Excitability of the motor cortex in schizophrenia following typical and atypical antipsychotics: two serial case...

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.