25. Low frequency rTMS effect over the right dorsolateral prefrontal cortex in treatment-resistant depression: Effects on affective symptoms, cognitive function and P300 components

Repetitive transcranic magnetic stimulations (rTMS) is an effective tool for treatment-resistant depression (TRD). Only a few studies investigated the response predictors to rTMS and its effects on cognitive functions in depressed patients. Our aims were: (1) confirm the rTMS antidepressant and neurocognitive effects in TRD; (2) evaluate the possible role of the Event-Related Potential P300 as response predictor. Methods: Thirteen patients (aged 41–76) with unipolar or bipolar TDR, received low-frequency rTMS over the right DLPFC in a 3-week trial (15 daily session, 1800 stimuli per session). We assessed rTMS effects on depressive and anxiety symptoms, neurocognitive functions and the P300. Six patients were considered as remitters. The Rey Auditory Verbal Learning Test improved independently from the antidepressant rTMS effect. The latency of P300 was significantly increased both at the baseline and at the end of the rTMS treatment. However considering the acute effect of rTMS, only at the day 15 rTMS determined a significant increase of P300 latency as in healthy subjects. Our data confirm antidepressant effectiveness of rTMS for TDR. Neurocognitive effects were limited to Verbal Learning. P300 seems no to be a response predictor but eventually a Neurophysiological marker of efficacy.