A Public Health Approach to Mental Health. (Chapter One)

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Mental health is as important as physical health to the overall well-being of individuals, societies and countries. Yet only a small minority of the 450 million people suffering from a mental or behavioural disorder are receiving treatment. Advances in neuroscience and behavioural medicine have shown that, like many physical illnesses, mental and behavioural disorders are the result of a complex interaction between biological, psychological and social factors. While there is still much to be learned, we already have the knowledge and power to reduce the burden of mental and behavioural disorders worldwide.

INTRODUCTION

For all individuals, mental, physical and social health are vital strands of life that are closely interwoven and deeply interdependent. As understanding of this relationship grows, it becomes ever more apparent that mental health is crucial to the overall wellbeing of individuals, societies and countries.

Unfortunately, in most parts of the world, mental health and mental disorders are not regarded with anything like the same importance as physical health. Instead, they have been largely ignored or neglected. Partly as a result, the world is suffering from an increasing burden of mental disorders, and a widening "treatment gap". Today, some 450 million people suffer from a mental or behavioural disorder, yet only a small minority of them receive even the most basic treatment. In developing countries, most individuals with severe mental disorders are left to cope as best they can with their private burdens such as depression, dementia, schizophrenia, and substance dependence. Globally, many are victimized for their illness and become the targets of stigma and discrimination.

Further increases in the number of sufferers are likely in view of the ageing of the population, worsening social problems, and civil unrest. Already, mental disorders represent four of the 10 leading causes of disability worldwide. This growing burden amounts to a huge cost in terms of human misery, disability and economic loss.

Mental and behavioural disorders are estimated to account for 12% of the global burden of disease, yet the mental health budgets of the majority of countries constitute less than 1% of their total health expenditures. The relationship between disease burden and disease spending is clearly disproportionate. More than 40% of countries have no mental health policy and over 30% have no mental health programme. Over 90% of countries have no mental health policy that includes children and adolescents. Moreover, health plans frequently do not cover mental and behavioural disorders at the same level as other illnesses, creating significant economic difficulties for patients and their families. And so the suffering continues, and the difficulties grow.

This need not be so. The importance of mental health has been recognized by WHO since its origin, and is reflected by the definition of health in the WHO Constitution as "not merely the absence of disease or infirmity", but rather, "a state of complete physical, mental and social well-being". In recent years this definition has been given sharper focus by many huge advances in the biological and behavioural sciences. These in turn have broadened our understanding of mental functioning, and of the profound relationship between mental, physical and social health. From this new understanding emerges new hope.

Today we know that most illnesses, mental and physical, are influenced by a combination of biological, psychological, and social factors (see Figure 1.1). We know that mental and behavioural disorders have a basis in the brain. We know that they affect people of all ages in all countries, and that they cause suffering to families and communities as well as individuals. And we know that in most cases, they can be diagnosed and treated cost-effectively. From the sum of our understanding, people with mental or behavioural disorders today have new hope of living full and productive lives in their own communities.

This report presents information concerning the current understanding of mental and behavioural disorders, their magnitude and burden, effective treatment strategies, and strategies for enhancing mental health through policy and service development.

The report makes it clear that governments are as responsible for the mental health as for the physical health of their citizens. One of the key messages to governments is that mental asylums, where they still exist, must be closed down and replaced with well-organized community-based care and psychiatric beds in general hospitals. The days of locking up people with mental or behavioural disorders in grim prison-like psychiatric institutions must end. The vast majority of people with mental disorders are not violent. Only a small proportion of mental and behavioural disorders are associated with an increased risk of violence, and comprehensive mental health services can decrease the likelihood of such violence.

As the ultimate stewards of any health system, governments must take the responsibility for ensuring that mental health policies are developed and implemented. This report recommends strategies that countries should pursue, including the integration of mental health treatment and services into the general health system, particularly into primary health care. This approach is being successfully applied in a number of countries. In many parts of the world, though, much more remains to be accomplished.

UNDERSTANDING MENTAL HEALTH

Mental health has been defined variously by scholars from different cultures. Concepts of mental health include subjective well-being, perceived self-efficacy autonomy, competence, intergenerational dependence, and self-actualization of one's intellectual and emotional potential, among others. From a cross-cultural perspective, it is nearly impossible to define mental health comprehensively. It is, however, generally agreed that mental health is broader than a lack of mental disorders.

An understanding of mental health and, more generally, mental functioning is important because it provides the basis on which to form a more complete understanding of the development of mental and behavioural disorders.

In recent years, new information from the fields of neuroscience and behavioural medicine has dramatically advanced our understanding of mental functioning. Increasingly, it is becoming clear that mental functioning has a physiological underpinning, and is fundamentally interconnected with physical and social functioning and health outcomes.

ADVANCES IN NEUROSCIENCE

The World Health Report 2001 appears at an exciting time in the history of neuroscience. This is the branch of science which deals with the anatomy physiology biochemistry and molecular biology of the nervous system, especially as related to behaviour and learning. Spectacular advances in molecular biology are providing a more complete view of the building blocks of nerve cells (neurons). These advances will continue to provide a critical platform for the genetic analysis of human disease, and will contribute to new approaches to the discovery of treatments.

The understanding of the structure and function of the brain has evolved over the past 500 years (Figure 1.2). As the molecular revolution proceeds, tools such as neuroimaging and neurophysiology are permitting researchers to see the living, feeling, thinking human brain at work. Used in combination with cognitive neuroscience, imaging technologies make it increasingly possible to identify the specific parts of the brain used for different aspects of thinking and emotion.

The brain is responsible for melding genetic, molecular and biochemical information with information from the world. As such, the brain is an extremely complex organ. Within the brain, there are two types of cells: neurons and neuroglia. Neurons are responsible for sending and receiving nerve impulses or signals. Neuroglia provide neurons with nourishment, protection and structural support. Collectively there are more than one hundred billion neurons in the brain, comprising thousands of distinct types. Each of these neurons communicates with other neurons via specialized structures called synapses. More than one hundred distinct brain chemicals, called neurotransmitters, communicate across these synapses. In aggregate, there are probably more than 100 trillion synapses in the brain. Circuits, formed by hundreds or thousands of neurons, give rise to complex mental and behavioural processes.

During fetal development, genes drive brain formation. The outcome is a specific and highly organized structure. This early development can also be influenced by environmental factors such as the pregnant woman's nutrition and substance use (alcohol, tobacco, and other psychoactive substances) or exposure to radiation. After birth and throughout life, all types of experience have the power not only to produce immediate communication between and among neurons, but also to initiate molecular processes that remodel synaptic connections (Hyman 2000). This process is described as synaptic plasticity, and it literally changes the physical structure of the brain. New synapses can be created, old ones removed, existing ones strengthened or weakened. The result is that information processing within the circuit will be changed to accommodate the new experience.

Prenatally, during childhood and through adulthood, genes and environment are involved in a series of inextricable interactions. Every act of learning -- a process that is dependent both on particular circuits and on the regulation of particular genes -- physically changes the brain. Indeed, the remarkable evolutionary success of the human brain is that, within certain limits, it remains plastic across the lifespan. This recent discovery of lifelong synaptic plasticity represents a shift away from earlier theories that held that the structure of the adult brain is static (see Box 1.1).

As notable as discoveries to date have been, neuroscience is yet in its infancy. Future advances will provide a more complete understanding of how the brain is related to complex mental and behavioural functioning. Innovations in brain imaging along with neuropsychological and electrophysiological studies will permit real time cinema of the nervous system at work. Imaging will be combined with a growing ability to record from a large number of neurons at once; in this manner, it will be possible to decode their language. Other advances will be based on progress in genetics. An initial working draft sequence of the human genome is available in the public domain (at http://www.ornl.gov/hgmis/). One of the important uses of genomic information will be to provide a new basis for developing effective treatments for mental and behavioural disorders.

Another important tool that will enhance understanding of the molecular building blocks of development, anatomy, physiology and behaviour is the generation of genetically altered mice. For nearly every human gene there is an analogous mouse gene. This conservation of gene function between humans and mice suggests that mouse models will yield fundamental insights into human physiology and disease (O'Brien et al. 1999). Many laboratories around the world are involved in systematically inserting or deleting identified genes, and others are embarking on projects of generating random mutations throughout the mouse genome. These approaches will help connect genes with their actions in cells, organs and whole organisms.

Integration of the research results of neuroimaging and neurophysiology with those of molecular biology should lead to a greater understanding of the basis of normal and abnormal mental function, and to the development of more effective treatments.

ADVANCES IN BEHAVIOURAL MEDICINE

Advances have occurred not only in our understanding of mental functioning but also in the knowledge of how these functions influence physical health. Modern science is discovering that, while it is operationally convenient for purposes of discussion to separate mental health from physical health, this is a fiction created by language. Most "mental" and "physical" illnesses are understood to be influenced by a combination of biological, psychological and social factors. Furthermore, thoughts, feelings and behaviour are now acknowledged to have a major impact on physical health. Conversely, physical health is recognized as considerably influencing mental health and well-being.

Behavioural medicine is a broad interdisciplinary area that is concerned with the integration of behavioural, psychosocial, and biomedical science knowledge relevant to the understanding of health and illness. Over the past 20 years, mounting scientific evidence from the field of behavioural medicine has demonstrated a fundamental connection between mental and physical health (see Box 1.2). Research has shown, for example, that women with advanced breast cancer who participate in supportive group therapy live significantly longer than women who do not participate in group therapy (Spiegel et al. 1989), that depression predicts the incidence of heart disease (Ferketich et al. 2000), and that realistic acceptance of one's own death is associated with decreased survival time in AIDS, even after controlling for a range of other potential predictors of mortality (Reed et al. 1994).

How do mental and physical functioning influence each other? Research has pointed to two main pathways through which mental and physical health mutually influence each other over time. The first key pathway is directly through physiological systems, such as neuroendocrine and immune functioning. The second primary pathway is through health behaviour. The term health behaviour covers a range of activities, such as eating sensibly, …