Trial finds no robust task-related benefit from rTMS in bipolar II disorder

Researchers randomized 96 euthymic patients with bipolar II disorder and subjective cognitive impairment in a 2 × 2 factorial trial of active or sham 10-Hz repetitive transcranial magnetic stimulation (rTMS), paired with a complex or simple cognitive task. Stimulation targeted the left inferior parietal lobule and was delivered in 10 sessions over five consecutive days. Outcomes included working-memory performance, perceived cognitive difficulties and resting-state functional connectivity. Eighty-three participants completed the trial; intention-to-treat analyses included all randomized participants.

No stimulation-by-task interaction survived correction for multiple comparisons. Some nominal interactions in working-memory error measures did not meet the corrected significance threshold. Model-estimated improvements across several working-memory outcomes were most consistent in the active-rTMS/simple-task group, but did not demonstrate superiority over the other groups. Perceived cognitive difficulties decreased in all four groups, without significant effects attributable to stimulation, task or their interaction. Exploratory imaging analyses found differing connectivity changes across conditions.

The exploratory findings do not show that adding complex cognitive engagement enhances the acute working-memory effects of rTMS in this population. The results do not establish a treatment benefit or support a change in practice; further studies are needed to assess task type and stimulation–task pairing. The source reports no longer-term outcomes.