(Open access funding provided by Semmelweis University)
Cortical excitation-inhibition (E/I) imbalance is a potential model for the pathophysiology
of schizophrenia. Previous research using transcranial magnetic stimulation (TMS)
and electromyography (EMG) has suggested inhibitory deficits in schizophrenia. In
this meta-analysis we assessed the reliability and clinical potential of TMS-EMG paradigms
in schizophrenia following the methodological recommendations of the PRISMA guideline
and the Cochrane Handbook. The search was conducted in three databases in November
2022. Included articles reported Short-Interval Intracortical Inhibition (SICI), Intracortical
Facilitation (ICF), Long-Interval Intracortical Inhibition (LICI) and Cortical Silent
Period (CSP) in patients with schizophrenia and healthy controls. Meta-analyses were
conducted using a random-effects model. Subgroup analysis and meta-regressions were
used to assess heterogeneity. Results of 36 studies revealed a robust inhibitory deficit
in schizophrenia with a significant decrease in SICI (Cohen’s d: 0.62). A trend-level
association was found between SICI and antipsychotic medication. Our findings support
the E/I imbalance hypothesis in schizophrenia and suggest that SICI may be a potential
pathophysiological characteristic of the disorder.
