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Chapter 1: A public health approach to mental health :
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1,2,3,4
Understanding mental and behavioural disorders
While the promotion of positive mental health in all members of society is clearly an important goal, much remains to be learned about how to achieve this objective. Conversely, effective interventions exist today for a range of mental health problems. Because of the large number of people affected by mental and behavioural disorders, many of whom never receive treatment, and the burden that results from untreated disorders, this report focuses upon mental and behavioural disorders rather than the broader concept of mental health.
Mental and behavioural disorders are a set of disorders as defined by the International statistical classification of diseases and related health problems (ICD-10). While symptoms vary substantially, these disorders are generally characterized by some combination of abnormal thoughts, emotions, behaviour and relationships with others. Examples include schizophrenia, depression, mental retardation, and disorders due to psychoactive substance use. A more detailed consideration of mental and behavioural disorders appears in Chapters 2 and 3. The continuum from normal mood fluctuations to mental and behavioural disorders is illustrated in Figure 1.3 for the case of depressive symptoms.
Figure 1.3 The continuum of depressive symptoms in the population
The artificial separation of biological from psychological and social factors has been a formidable obstacle to a true understanding of mental and behavioural disorders. In reality, these disorders are similar to many physical illnesses in that they are the result of a complex interaction of all these factors.
For years, scientists have argued over the relative importance of genetics versus environment in the development of mental and behavioural disorders. Modern scientific evidence indicates that mental and behavioural disorders are the result of genetics plus environment or, in other words, the interaction of biology with psychological and social factors. The brain does not simply reflect the deterministic unfolding of complex genetic programmes, nor is human behaviour the mere result of environmental determinism. Prenatally and throughout life, genes and environment are involved in a set of inextricable interactions. These interactions are crucial to the development and course of mental and behavioural disorders.
Modern science is showing, for example, that exposure to stressors during early development is associated with persistent brain hyper-reactivity and increased likelihood of depression later in life (Heim et al. 2000). Promisingly, behaviour therapy for obsessivecompulsive disorder has been shown to result in changes in brain function that are observable through imaging techniques and equal to those that can be achieved by using drug therapy (Baxter et al. 1992). Nonetheless, the discovery of genes associated with increased risk of disorders will continue to provide critically important tools which, together with improved understanding of neural circuits, will yield important new insights into the development of mental and behavioural disorders. There is still much to be learned about the specific causes of mental and behavioural disorders, but contributions from neuroscience, genetics, psychology and sociology, among others, have played an important role in informing our understanding of these complex relationships. A science-based appreciation of the interactions between the various factors will contribute mightily to eradicating ignorance and putting a stop to the maltreatment of people with these problems.
Biological factors
Age and sex are associated with mental and behavioural disorders, and these associations are discussed in Chapter 2.
Mental and behavioural disorders have been shown to be associated with disruptions of neural communication within specific circuits. In schizophrenia, abnormalities in the maturation of neural circuits may produce detectable changes in pathology at the cellular and gross tissue level that result in inappropriate or maladaptive information processing (Lewis & Lieberman 2000). In depression, however, it is possible that distinct anatomical abnormalities may not occur; rather, risk of illness may be due to variations in the responsiveness of neural circuits (Berke & Hyman 2000). These, in turn, may reflect subtle variations in the structure, location, or expression levels of proteins critical to normal function. Some mental disorders, such as psychoactive substance dependence, may be viewed in part as the result of maladaptive synaptic plasticity. In other words, drug-driven or experience-driven alterations in synaptic connections can produce long-term alterations in thinking, emotion and behaviour.
In parallel with progress in neuroscience has come progress in genetics. Almost all of the common severe mental and behavioural disorders are associated with a significant genetic component of risk. Studies of the mode of transmission of mental disorders within extended multigenerational families, and studies comparing risk of mental disorders in monozygotic (identical) versus dizygotic (fraternal) twins have, however, led to the conclusion that risk of the common forms of mental disorders is genetically complex. Mental and behavioural disorders are predominantly due to the interaction of multiple risk genes with environmental factors. Further, a genetic predisposition to develop a particular mental or behavioural disorder may manifest only in people who also experience specific environmental stressors that elicit the pathology. Examples of environmental factors could range from exposure to psychoactive substances as a fetus, to malnutrition, infections, disrupted family environments, neglect, isolation and trauma.
Psychological factors
Individual psychological factors are also related to the development of mental and behavioural disorders. One main finding throughout the 20th century that has shaped current understanding is the crucial importance of relationships with parents or other caregivers during childhood. Affectionate, attentive and stable caring allows infants and young children to develop normally such functions as language, intellect and emotional regulation. Failure may be due to the mental health problems, illness or death of a caregiver. The child may be separated from the caregiver because of poverty, war or population displacement. The child may lack care because of the unavailability of social services in the broader community. Regardless of the specific cause, when children are deprived of nurture from their caregivers they are more likely to develop mental and behavioural disorders, either during childhood or later in life. Evidence for this finding comes from infants living in institutions that did not provide sufficient social stimulation. Although these children received adequate nutrition and bodily care, they were likely to show serious impairments in interactions with others, in emotional expressiveness, and in coping adaptively to stressful life events. In some cases, intellectual deficits also occurred.
Another key finding is that human behaviour is partly shaped through interactions with the natural or social environment. This interaction can result in either desirable or undesirable consequences for the individual. Basically, individuals are more likely to engage in behaviours that are "rewarded" by the environment, and less likely to engage in behaviours that are ignored or punished. Mental and behavioural disorders can thus be viewed as maladaptive behaviour that has been learned either directly or through observing others over time. Evidence for this theory comes from decades of research on learning and behaviour, and is further substantiated by the success of behaviour therapy, which uses these principles to help people change maladaptive patterns of thinking and behaving.
Finally, psychological science has shown that certain types of mental and behavioural disorders, such as anxiety and depression, can occur as the result of failing to cope adaptively to a stressful life event. Generally, people who try to avoid thinking about or dealing with stressors are more likely to develop anxiety or depression, whereas those who share their problems with others and attempt to find ways of managing stressors function better over time. This finding has prompted the development of interventions that consist of teaching coping skills.
Collectively, these discoveries have contributed to our understanding of mental and behavioural disorders. They have also been the basis for the development of a range of effective interventions, which are discussed in greater detail in Chapter 3.
Social factors
Although social factors such as urbanization, poverty and technological change have been associated with the development of mental and behavioural disorders, there is no reason to assume that the mental health consequences of social change are the same for all segments of a given society. Changes usually exert differential effects based on economic status, sex, race and ethnicity.
Between 1950 and 2000, the proportion of urban populations in Asia, Africa, and Central and South America increased from 16% to fully one half of the populations of these regions (Harpham & Blue 1995). In 1950, the populations of Mexico City and São Paulo were 3.1 million and 2.8 million, respectively, but by 2000 the estimated population of each was 10 million. The nature of modern urbanization may have deleterious consequences for mental health through the influence of increased stressors and adverse life events, such as overcrowded and polluted environments, poverty and dependence on a cash economy, high levels of violence, and reduced social support (Desjarlais et al. 1995). Approximately half of the urban populations in low and middle income countries live in poverty, and tens of millions of adults and children are homeless. In some areas, economic development is forcing increasing numbers of indigenous peoples to migrate to urban areas in search of a viable livelihood. Usually, migration does not bring improved social well-being; rather, it often results in high rates of unemployment and squalid living conditions, exposing migrants to social stress and increased risk of mental disorders because of the absence of supportive social networks. Conflicts, wars and civil strife are thus associated with higher rates of mental health problems, and these are discussed in Chapter 2.
Rural life is also fraught with problems for many people. Isolation, lack of transport and communications, and limited educational and economic opportunities are common difficulties. Moreover, mental health services tend to concentrate clinical resources and expertise in larger metropolitan areas, leaving limited options for rural inhabitants in need of mental health care. A recent study of suicide in the elderly in some urban and rural areas of Hunan province, China, showed a higher suicide rate in rural areas (88.3 per 100 000) than in urban areas (24.4 per 100 000) (Xu et al. 2000). Elsewhere, rates of depression among rural women have been reported to be more than twice those of general population estimates for women (Hauenstein & Boyd 1994).
The relationship between poverty and mental health is complex and multidimensional (Figure 1.4). In its strictest definition, poverty refers to a lack of money or material possessions. In broader terms, and perhaps more appropriately for discussions related to mental and behavioural disorders, poverty can be understood as the state of having insufficient means, which may include the lack of social or educational resources. Poverty and associated conditions such as unemployment, low education, deprivation and homelessness, are not only widespread in poor countries, but also affect a sizeable minority of rich countries. The poor and the deprived have a higher prevalence of mental and behavioural disorders, including substance use disorders. This higher prevalence may be explainable both by higher causation of disorders among the poor and by the drift of the mentally ill into poverty. Though there has been controversy about which of these two mechanisms accounts for the higher prevalence among the poor, the available evidence suggests that both are relevant (Patel 2001). For example, the causal mechanism may be more valid for anxiety and depressive disorders, while the drift theory may account more for the higher prevalence of psychotic and substance use disorders among the poor. But the two are not mutually exclusive: individuals may be predisposed to mental disorder because of their social situation and those who develop disorders may face further deprivation as a result of being ill. Such deprivation includes lower levels of educational attainment, unemployment and, in extreme cases, homelessness. Mental disorders may cause severe and sustained disabilities, including an inability to work. If sufficient social support is not available, which is often the case in developing countries without organized social welfare agencies, impoverishment is quick to develop.
Figure 1.4 The vicious cycle of poverty and mental disorders
There is also evidence that the course of mental and behavioural disorders is determined by the socioeconomic status of the individual. This may be the result of an overall lack of mental health services together with the barriers faced by certain socioeconomic groups in accessing care. Poor countries have very few resources for mental health care and these are often unavailable to the poorer segments of society. Even in rich countries, poverty along with associated factors such as lack of insurance coverage, lower educational level, unemployment and minority status in terms of race, ethnicity and language can create insurmountable barriers to care. The treatment gap for most mental disorders is high, but in the poor population it is indeed massive.
Across socioeconomic levels, the multiple roles that women fulfil in society put them at greater risk of experiencing mental and behavioural disorders than others in the community. Women continue to bear the burden of responsibility associated with being wives, mothers, educators and carers of others, while they are increasingly becoming an essential part of the labour force and in one-quarter to one-third of households they are the prime source of income. In addition to the pressures placed on women because of their expanding and often conflicting roles, they face significant sex discrimination and associated poverty, hunger, malnutrition, overwork and domestic and sexual violence. Not surprisingly, therefore, women have been shown to be more likely than men to be prescribed psychotropic drugs (see Figure 1.5). Violence against women constitutes a major social and public health problem, affecting women of all ages, cultural backgrounds, and income levels.
Figure 1.5 Average female/male ratio of psychotropic drug use, selected countries
Racism, too raises important issues. Although there is still reluctance in some quarters to discuss racial and ethnic bigotry in the context of mental health concerns, psychological, sociological and anthropological research has shown racism to be related to the perpetuation of mental problems. The available evidence indicates that people long targeted by racism are at heightened risk for developing mental problems or experiencing a worsening of existing ones. And people who practise and perpetuate racism themselves are found to have or to develop certain kinds of mental disorders.
Psychiatrists examining the interplay between racism and mental health in societies where racism is prevalent have observed, for example, that racism may worsen depression. In a recent review of 10 studies of diverse racial groups in North America, amounting in total to over 15 000 respondents, a positive association between experiences of racism and psychological distress was firmly established (Williams & Williams-Morris 2000).
Racism's influence can also be considered at the level of the collective mental health of groups and societies. Racism has fuelled many oppressive social systems around the world and across the ages. In recent history, racism allowed white South Africans to define black South Africans categorically as "the enemy", and thus to commit acts that they would otherwise have found morally reprehensible.
The extraordinary scale and rapidity of technological change in the late 20th century is another factor that has been associated with the development of mental and behavioural disorders. These technological changes, and in particular the communications revolution, offer tremendous opportunities for enhanced diffusion of information and empowerment of users. Telemedicine now makes it possible to provide treatment at a distance.
But these advances also have their downside. There is evidence to suggest that media portrayals exert an influence on levels of violence, sexual behaviour and interest in pornography, and that exposure to video game violence increases aggressive behaviour and other aggressive tendencies (Dill & Dill 1998). Advertising spending worldwide is now outpacing the growth of the world's economy by one-third. Aggressive marketing is playing a substantial role in the globalization of alcohol and tobacco use among young people, thus increasing the risk of disorders related to substance use and associated physical conditions (Klein 1999).
Chapter 1: A public health approach to mental health :
1,2,3,4
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