Mental illness

Synonyms in a broader sense

mental illness, mental abnormality, mental disease, vulg. : mental illness

Definitions and general information

The term “mental disorder” is the term currently used in professional circles to describe diseases of the human psyche. It was chosen because it is assumed to be less (devaluation) than terms such as “illness” or “disease” and to avoid stigmatization of those affected, which has frequently occurred in the past. On the following pages, however, the terms “mental illness”, “mental abnormality” and “mental illness” are also used without any evaluation.

The human psyche is difficult to grasp in its entirety, and accordingly it is also difficult to define disorders of the psyche concisely. One reason for this may be that a considerable proportion of these disorders elude the observer or examiner because they take place “inside” the person concerned. In contrast to somatic, i.e. physical, medicine, “measured values” are generally lacking to objectify such disorders. The delicate definition of the psychologically “normal” also plays a considerable role, which is largely determined by the ideas and tolerance of the respective society. For this reason, psychiatry, as the discipline of modern medicine that deals with mental disorders, has a not inconsiderable overlap with the social sciences.


Mental disorders are generally frequent, some studies assume that every second person at some point in life shows at least mild symptoms of mental abnormality. The frequency of disorders in need of treatment is given as approx. 1/10 for Germany. A mental disorder is one of the most common causes of treatment by general practitioners and a reason for (temporary) disability.


Science has identified many influencing factors for the development of a mental disorder, one speaks of a “multifactorial genesis”. It is hardly possible to structure these influencing factors systematically without gaps and overlapping areas. The following list is therefore rather exemplary.

  • Physical causes: metabolic disorders (e.g. hypothyroidism or hyperthyroidism), brain damage e.g. due to accidents, diseases or infections of the brain such as Alzheimer’s disease or meningitis, poisoning (alcohol, drugs), disorders of the messenger metabolism in the brain, storage diseases such as M. Wilson.
  • “Psychological causes”: traumatic experiences (PTSD) e.g. experience of violence, serious illness, stressful life events.
  • Genetic causes: For a number of mental disorders, a familial clustering has been demonstrated in recent years, suggesting the presence of hereditary risk factors.