Subgenual cingulate connectivity as a treatment predictor during low-frequency right dorsolateral prefrontal rTMS: A concurrent TMS-fMRI study

• Published in: Brain stimulation Vol. 16; no. 4; pp. 1165 - 1172
• Main Authors: Tan, Vinh, Jeyachandra, Jerrold, Ge, Ruiyang, Dickie, Erin W, Gregory, Elizabeth, Vanderwal, Tamara, Vila-Rodriguez, Fidel, Hawco, Colin
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01-07-2023
• ISSN: 1935-861X; 1876-4754
• DOI: 10.1016/j.brs.2023.07.051

Repetitive transcranial magnetic stimulation (rTMS) to the dorsolateral prefrontal cortex (DLPFC) is effective in alleviating treatment-resistant depression (TRD). It has been proposed that regions within the left DLPFC that are anti-correlated with the right subgenual anterior cingulate cortex (sgACC) may represent optimal individualized target sites for high-frequency left rTMS (HFL).
This study aimed to explore the effects of low-frequency right rTMS (LFR) on left sgACC connectivity during concurrent TMS-fMRI.
34 TRD patients underwent an imaging session that included both a resting-state fMRI run (rs-fMRI
) and a run during which LFR was applied to the right DLPFC (TMS-fMRI). Participants subsequently completed four weeks of LFR treatment. The left sgACC functional connectivity was compared between the rs-fMRI
run and TMS-fMRI run. Personalized e-fields and a region-of-interest approach were used to calculate overlap of left sgACC functional connectivity at the TMS target and to assess for a relationship with treatment effects.
TMS-fMRI increased left sgACC functional connectivity to parietal regions within the ventral attention network; differences were not significantly associated with clinical improvements. Personalized e-fields were not significant in predicting treatment outcomes (p = 0.18).
This was the first study to examine left sgACC anti-correlation with the right DLPFC during an LFR rTMS protocol. In contrast to studies that targeted the left DLPFC, we did not find that higher anti-correlation was associated with clinical outcomes. Our results suggest that the antidepressant mechanism of action of LFR to the right DLPFC may be different than for HFL.