Effects of sMRI-guided rTMS on brain function and structure in major depressive disorder

Major depressive disorder (MDD) is a leading cause of disability worldwide. Repetitive transcranial magnetic stimulation (rTMS) guided by structural magnetic resonance imaging (sMRI) has emerged as a promising non-invasive treatment. However, the neural mechanisms underlying its efficacy remain unclear.

Thirty-three MDD patients and forty-two healthy controls underwent resting-state functional MRI and structural MRI scans. Among the MDD patients, thirty were rescanned after receiving 10 sessions of sMRI-guided rTMS over 2 weeks. Amplitude of low-frequency fluctuations (ALFF), resting-state functional connectivity (rsFC), and gray matter volume (GMV) were analyzed before and after treatment. The correlations of brain imaging changes after rTMS with clinical outcomes were calculated.

At baseline, compared to the healthy controls, MDD patients exhibited decreased ALFF in the right angular gyrus, right superior frontal gyrus (SFG), and left precuneus, as well as increased ALFF in the left inferior parietal lobe (IPL) and right middle temporal gyrus (MTG). Following rTMS treatment, ALFF in the right angular gyrus and right SFG increased, while rsFC between the right angular gyrus and left MTG decreased. No significant changes in GMV were observed post-treatment. These neuroimaging changes were not significantly correlated with clinical efficacy.

These findings indicate that sMRI-guided rTMS may induce restoration of local functional activity in the angular gyrus and SFG, as well as normalization of aberrant functional connectivity within the default mode network (DMN) in MDD patients. However, correlation analyses indicate these changes may not necessarily represent the neuroimaging mechanisms underlying sMRI-guided rTMS treatment effects.