Differentiating organic from functional psychosis.

Psychosis is not pathognomonic of psychiatric illness. It is simply a nonspecific cluster of signs and symptoms that may occur in a broad array of medical, neurologic and surgical disorders or as a consequence of pharmacologic treatment, substance abuse or the withdrawal of drugs and alcohol. Psychoses are classified as organic or functional mental disorders. Organic disorders with psychosis are caused by structural defects or physiologic dysfunction of the brain. The causes of functional disorders have not yet been identified. Psychoses are also categorized as effective or nonaffective in character. Affective and nonaffective psychoses may be associated with either organic or functional disorders.