Motor side effects of atypical antipsychotic drugs

Author(s): Victoria Chang and Joseph H Friedman

The development of clozapine was thought to herald a new era of antipsychotic drug treatment by virtue of increased effi cacy and fewer motor side effects. However, its non-motor side effects undermined its utility. We will argue that with the exception of quetiapine and clozapine, the other members of the ‘atypical antipsychotics’ have signifi cant motor side effects, and that these side effects differ from drug to drug. All of the other compounds cause parkinsonism and worsen motor function in people with parkinsonian syndromes. Some are more likely than others to cause either acute dystonic reactions or akathisia. Only risperidone has so far been clearly linked as a cause of tardive dyskinesia when used long-term in neuroleptic-naive patients, but this lack of association may be due only to limitations in data collection. All of the atypical antipsychotics, including quetiapine and clozapine, have been convincingly reported to cause neuroleptic malignant syndrome.