EXCITABILITY OF THE MOTOR CORTEX IN SCHIZOPHRENIA FOLLOWING TYPICAL AND ATYPICAL ANTIPSYCHOTICS: TWO SERIAL CASE REPORTS

SUMMARY A previous electrophysiological investigation of schizophrenia using transcranial magnetic stimulation has shown altered corticospinal inhibition in medicated patients compared with drug‐naive patients. Based on this work, we have carried out the first serial electrophysiological case studies of the human corticospinal system in schizophrenia in which a typical antipsychotic was compared with an atypical antipsychotic. We used transcranial magnetic stimulation‐based techniques to study the time course of drug action in two antipsychotic drug‐naive patients with schizophrenia; one patient treated with a typical antipsychotic (haloperidol) and the other with an atypical antipsychotic (risperidone). The typical antipsychotic was associated with an increase in corticospinal excitability which we found to occur 4–5 weeks after beginning medication. In contrast, the atypical antipsychotic was associated with a decrease in corticospinal excitability, occurring 3–4 weeks after starting pharmacotherapy. We conclude that these opposite neurophysiological effects are related to the relative dopaminergic and serotonergic actions of the two classes of drug. (Int J Clin Pract 2003; 57(9): 831–833)