Mental illness, also known as psychiatric disease, is any disorder characterized by abnormal function of the higher centers of the brain responsible for thought, perception, mood, and behavior, in which organic disease has been eliminated as a possible cause. The borderline between disease and the range of normal variability is indistinct and may be determined by cultural factors. Crime may result from mental disease, but modern Western society is careful to eliminate it as much as possible before subjecting a criminal to justice. Mental disease has been recognized since ancient times and both Hippocrates and Galen evolved theories as to its origins; but in many cultures, over the centuries, madness has been equated with possession by evil spirits and sufferers were often treated as witches. In the 15th century, Paracelsus proposed that the Moon determined the behavior of mad people (hence "lunacy"), while in the 18th century Mesmer favored the role of animal magnetism (from which hypnosis is derived). The first humane asylum for the mentally ill was founded in Paris by Pinel (1795). Originally only socially intolerable cases were admitted to such hospitals, but today voluntary admission is more common. The Viennese school of psychology, in particular Sigmund Freud and his pupils, emphasized the importance of the past, especially childhood experience, sexual attitudes, and other functional factors. Behavior therapy, psychoanalysis, and psychotherapy derive from this school. On the other hand, the influence of subtle organic factors (e.g., brain biochemistry) was favored by others; this led to the use of lobotomy, shock therapy, and drugs.
Mental illness may be classified into psychosis, neurosis, and personality disorder. Schizophrenia is a psychosis causing disturbance of thought and perception in which mood is characteristically flat and behavior withdrawn. Features include: auditory hallucinations; delusions of person, of surroundings and other people (e.g., suspicion of conspiracy in paranoia); blocking, insertion, and broadcasting of thought, and knight's-move thinking, or nonlogical sequence of thinking. Conversation lacks substance and may be in riddles or neologisms; speech or behavior may be imitative, stereotyped, repetitive, or negative. Phenothiazine drugs, especially chlorpromazine and long-acting analogues, are particularly valuable in schizophrenia.
In affective psychoses, disturbance of mood is the primary disorder. Subjects usually exhibit depression with loss of drive and inconsolably low mood, either in response to situation (exogenous) or for no apparent reason (endogenous). Loss of appetite, constipation, and characteristic sleep disturbance also commonly occur. Antidepressants and shock therapy are valuable, but psychotherapy may also be needed. In hypnomania or mania, excitability, restlessness, euphoria, ceaseless talk, flight of ideas, and loss of inhibitions occur. Financial, sexual or alcohol excesses may result. Chlorpromazine, haloperidol, and lithium are effective. Neuroses include anxiety, pathological exaggeration of a physiological response. This may coexist with depression but responds to benzodiazepines (Valium) and psychotherapy. Obsessional and compulsive neuroses, manifested by extreme habits, rituals, and fixations (which may be recognized as irrational); phobias, excessive and inappropriate fears of objects or situations (e.g., agoraphobia), and hysteria are helped by behavior therapy. Psychopathy is a specific disorder of personality characterized by failure to learn from experience. Irresponsibility, inconsiderateness, and lack of foresight result, and may lead to crime. Other personality disorders are exhibited by a variety of people, often with unstable backgrounds, who seem unable to cope with the realities of everyday adult life. In sexual disorders with antisocial or perverse sexual fixations, behavior therapy may be of value.