Are neuroticism and extraversion associated with the antidepressant effects of repetitive transcranial magnetic stimulation (rTMS)? An exploratory 4-week trial.

Several randomized, controlled trials have found high frequency repetitive transcranial magnetic stimulation (HF-rTMS) to be effective for treating major depressive disorder (MDD), but its antidepressant mechanisms have yet to be firmly understood. In this context, pre-treatment personality traits and subsequent changes in personality concomitant to treatment may be relevant for our understanding of these mechanisms. To investigate this issue we conducted a naturalistic trial in which 14 subjects with moderate to severe depression were treated with daily HF-rTMS over the left dorsolateral prefrontal cortex for 4 weeks. Objective depressive symptoms (as assessed by the HAM-D(21)) and the major personality dimensions of neuroticism and extraversion were measured pre-post HF-rTMS. Pre-rTMS levels of extraversion predicted subsequent decrease in depressive symptoms. Also, HF-rTMS treatment resulted in a decrease in neuroticism scores, and this relative decrease was associated with the relative decrease in depression. Our results suggest that HF-rTMS may positively affect the personality dimension of neuroticism. Also, pre-treatment levels of extraversion may predict the subsequent antidepressant response to HF-rTMS. However, further studies with larger samples and controlled designs are needed to better clarify these preliminary findings.