title: Impairments in motor-cortical inhibitory networks across recent-onset and chronic schizophrenia: a cross-sectional TMS Study.
abstract: Transcranial magnetic stimulation is an established method to probe inhibitory and facilitatory networks within the human motor cortex. Reduced motor-cortical inhibition is a common finding in schizophrenia patients. Based on neuropathological findings, the reduced cortical inhibition in schizophrenia has been linked mainly to alterations in GABAergic neurotransmission. The aim of this study was to investigate the impact of disease state on intracortical inhibitory and facilitatory networks measured by TMS in schizophrenia. Cortical excitability was investigated in a pooled cross-sectional sample of recent-onset-schizophrenia (RO-SZ), chronically-ill schizophrenia patients (CH-SZ) and healthy controls (HC) using single- and paired-pulse TMS applied to the left primary motor cortex. The sample included 41 RO-SZ, 42 CH-SZ and 59 HC. Analyses were focused on resting motor threshold (RMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and cortical silent period (CSP). There was a significant difference regarding the mean CSP durations across our three study groups (p=0.002). Subgroup comparisons revealed a shorter CSP in HC compared to RO-SZ (p<0.001). Three group comparisons of SICI (p=0.098) and RMT (p=0.075) showed differences at a trend-level. An overall comparison between HC and all patients showed a significantly reduced SICI (p=0.031) and prolonged CSP (p=0.003) in schizophrenia patients. This is the largest and first cross-sectional investigation of various excitability parameters in schizophrenia patients. These findings indicate general alterations of cortical inhibition, with differences between recent-onset and chronically-ill schizophrenia patients.
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany. Electronic address: Wolfgang.Strube@med.uni-muenchen.de.
authors: Wolfgang
authors: W
authors: Strube
authors: Centre of Mental Health, Darmstadt-Dieburg Clinics, Darmstadt, Germany; Department of Psychiatry and Psychotherapy, University of Goettingen, Goettingen, Germany.
authors: Thomas
authors: T
authors: Wobrock
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Tilmann
authors: T
authors: Bunse
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Ullrich
authors: U
authors: Palm
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Frank
authors: F
authors: Padberg
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Berend
authors: B
authors: Malchow
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Peter
authors: P
authors: Falkai
authors: Department of Psychiatry and Psychotherapy, Ludwig Maximilian University, Munich, Germany.
authors: Alkomiet
authors: A
authors: Hasan
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology*; D012559:Schizophrenia / Q000473:pathology*; D018709:Statistics, Nonparametric; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Cortical silent period; GABA(A); Intracortical facilitation; Short-interval intracortical inhibition; Transcranial magnetic stimulation