Role of the insula in rTMS response for depression.

The insula has a significant impact on interoception and depression. This study aims to explore the role of the insula in mediating treatment responses to high-frequency repetitive transcranial magnetic stimulation (rTMS) targeting the left dorsolateral prefrontal cortex (DLPFC). Twenty-five patients with either bipolar disorder (BD, n = 15) or major depressive disorder (MDD, n = 10) were recruited. All subjects were aged between 20 and 70, with a minimum score of 18 on the 24-item Hamilton Rating Scale for Depression (HDRS-24). Each patient received 12 sessions of rTMS treatment using a figure-eight-shaped coil at 10 Hz high-frequency stimulation intensity, targeted to the left DLPFC. Resting-state functional magnetic resonance imaging was conducted before and after the rTMS treatment to assess changes in insula-seeded functional connectivity. Both BD and MDD patients experienced significant reductions in depressive symptoms following rTMS therapy. The respective response rates at weeks 4, 8 and 12 were 64.0 %, 64.0 % and 68.0 % and remission rates were 40.0 %, 36.0 % and 44.0 %. Decreases in functional connectivity between the right anterior insula and right calcarine were significantly larger in the remitters than in the non-remitters (p = 0.013). Additionally, a higher baseline functional connectivity between the right anterior insula and right superior temporal gyrus correlated with better treatment outcome. The small sample size of 25 participants is small. Our findings highlight the potential role of the insula in depression and suggest that insula-seeded functional connectivity could serve as a predictive biomarker for rTMS efficacy. • rTMS reduces depressive symptoms in BD and MDD patients for at least 12 weeks. • Decreases in insula and calcarine connectivity correlate with symptom improvement after rTMS. • Higher baseline connectivity of insula and superior temporal gyrus predicts better rTMS outcome. • Insula connectivity can serve as a predictive biomarker to optimize rTMS treatment. [ABSTRACT FROM AUTHOR]