Cortical inhibition in symptomatic and remitted mania compared to healthy subjects: A cross‐sectional study

Objectives Transcranial magnetic stimulation (TMS)‐derived cortical reactivity studies provide a unique opportunity to non‐invasively study gamma amino butyric acid (GABA)‐mediated inhibitory neurotransmission in bipolar disorder (BD). Earlier studies were conducted in smaller samples and on patients who were on medications that can potentially confound the results. We aimed to study short‐interval (SICI) and long‐interval intracortical inhibition (LICI) in medication‐naïve/free symptomatic (manic) BD patients (n=39), first episode mania (FEM) patients who had recently (≤6 months) remitted with treatment (remitted FEM; n = 28) and healthy subjects (HSs; n = 45). Methods Resting motor threshold (RMT), stimulation intensity to elicit a 1‐mV motor evoked potential (MEP) (SI1 mV), SICI and LICI were measured in three groups using single‐ and paired‐pulse TMS. Results Motor thresholds were higher in the manic BD and HS groups compared to the remitted FEM group (P