Role of the insula in rTMS response for depression


Author: Chien-Lin Wu1, Tsung-Hua Lu1, Wei Hung Chang2, Tzu-Yun Wang1, Huai-Hsuan Tseng3, Yen Kuang Yang1, Po See Chen4

Affiliation: <sup>1</sup> Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, Tainan, Taiwan.

<sup>2</sup> Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, Tainan, Taiwan; Department of Psychiatry, National Cheng Kung University Hospital, Dou-Liou Branch, Yunlin, Taiwan.

<sup>3</sup> Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, Tainan, Taiwan; Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

<sup>4</sup> Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, Tainan, Taiwan; Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Electronic address: chenps@mail.ncku.edu.tw.
Conference/Journal: J Affect Disord
Date published: 2024 Nov 12
Other:
  Pages: S0165-0327(24)01906-2   ,  Special Notes: doi: 10.1016/j.jad.2024.11.043.   ,  Word Count: 243  
    Background:

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).



Methods:

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.



Results:

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.



Limitations:

The small sample size of 25 participants is small.



Conclusion:

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.



Keywords: Bipolar disorder; Depression; Functional connectivity; Insula; Predictive biomarker; Repetitive transcranial magnetic stimulation.



PMID: 39542113 DOI: 10.1016/j.jad.2024.11.043