Basavaraju R, et al. - A cross-sectional study was conducted to investigate short-interval (SICI) and long-interval intracortical inhibition (LICI) in medication-naïve/free symptomatic (manic) bipolar disorder [BD] patients, first episode mania (FEM) patients who had recently (≤6 months) remitted with treatment. The study findings suggested that lower motor thresholds in remitted FEM perhaps reflected the effect of treatment, and could be studied as potential prognostic neuromarkers. Inverse findings for SICI (reduced) and LICI (increased) in BD show a possible differential involvement of the GABA_A and GABA_B subreceptor systems and these could be trait markers as they were impaired in both mania and euthymia.

Methods

• Using single- and paired-pulse transcranial magnetic stimulation (TMS), resting motor threshold (RMT), stimulation intensity to elicit a 1-mV motor evoked potential (MEP) (SI1 mV), SICI and LICI were measured in 3 groups.

Results

• The results of this study showed that motor thresholds were higher in the manic BD and HS groups compared to the remitted FEM group (P < .001).
• It was observed in the findings that SICI was lower (P = .026) but LICI was higher (P = .044) in the manic BD and remitted FEM groups compared to the HS group.