Increased short-interval intracortical inhibition in un-medicated patients with schizophrenia

Abstract Background Schizophrenia is associated with changes in inhibitory and facilitatory brain networks which can be assessed by motor cortex excitability. Objective Here, we investigate differences between large cross-sectional samples of un-medicated and medicated patients with schizophrenia and healthy controls in single- and double-pulse transcranial magnetic stimulation parameters. Methods We measured right abductor digiti minimi muscle activity in 71 un-medicated, 43 medicated patients and 131 healthy controls. To exclude sample bias analyses were repeated with groups comparable for age and gender (un-medicated: n = 43; medicated: n = 38; controls: n = 49). Results Un-medicated patients showed increased short-interval intracortical inhibition (SICI) in contrast to medicated patients and healthy controls. No group differences were found for resting and active motor threshold, cortical silent period and intracortical facilitation. Conclusion Increases in SICI are in contrast to literature and highlight the necessity for large-scaled multi-centric studies with high methodological standards.