Psychiatric epidemiology

Psychiatric epidemiology is a field which studies the causes (etiology) of mental disorders in society, as well as conceptualization and prevalence of mental illness. It is a subfield of the more general epidemiology. It has roots in sociological studies of the early 20th century. However, while sociological exposures are still widely studied in psychiatric epidemiology, the field has since expanded to the study of a wide area of environmental risk factors, such as major life events, as well as genetic exposures. Increasingly neuroscientific techniques like MRI are used to explore the mechanisms behind how exposures to risk factors may impact psychological problems and explore the neuroanatomical substrate underlying psychiatric disorders.

Sociological studies of the early 20th century can be regarded as predecessors of today's psychiatric epidemiology. These studies investigated for instance how suicide rates differ between Protestant and Catholic countries or how the risk of suffering from schizophrenia is increased in neighborhood characterized with high levels of social isolation. After World War 2 researchers began using community surveys to assess psychological problems. By the 1980s the development of new diagnostic assessment instruments and reliable criteria for mental disorders given by the DSM-3 began a trend to estimating the prevalence of mental disorders next to symptoms.

As an example, in an attempt to measure the prevalence of mental illness in the United States, Lee Robins and Darrel A. Regier conducted a study called the Epidemiological Catchment Area Project which surveyed samples of the general population at five sites across America. In the study, it was found that about a third of all Americans suffer from mental illness at some point in their lives. This statistic is often referred to as lifetime prevalence.

Today, epidemiological studies focus on the etiology of mental disorders, i.e. the identification and quantification of causes underlying psychiatric problems and their mechanisms, rather than mere estimation of prevalence. It is not ethically possible to experimentally expose study participants to stressors suspected to cause psychiatric disorders, thus epidemiological techniques are required to study the etiology. For this purpose longitudinal studies, which follow children and adults for a long period of time, often for many years, are particularly useful. These allow the study of naturally occurring exposures and how they affect changes in psychiatric symptoms. Two notable historical studies focusing on etiology are the Dunedin Multidisciplinary Health and Development Study and the Christchurch Health and Development Study. These studies began in the 70's and studied the impact of perinatal problems, genetic variants, sexual abuse and other adverse exposures on psychological problems in childhood and later in adulthood.

...
Wikipedia