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Decreased Connectivity between Anterior Cingulate Cortex & Right Inferior Parietal Lobule May Predict Reduced Suicidal Ideation in TMS Patients

Poster Session D - Monday, March 31, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Hia Ghosh¹, Samadrita Chowdhury¹, Kevin Tristan Donaldson¹, Megan O'Connor¹, Olivia Newman¹, Shane Walsh¹, Tracy Barbour¹, Kristen Ellard¹, Lipeng Neng¹, Joan Camprodon¹; ¹Department of Psychiatry, Massachusetts General Hospital

Electroconvulsive therapy (ECT) reduces suicidal ideation by altering the brain’s functional connectivity. Our lab’s previous experiments have demonstrated that after ECT, increased functional connectivity between the anterior cingulate cortex (ACC) and the right inferior parietal lobule (IPL) is correlated with reduced suicidal ideation. We hypothesize that focally targeting the IPL with transcranial magnetic stimulation (TMS) will (1) increase ACC-IPL connectivity and (2) reduce suicidal ideation. Here, we present clinical and neuroimaging results from an open-label TMS study and from an ongoing mechanistic randomized controlled trial (RCT). We recruited 10 patients exhibiting moderate/high suicidality. Patients received accelerated intermittent theta-burst stimulation (iTBS) to the right IPL cluster of the Executive Control Network (ECN). We identified patient-specific right IPL coordinates using fMRI connectomics. Patients received 10 iTBS sessions over one day (18000 pulses; 120% of MT). We collected clinical and resting-state fMRI data before and after administering iTBS. The RCT utilizes the same neuromodulation protocol, but patients are randomly assigned either active or sham TMS. We observed a 48% reduction on the ideation subscale of the Columbia-Suicide Severity Rating Scale (t=2.71; p=0.024) and an increase in ACC-IPL functional connectivity (Cohen’s d=0.78), which supports our response biomarker hypotheses. Analyses for the ongoing RCT will be presented. We present an accelerated precision neuromodulation protocol that effectively engages the target biomarker (increase in ACC-IPL functional connectivity) and shows clinical efficacy (48% reduction in suicidal ideation) after a single day of treatment. Results from the larger RCT will further explore this hypothesis.

Topic Area: EMOTION & SOCIAL: Emotion-cognition interactions