Clinical use of the newer antipsychotic drugs.

The clinical use of clozapine and risperidone is reviewed. Traditional antipsychotic drugs are effective for treating the positive symptoms of schizophrenia but have little or no effect on the negative symptoms of this disease. Newer antipsychotic agents, such as clozapine and risperidone, are effective for treating both positive and negative symptoms in acutely ill and treatment-resistant patients. Clozapine and risperidone also have a lower incidence of extrapyramidal symptoms (EPS) than traditional antipsychotic drugs. Three hypotheses have been proposed to account for the newer agents' ability to relieve negative symptoms: (1) Improvement in negative symptoms may be linked to improvement in positive symptoms. (2) Negative symptoms may improve in the absence of the EPS often caused by traditional agents. (3) The newer antipsychotic agents may directly affect the neural circuits that trigger negative symptoms.