Schizophrenia.

The diagnostic criteria for schizophrenia have been extensively changed by the third edition of the Diagnostic and Statistical Manual of Mental Disorders, recently adopted by the American Psychiatric Association (DSM III). To receive this diagnosis, the patient must have onset of illness before age 45 years, have had a chronic course, manifest the presence of characteristic symptoms, such as delusions, hallucinations, or loose associations during a phase of the illness, and have experienced a downhill social and vocational course; affective disorders and organic brain syndrome must be carefully excluded. The utilization of this "narrow" definition has caused a major shift toward increasing the diagnosis of affective disorders and decreasing the diagnosis of schizophrenia in the United States. The etiology of schizophrenia is still uncertain, but recent research has elucidated one subgroup of schizophrenic patients who have subtle indices of neurological damage and a clinical course similar to that found in dementia. Dopamine excess in the mesolimbic system is the predominant inferred cause for the majority of schizophrenia cases, and antipsychotic medications all rely on dopamine receptor blockade for their efficacy. Antipsychotic medications are effective in schizophrenia but are less potent against such negative symptoms as apathy, neglect of personal hygiene, and social withdrawal.