Structural alterations after repetitive transcranial magnetic stimulation in depression and the link to neurotransmitter profiles

Background

Repetitive Transcranial Magnetic Stimulation (rTMS) is widely used to treat depression, showing good efficacy and tolerability. However, the neurobiological mechanisms of its antidepressant effects remain unclear. This study explores the potential impact of rTMS on brain structure in depressed patients and its link to neurotransmitter systems.

Methods

Thirty-six MDD patients were randomized to receive 5 times per week for 3 weeks of active or sham rTMS targeting the dorsolateral prefrontal cortex (DLPFC) within a double-blind, sham-controlled trial. The Hamilton Depression Rating Scale-17 items (HAMD-17) was used to assess depressive symptoms at baseline and the end of 1 W, 2 W and 3 W after treatment. We analyzed the differences in efficacy between the two groups of patients at different time points, and the grey matter changes of the brain before and after treatment in both groups. In addition, we analyzed the spatial correlations between abnormal grey matter and the neurotransmitter receptors and transporters map.

Results

Both the active and sham groups showed significant improvement in depression and anxiety symptoms following rTMS treatment, with the Active group demonstrating greater improvement. Additionally, the Active group exhibited increased grey matter volume in regions associated with the frontal-limbic network, and these changes were significantly correlated with the spatial distribution of D1 receptors.

Conclusion

This study suggests that rTMS targeting the left DLPFC produces antidepressant effects by enhancing structural plasticity in the frontal-limbic network, and that dopamine system modulation may underlie rTMS therapeutic effects. These findings provide insight into the neurobiological basis of rTMS for depression treatment.