Beginning of Essay
are psychological and behavioral syndromes that deviate significantly from those typical of human beings enjoying good mental health. In general, a mental disorder involves present distress or impairment in important areas of functioning. Such deviations in thoug ....

Middle of Essay
.... The division of into classes is still inexact, and classification varies from country to country. For official record-keeping purposes, most countries follow the International Classification of Diseases of the World Health Organization (WHO). For clinical use in the U. S., the American Psychiatric Association in 1980 adopted a third edition of its Diagnostic and Statistical Manual (DSM-III); an extensive revision (DSM-III-R) was issued in 1987. Most classification systems recognize childhood disorders (including mental retardation) as separate categories from adult disorders. Most distinguish between organic, somatically caus ....