et al. 1986). Almost all the studies show that substance use disorders and antisocial personality disorders are much more common among men than among women.

Comorbidity is more common among women than men. Most often, it takes the form of a co-occurrence of depressive, anxiety and somatoform disorders, the latter being the presence of physical symptoms that are not accounted for by physical diseases. There is evidence that women report a higher number of physical and psychological symptoms than men.

There is also evidence that the prescription of psychotropic medicines is higher among women (see Figure 1.5); these drugs include anti-anxiety, antidepressant, sedative, hypnotic and antipsychotic drugs. This higher use of drugs may be partly explained by the higher prevalence of common mental disorders and a higher rate of help-seeking behaviour. A significant factor is likely to be the prescribing behaviour of physicians, who may take the easier path of prescription when faced with a complex psychosocial situation that actually requires psychological intervention.

The higher prevalence of substance use disorders and antisocial personality disorder among men is a consistent finding across the world. In many regions of the world, however, substance use disorders are increasing rapidly among women.

Women also bear the brunt of care for the mentally ill within the family. This is becoming increasingly crucial, as more and more individuals with chronic mental disorders are being looked after in the community.

To summarize, mental disorders have clear sex determinants that need to be better understood and researched in the context of assessing the overall burden.


Age is an important determinant of mental disorders. Mental disorders during childhood and adolescence have been briefly described above. A high prevalence of disorders is also seen in old age. Besides Alzheimer's disease, discussed above, elderly people also suffer from a number of other mental and behavioural disorders. Overall, the prevalence of some disorders tends to rise with age. Predominant among these is depression. Depressive disorder is common among elderly people: studies show that 8­20% being cared for in the community and 37% being cared for at the primary level are suffering from depression. A recent study on a community sample of people over 65 years of age found depression among 11.2% of this population (Newman et al. 1998). Another recent study, however, found the point prevalence of depressive disorders to be 4.4% for women and 2.7% for men, although the corresponding figures for lifetime prevalence were 20.4% and 9.6%. Depression is more common among older people with physically disabling disorders (Katona & Livingston 2000). The presence of depression further increases the disability among this population. Depressive disorders among elderly people go undetected even more often than among younger adults because they are often mistakenly considered a part of the ageing process.

Conflicts and disasters

Conflicts, including wars and civil strife, and disasters affect a large number of people and result in mental problems. It is estimated that globally about 50 million people are refugees or are internally displaced. In addition, millions are affected by natural disasters including earthquakes, floods, typhoons, hurricanes and similar large-scale calamities (IFRC 2000). Such situations take a heavy toll on the mental health of the people involved, most of whom live in developing countries, where capacity to take care of these problems is extremely limited. Between a third and half of all the affected persons suffer from mental distress. The most frequent diagnosis made is post-traumatic stress disorder (PTSD), often along with depressive or anxiety disorders. In addition, most individuals report psychological symptoms that do not amount to disorders. PTSD arises after a stressful event of an exceptionally threatening or catastrophic nature and is characterized by intrusive memories, avoidance of circumstances associated with the stressor, sleep disturbances, irritability and anger, lack of concentration and excessive vigilance. The point prevalence of PTSD in the general population, according to GBD 2000, is 0.37%. The specific diagnosis of PTSD has been questioned as being culture-specific and also as being made too often. Indeed, PTSD has been called a diagnostic category that has been invented based on sociopolitical needs (Summerfield 2001). Even if the suitability of this specific diagnosis is uncertain, the overall significance of mental morbidity among individuals exposed to severe trauma is generally accepted.

Studies on victims of natural disasters have also shown a high rate of mental disorders. A recent study from China found a high rate of psychological symptoms and a poor quality of life among earthquake survivors. The study also showed that post-disaster support was effective in the improvement of well-being (Wang et al. 2000).

Major physical diseases

The presence of major physical diseases affects the mental health of individuals as well as of entire families. Most of the seriously disabling or life-threatening diseases, including cancers in both men and women, have this impact. The case of HIV/AIDS is described here as an illustration of this effect.

HIV is spreading very rapidly in many parts of the world. At the end of 2000, a total of 36.1 million people were living with HIV/AIDS and 21.8 million had already died (UNAIDS 2000). Of the 5.3 million new infections in 2000, 1 in 10 occurred in children and almost half among women. In 16 countries of sub-Saharan Africa more than 10% of the population of reproductive age is now infected with HIV. The HIV/AIDS epidemics has lowered economic growth and is reducing life expectancy by up to 50% in the hardest hit countries. In many countries HIV/AIDS is now considered a threat to national security. With neither cure nor vaccine, prevention of transmission remains the principal response, with care and support for those infected with HIV offering a critical entry point.

The mental health consequences of this epidemic are substantial. A proportion of individuals suffer psychological consequences (disorders as well as problems) as a result of their infection. The effects of intense stigma and discrimination against people with HIV/AIDS also play a major role in psychological stress. Disorders range from anxiety or depressive disorders to adjustment disorder (Maj et al. 1994a). Cognitive deficits are also detected if looked for specifically (Maj et al. 1994b; Starace et al. 1998). In addition, family members also suffer the consequences of stigma and, later, of the premature deaths of their infected family members. The psychological effects on members of families broken and on children orphaned by AIDS have not been studied in any detail, but are likely to be substantial.

These complex situations, where a physical condition leads to psychosocial consequences at individual, family and community levels, require comprehensive assessment in order to determine their full impact on mental health. There is a need for further research in this area.

Family and environmental factors

Mental disorders are firmly rooted in the social environment of the individual. A variety of social factors influence the onset, course and outcome of these disorders.

People go through a series of significant events in life ­ minor as well as major. These may be desirable (such as a promotion at work) or undesirable (for example, bereavement or business failure). It has been observed that there is an accumulation of life events immediately before onset of mental disorders (Brown et al. 1972; Leff et al. 1987). Though undesirable events predominate before onset or relapse in depressive disorders, a higher occurrence of all events (undesirable and desirable) precedes other mental disorders. Studies suggest that all significant events in life act as stressors and, coming in quick succession, predispose the individual to mental disorders. This effect is not limited to mental disorders and has also been demonstrated to be associated with a number of physical diseases, for example myocardial infarction.

Of course, life events are only one of several interacting factors (such as genetic predisposition, personality, and coping skills) in the causation of disorders.

The relevance of life events research lies mainly in identifying individuals who are at a higher risk because of experiencing major life events in quick succession (for example, loss of job, loss of spouse, and change of residence). Initially this effect was observed for depression and schizophrenia, but subsequently an association has been found between life events and a variety of other mental and behavioural disorders and conditions. Notable among these is suicide.

The social and emotional environment within the family also plays a role in mental disorders. Although attempts to link serious mental disorders such as schizophrenia and depression to the family environment have been made for a long time (Kuipers & Bebbington 1990), some definitive advances have been made in the recent past. The social and emotional environment within the family has clearly been correlated with relapses in schizophrenia but not necessarily with the onset of the disorder. The initial observation was that patients with schizophrenia who went back to stay with parents after a period of hospitalization relapsed more frequently. This led to some research on the cause of this phenomenon. Most studies have used the concept of "expressed emotions" of family members towards the individual with schizophrenia. Expressed emotions in these studies have included critical comments, hostility, emotional over-involvement and warmth.

A large number of studies from all regions of the world have demonstrated that expressed emotionality can predict the course of schizophrenia, including relapses (Butzlaff & Hooley 1998). There is also evidence that changing the emotional environmental within families can have an additive effect on prevention of relapses by antipsychotic drugs. These findings are useful for improving the care of selected patients within their family environment and also recall the importance of social factors in the course and treatment of serious mental disorders such as schizophrenia.

Chapter 2: Burden of Mental and Behavioural Disorders: 1,2,3,4,5,6,7,8

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