Epidemiology, etiology, diagnosis, and treatment of schizophrenia.

The epidemiology, etiology, diagnosis, and treatment of schizophrenia are reviewed. In the United States, at least 1 in every 100 persons is afflicted with schizophrenia. The theory that schizophrenia is a biochemical disorder has gained wide acceptance, although none of the etiological theories are conclusive. Criteria contained in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, are most commonly used to diagnose schizophrenia. Accuracy in diagnosing schizophrenia is critical because the treatments and prognoses for different types of psychoses can vary considerably. Treatment primarily involves the use of antipsychotic drugs, which are thought to act by blocking central dopamine receptors. The classical antipsychotics are the phenothiazines; of these, the prototype is chlorpromazine. Other classes of antipsychotics are the thioxanthenes, butyrophenones, dihydroindolones, dibenzoxazepines, diphenylbutylpiperidines, and dibenzodiazepines. Selecting an appropriate agent involves consideration of adverse effects, dosage forms, and the agent's ability to relieve target symptoms. Adverse effects of these agents include sedation, extrapyramidal effects, and anticholinergic effects. Tardive dyskinesia is a serious, irreversible condition associated with long-term antipsychotic therapy. Clozapine, a newer atypical antipsychotic, has been shown to be more effective than chlorpromazine and haloperidol and seems to cause few neurological adverse effects. Treatment of schizophrenia has not changed much since the advent of antipsychotic drug use nearly 30 years ago. Newer atypical antipsychotics show promise in improving target symptoms while causing fewer adverse effects.