(A) the definition of the epidemiology of mental illness

Psychiatric epidemiology is a field of psychiatry that introduces modern epidemiology and health statistics into clinical medicine, from the diagnosis and treatment of individual patients to the study of the causes and distribution of mental disorders and mental health-related conditions in the population; Explore the etiology, pathogenesis, clinical manifestations, diagnosis and treatment, prevention and prognosis of mental illness, focusing on group characteristics; So as to formulate countermeasures and measures to prevent, control and eliminate these mental diseases and promote health, and evaluate their effects through scientific design, measurement and evaluation methods.

(2) A brief history of the epidemiological development of mental illness.

In the past half century, epidemiology has developed rapidly, and the research content has expanded from infectious diseases and acute diseases to non-infectious diseases and chronic diseases, as well as the health problems of the population. The research of psychiatry has long been mainly limited to the diagnosis and treatment of individuals with clinical mental illness. With the change of medical model, to explore the etiology, pathogenesis and clinical manifestations of mental illness, it is necessary to expand the research scope from sick individuals to sick groups and link the natural environment and social environment with mental illness. Therefore, it is natural to apply epidemiological research methods to the study of psychiatry, forming an interdisciplinary subject of psychiatry.

The clue of epidemiology of mental illness can be traced back to the beginning of19th century, when some European countries conducted demographic surveys on mental patients in order to estimate the number of mental hospitals. By the end of 19, due to various opportunities, such as some European countries legislating to provide care for mental patients in the community, it is necessary to know the number, condition and needs of mental patients. Some psychiatrists need to apply the theory of medical genetics to collect relevant information from the community population to study the pedigree of mental patients. The improvement of methodology makes the research results more authentic and reliable, which promotes the development of mental disease epidemiology. American social psychiatrist Dohrenwend divides the prevalence of mental illness into three stages: the first stage is from the beginning of this century to the Second World War, and the research method in this period is only to diagnose mental patients by using medical records and main insiders. The second stage is from World War II to the end of 1970s. During this period, the research method is to diagnose the case by talking directly with all the objects in the community sample. The third stage is from the early 1980s to the present. Influenced by the development of genetics, psychopharmacology, psychobiology, especially psychopathology and social sciences, with the improvement of methodology, the epidemiology of mental diseases has developed rapidly. At present, due to the improvement of sampling methods, the development of screening tools for mental illness with good validity and reliability, the use of unified classification and diagnostic criteria, and the use of standardized mental state examination tools, the research on mental illness has reached satisfactory consistency requirements, and can provide the distribution characteristics of mental illness in a certain range more objectively, which is of great significance to the research and development of psychiatry, thus promoting the development of mental illness epidemiology.

The epidemiology of mental illness in China began in the late 1940s. Although large-scale mental illness surveys were conducted in some areas of China in the 1950s and 1970s, such as Lin's 1953 and 1973, which applied American diagnostic criteria to conduct large-scale epidemiological surveys of mental illness in Taiwan Province Province, due to methodological limitations, the results of these surveys are not comparable and there is a lack of communication at home and abroad. In order to be in line with the international epidemiological study of mental illness and provide the distribution characteristics and risk factors of mental illness in a certain range more objectively, China introduced international advanced investigation methods in 1982, and organized the first national collaborative epidemiological survey of mental illness in 12 area, and obtained epidemiological data of mental illness from a large sample of people in history, which greatly improved the epidemiological research level of mental illness in China. Starting from 1993, a second survey was conducted in seven of the above-mentioned 12 areas, and the same survey methods and procedures were adopted to understand the dynamic changes of mental illness in the process of reform, opening up, industrialization and urbanization in China. These studies provide useful information for China to make long-term mental health planning and further explore the causes of mental illness.

(3) Epidemiological characteristics of mental illness

The epidemiological characteristics of mental illness are firstly the characteristics of psychiatry. The discipline foundation of this discipline is psychiatry, and its task is to explore the etiology, risk factors, diagnosis, treatment and prognosis of major mental diseases that endanger people's health by using the scientific methods of modern psychiatry research. Therefore, this subject should be based on the clinical practice of psychiatry and provide innovative methodology for clinical research, diagnosis and treatment. At the same time, the research object of mental illness epidemiology is sick individuals and groups, so it is necessary to break through the limitations of traditional hospital-based psychiatric clinical medicine, expand to population-based community research, and highlight the macro-research characteristics of epidemiology. Applying epidemiological methods to the study of psychiatry is of great significance and value for the early detection and effective prevention and treatment of mental diseases, as well as for understanding the nature and law of the occurrence, development and prognosis of diseases.

(4) The research content of the epidemiology of mental illness.

The research content of mental illness epidemiology first describes the incidence, morbidity and mortality of mental illness in different time, region and population, as well as mental state and social function defects. By comparing the distribution of diseases in different time, different regions and different people, we can find out the reasons that affect the distribution and explore the risk factors, epidemic factors and causes of diseases. According to the results of population research, estimate the risk of a certain factor that makes an individual suffer from a certain disease; Through the research and evaluation of the natural history of mental illness, it involves the susceptible factors, protective factors (social factors, family factors), prognostic factors and life events of mental illness. On the basis of the above research, study and formulate preventive countermeasures and measures for mental illness, and evaluate their effects.

(5) Research methods of the epidemiology of mental illness.

According to the classification of current epidemiological research methods, the epidemiological research methods of mental illness can be divided into three categories: observation, experiment and theoretical and methodological research. Observation method includes descriptive research and analytical research, and experimental method includes clinical trial and community trial. The research of theory and method is to establish a mathematical model based on the data obtained from epidemiological investigation to clarify the epidemiological law of mental illness. The epidemiology of mental illness also widely uses psychological theory and measurement methods to study the mental illness and mental health of the population, which is a special research method of this discipline.

(six) the relationship between the epidemiology of mental illness and related disciplines.

The epidemiology of mental illness is an interdisciplinary subject, which is closely related to many disciplines. First of all, this subject is not only a major of clinical medicine as psychiatry, but also a main part of preventive medicine as epidemiology. The two complement each other. The task of clinical medicine is to diagnose and treat sick individuals, while epidemiology should not only study sick individuals and groups, but also study people who are not sick and environmental factors, and analyze the relationship between diseases and various natural and social factors, so as to formulate prevention and control countermeasures and evaluate their effects. Therefore, when diagnosing diseases and discussing the causes, we should have the clinical knowledge of mental illness, master the basic theories and research methods of epidemiology, apply epidemiological knowledge and combine clinical experience to explore the crowd phenomenon and causes of mental illness.

The epidemiology of mental illness is closely related to basic medicine. In the process of finding and confirming the cause, this subject inevitably involves many basic disciplines in basic medicine, such as biochemistry, physiology, biophysics, pathology, immunology, genetics and so on. The knowledge of each subject complements each other, provides clues and promotes each other's development.

In addition, due to the expansion of the epidemiological research field of mental illness, it is inevitable to contact with many disciplines and technical methods such as environmental science and humanities when investigating and analyzing the epidemic process and the distribution law of diseases. As we all know, with the change of medical model, people pay more and more attention to the influence of social factors, psychological factors and human behavior on mental illness, which promotes the mutual penetration of social science disciplines such as behavior, sociology and psychology and the epidemiology of mental illness, and makes people's understanding of the nature of mental illness continue to develop. Therefore, the term social psychiatry is also adopted in academic circles at present.

Second, the development of epidemiology of mental illness abroad

(A) the epidemiological research results of mental illness abroad

Worldwide, with the deepening of psychiatric theory and the improvement of methodology, more and more real and reliable data have been obtained in the epidemiological study of mental diseases in the past half century. In recent years, different countries have conducted large-scale epidemiological surveys of mental diseases in various communities with different research methods, but the epidemiological data of various mental diseases are not the same. Kessler et al. in America (1994) reported the results of a community survey. The stratified samples of 8098 people 15-54 years old were examined by the revised description of the international diagnostic review organization. It is estimated that the prevalence rate of non-affective psychosis (including schizophrenia, schizophrenia, schizophrenia, paranoia and atypical psychosis) is 5‰ within one year. Kendler et al. (1996) reported that the lifetime prevalence of schizophrenia and schizophrenia-like psychosis was 1.3%, and the lifetime prevalence of all non-emotional mental disorders was 2.2%. The lifetime prevalence rate of schizophrenia and schizophreniform psychosis diagnosed by clinicians is 0.2%, and the lifetime prevalence rate of all non-emotional mental disorders is 0.7%. The survey also found that all non-emotional mental disorders diagnosed by clinicians are significantly related to low income, unemployment, singles, divorce, separation and urban living. This shows that the estimation of the lifetime prevalence rate of mental illness in community population samples is greatly influenced by examination methods and diagnostic criteria, and the conclusion is that the correct examination of mental illness in epidemiological samples depends on the judgment of clinicians. Welch et al. (1998) investigated 9064 residents aged 16-75 living in England, Wales and Scotland, and found that low family income, low material living standard and low social class were significantly related to mental disorders, but the gender difference in the prevalence of mental disorders could not be explained by the difference in social roles between men and women. Bijl et al. (1998) in the Netherlands reported a prospective study on the prevalence of mental illness in 7076 community people aged 18-64. The results showed that according to the diagnostic criteria of DSM-III-R III-R of American Psychiatric Association, 4 1.2% of people under 65 had experienced emotional disorder, anxiety disorder and eating.

For all kinds of mental disorders, in recent years, the research in various countries has achieved fruitful results, among which schizophrenia is the mental disease with the longest research time, the widest research scope and the deepest research. Jablensky of Australia (1997) pointed out that schizophrenia is a lifelong disease with low incidence but relatively high prevalence. Since Kraepelin( 1896) first described schizophrenia as a disease entity called "early onset dementia", epidemiological studies since the beginning of this century have obtained remarkably consistent estimates of the prevalence, incidence and lifelong harm of schizophrenia in different populations and regions. According to the survey data of the epidemiological catch-up area (ECA) 1988 of the National Mental Health Center of the United States, after unified diagnostic criteria and standardized psychiatric examination training, the prevalence rate of schizophrenia is 6‰ in one month and 13‰ in half a year. Long-term studies have confirmed that both environmental and genetic factors have etiological effects on schizophrenia. Jones( 1998) proposed that the progress of molecular genetics revealed the linkage on chromosomes 6, 8 and 32, which provided evidence for finding genetic genes on chromosomes. Myles et al. (1999) published the survey results in the relatively isolated island countries of Palau and China. 13,750 adults 15 years old, the lifetime prevalence rate of schizophrenia is 1.99%, including 2.77% for males and 65,438+for females. German hafner and others pointed out that 12-60-year-old adults are one in ten thousand likely to suffer from schizophrenia, and the main onset age is 20-35 years old. The frequency and severity of late-onset schizophrenia in women are greater than that in men. Brewin( 1997) reported that the incidence of schizophrenia in Nottingham, England increased slightly from 2.49‰ to 2.87‰ in 1978-80 and 1992-94. WHO (World Health Organization) analyzed the cooperative research results of global 10 centers, and pointed out that the incidence of schizophrenia in different regions and countries is similar. In short, worldwide research shows that there is no obvious difference in the onset time and geographical distribution of schizophrenia; The age distribution is mainly the first onset in young adults, with gender differences; Family economic level and social class are negatively correlated with the prevalence of schizophrenia.

In the 4th century BC, the word "melancholy" appeared in the works of Hippocrates. Falreth, Kahlbaum( 1882) and Kraepelin( 1896) in France have made great contributions to affective disorder in history. In the middle of this century, Leonhard of Germany (1957) put forward the theory of bipolar disorder and unipolar affective disorder, arguing that heredity is an important factor to distinguish unipolar affective disorder from bipolar affective disorder. The epidemiological studies of early affective disorders are all classified as manic depression, but not as unipolar and bipolar affective disorders, and there is no consistent diagnostic standard, but the results are close. In 1980s, western countries gradually adopted unified diagnostic criteria and standardized mental examination. Taking the United States as an example, the ECA survey conducted by the National Mental Health Center of the United States found that the six-month prevalence rate of various emotional disorders was 0.4%-4.6% for men and 0.4%-8.2% for women after training in unified diagnostic criteria and standardized mental examination. Eaton (1997) reported the tracking results of ECA in Baltimore, USA, and rechecked 198 1 920 people in line from 1993 to 1996. The estimated incidence of major depression is 3. Ohayon( 1999) reported the results of a survey of 4972 people, representing the total population of Britain from 1994. At the time of examination, the prevalence rate of depression was 5%, 5.9% for women, which was significantly higher than 4.2% for men. Kitamura (1998) reported that the lifetime prevalence rate of major depression in Japan was 19%, and the prevalence rate of women was twice that of men. Cho( 1998) reported the survey results of 37 1 1 person in Korea. The time-point prevalence rate of depression was 6.8% in men and 10.4% in women. Szadoczky( 1998) reported the results of a survey of the population aged 8-64 in Hungary/kloc-0. The lifetime prevalence rate of major depression is 15. 1%, the male-female ratio is 1:0.37, and bipolar disorder is 5. 1%, which are similar. The prevalence rates of major depression in 1 year and 1 month were 7. 1% and 2.6% respectively, and the prevalence rate of manic episode was 0.9% and 0.5% respectively. The peak of both diseases is 15- 19 years old, and the second peak of major depression is 45-50 years old. Brand, Canada (1997) summarized the epidemiology of affective disorder, and thought that in recent 15 years, many researchers have made great progress in applying standardized methods in different countries, cultures and races, and the proportion of major depression has increased. Like bipolar disorder, it occurs in younger age groups. Research conclusions all over the world agree that emotional and mental disorders are a major public health problem due to difficulties in understanding, diagnosis and treatment.

With the trend of aging in developed countries, the absolute number of patients with Alzheimer's disease, AD and other Alzheimer's diseases has increased, which has become a major social problem and medical care content in many developed countries. Most epidemiological data show that the prevalence of dementia is 4-6% in people over 65 years old and as high as 20% in people over 80 years old. Hendrie( 1998) reported that the prevalence of dementia in people aged 65 and over in North America was 6- 10%, of which AD accounted for two thirds. Therefore, the United States and Britain have listed AD as the key research project of geriatric diseases, which makes the status and importance of AD in geriatrics and geriatric psychiatry increasingly valued.

In addition, there are many studies on neurosis, especially non-serious mental disorders such as obsessive-compulsive neurosis, panic disorder, personality disorder, mental retardation, etc. However, due to methodological limitations, some epidemiological data are not comparable.

(B) the development trend of foreign mental illness epidemiology

At present, the international diagnosis of mental illness is mainly the International Classification of Diseases (10th Edition, ICD- 10) and the Diagnostic and Statistical Manual of Mental Disorders (4th Edition, DSM-). ICD- 10 is an international diagnostic standard and classification system for mental illness recommended by WHO, and experts spare no effort to apply it to all countries, cultures and people. After nearly ten years of efforts, many countries have adopted ICD- 10 for clinical diagnosis and epidemiological research. DSM-Ⅳ is the diagnostic standard and classification system of mental illness in the United States. It is widely used in English-speaking countries such as Britain and Australia, and has achieved a lot. With the development of international research on mental illness, more and more psychiatrists realize that the universal diagnosis and classification system, standardized mental state examination tools and unified psychiatric vocabulary play a vital role in promoting the international exchange of psychiatric research information and the extensive and in-depth research on mental illness. Therefore, both the WHO expert in charge of ICD- 10 and the editor of DSM-IV in the United States are committed to the convergence of the two diagnostic and classification systems, and an expert group responsible for cross-cultural research has been established. In addition, psychiatrists all over the world have made many comparative studies on the validity and reliability of ICD- 10 and DSM-IV, and found that the two diagnosis and classification systems have satisfactory consistency for most mental diseases. These achievements laid a methodological foundation for the international epidemiological study of mental illness. At present, the diagnosis and classification system of mental illness is becoming more and more mature, but the existing problem is that the screening tools suitable for community population research are not satisfactory, so it is necessary to study and develop standardized screening methods that can be applied to epidemiological research. In recent years, WHO has continuously organized multi-center collaborative research on mental illness in various countries, aiming at not only promoting the use of standardized diagnosis and classification standards, but also obtaining epidemiological data of mental illness in various countries around the world, exploring the causes and risk factors of mental illness, studying the influence of sociology, demography, ecology, social environment and psychosocial factors on mental illness, and applying epidemiological methodology to promote the in-depth study of mental illness.

At present, in addition to a lot of descriptive research, the epidemiological research on mental illness in countries all over the world also includes analytical research on the causes of various mental diseases, natural history research, intervention research on treatment and rehabilitation, and special methods of epidemiological research on mental diseases. Sociology, psychology, genetics, molecular biology, psychopharmacology and other related disciplines, as well as the latest statistics and computer technology are combined with the epidemiological study of mental illness in more and more fields, which promotes the continuous development of mental illness research.

Third, the development of the epidemiology of mental illness in China.

(A) the development status of the epidemiology of mental illness in China.

The research on community mental health and epidemiology of mental illness in China began at the first national conference on prevention and treatment of mental illness in 1958, and a three-level prevention and treatment network for mental illness was established in urban and rural areas in the 1970s. 1986 The convening of the second mental health conference has further promoted the research on the epidemiology of mental health and mental diseases in China. Although large-scale mental illness surveys were conducted in some areas in the 1950s and 1970s, the results were not comparable due to the methods of screening and diagnosis.

With the reform and opening up and scientific and technological exchanges, Chinese psychiatrists have introduced the advanced investigation methods of international epidemiological research on mental diseases into China. 1982 under the leadership of the Ministry of health, the first national epidemiological survey of mental illness was organized in 12 areas. According to the diagnosis and classification standards of ICD and DSM, a unified sampling method and investigation procedure, as well as a screening tool for mental illness, standardized examination methods and diagnostic standards with satisfactory validity and reliability were formulated. In the implementation stage of on-site investigation, the investigators will be trained in a unified way; The multi-stage sampling method of cluster, stratification and random stage is adopted for sample extraction. Through large-scale investigation, the time-point prevalence rate of various mental diseases is 10.54‰, and the lifetime prevalence rate is 12.69 ‰. Among them, the time-point prevalence rate of schizophrenia is 4.75‰, the lifetime prevalence rate is 5.69‰, and the time-point prevalence rate in cities is 6.06‰, which is significantly higher than that in rural areas (3.42 ‰). The time-point prevalence rate of affective mental disorder is 0.37‰, and the lifetime prevalence rate is 0.76‰. In addition, the survey also found some related factors, such as the prevalence of schizophrenia and the economic level is negatively correlated. This survey provides some basic data of mental illness in China, and also provides the methodology of national epidemiological survey of mental illness, thus greatly improving the level of epidemiological research of mental illness in China.

During the period of 1993, the second large sample survey was conducted in seven of the above-mentioned 12 areas using the same survey methods and procedures. The results showed that the time-point prevalence rate of various mental disorders (excluding neurosis) in seven regions was 1 1. 18‰, and the lifetime prevalence rate was 1993. Followed by mental retardation, the prevalence rate is 2.70 ‰; The time-point prevalence rate of affective mental disorder is 0.52‰, and the lifetime prevalence rate is 0.83 ‰. The prevalence of alcohol dependence increased the most, with a prevalence rate of 0.68‰. In addition, the prevalence of Alzheimer's Harmo's disease is 0.36‰. The results of these two national large-scale epidemiological surveys of mental disorders show that there is no significant difference between the lifetime prevalence rate of various mental disorders (except neurosis) in seven regions and the standardized 1982. The prevalence of schizophrenia in cities is higher than that in rural areas, and the population with the lowest economic level has the highest prevalence. The results suggest that schizophrenia is the key disease for prevention and research in China, and mental retardation ranks second in urban and rural areas in China at present, and it is also the key disease for prevention and rehabilitation, while alcohol dependence, affective disorder and Alzheimer's Harmo's disease need to be strengthened for prevention and research. It is worth noting that the prevalence of some mental diseases in the two surveys is obviously lower than that in western countries, such as emotional disorders and personality disorders, which have aroused widespread concern of scholars at home and abroad. The reason may be related to the understanding of these mental diseases, diagnostic classification standards and cultural differences.

In addition, descriptive and analytical epidemiological studies on mental illness have been carried out in China. According to the data of large-scale epidemiological survey of mental illness conducted by Ru Lin in Taiwan Province Province 1953 and 1973, the prevalence of mental illness is negatively correlated with social economy and education level (1). 1988 An epidemiological survey of mental retardation among children aged 0- 14 in eight provinces and cities showed that the prevalence rate was 1.20‰, 0.70‰ in cities,1.4/kloc-0 ‰ in rural areas and/kloc-0 ‰ in boys. At the same time, case-control study method is also used to study the risk factors and behavior problems of ADHD in children. In recent 10 years, China introduced foreign examination methods to investigate the prevalence and incidence of senile dementia, and conducted a case-control study on the risk factors of Alzheimer's disease. The results showed that family history of dementia and severe mental illness in first-degree relatives were the main risk factors of dementia, which provided evidence for genetic theory. In addition, the successful example of experimental epidemiological research is the intervention study of iodized salt to prevent mental retardation in endemic goiter areas. Investigation shows that widespread and long-term use of iodized salt in iodine-deficient areas can significantly reduce the mental retardation of children caused by endemic cretinism. In a word, the epidemiological study of mental illness in China has developed rapidly with the progress of related disciplines.

(2) Challenges faced by the epidemiology of mental illness in China.

The epidemiology of mental illness in China is facing the same challenge as the progress of this discipline in the world, that is, organically combining psychiatry with epidemiology. If the study of mental illness is to expand from the diagnosis and treatment of individual patients to the study of the causes and distribution of mental disorders and mental health-related conditions in the population, and explore the clinical laws of mental illness such as etiology, pathogenesis, clinical manifestations, diagnosis and treatment, prevention and prognosis, it is necessary to study the group characteristics, which inevitably requires the introduction of modern epidemiology and health statistics methodology, and the adoption of formal design, measurement and evaluation methods for research. However, the application of classical epidemiological methods to the study of mental illness is often limited by the multiplicity of causes, the uncertainty of symptoms, the multi-axis of diagnosis and the complexity of treatment. Epidemiological research needs representative, random and comparable survey data, but it is sometimes difficult to realize these principles among mental patients because of the uncooperative research subjects. In addition, many classification and diagnosis methods of mental illness are developed under the background of western culture. Introducing them into China will undoubtedly lead to the conflict of cultural differences and the influence of different ethnobiology. In order to ensure the authenticity and reliability of the research conclusions, it is necessary to apply epidemiological theories and methods to China, the methodology of international mental illness research, so as to promote the clinical and community research of mental illness in China. Therefore, the goal of mental illness epidemiology in China is to integrate with international advanced research methods and improve the overall level of the discipline.

Fourthly, the prospect of the epidemiology of mental illness.

In 2000, WHO proposed that everyone should enjoy health, including physical health and mental health. With the development of social economy, science and technology and the improvement of living standards, human beings put forward higher requirements for physical health and quality of life. Therefore, medical experts, researchers and government agencies all over the world attach great importance to the prevention and treatment of mental illness, and put more and more energy into strengthening the research on the etiology and pathogenesis of mental illness in order to improve the level of prevention and rehabilitation. According to the report of Sartorius 1997, President of the World Psychiatric Association, at the regional meeting of the World Psychiatric Association held in Beijing, the priority areas of mental health work in developing countries are to promote mental health, prevent and treat mental and neurological disorders, recover from mental illness and mental disability, and promote psychosocial development. This development trend clearly shows that the research object of mental illness will inevitably expand from clinical individuals to community groups. Through epidemiological research methods, the causes and laws of the disease are discussed, so as to formulate countermeasures and measures to prevent, control and eliminate diseases and promote health, and evaluate their effects through scientific methodology. The combination of medicine with related natural science and social science is the inevitable trend of the development of contemporary mental illness epidemiology.

Psychiatrists generally believe that dementia, schizophrenia and depression are the mental disorders that have the greatest impact on social and economic development and the deepest harm to personal health and family life at the end of the 20th century. On the basis of psychiatry and basic medicine, we need to apply descriptive and analytical research methods, experimental methods and theoretical and methodological research in classical epidemiological observation methods to the research on the occurrence and development of diseases, causes and risk factors, treatment and prevention, strengthen international information exchange and research cooperation, promote the continuous improvement of mental health, and develop the theory and practice of social psychiatry.