Cortical excitability in neuroleptic-naive first-episode schizophrenic patients

Transcranial magnetic stimulation (TMS) provides an intriguing in vivo method to investigate motor cortex excitability in men. This offers new insights into the neurophysiological basis of neuropsychiatric diseases. Earlier TMS studies in patients with schizophrenia revealed inconsistent results, probably due to major confounding variables like state of medication and stage of illness. To control for these effects, we studied two TMS paradigms in 21 drug-naive first-episode schizophrenic patients and 21 age- and sex-matched healthy controls. The patient group demonstrated a significant lower resting motor threshold as compared with healthy controls, whereas TMS paradigms of intracortical inhibition and intracortical facilitation failed to show significant differences between patients and controls. Our findings suggest that drug-induced and naturally occuring psychosis may share a common pathway, which may base on dysfunctional glutamatergic mechanisms.