Effect of Repetitive Transcranial Magnetic Stimulation on Neurocognitive Functions in Moderate and Severe Depression: A Longitudinal Study

Objective: We aimed to investigate the effects of transcranial magnetic stimulation (TMS) on depressive symptoms and neurocognitive functions during treatment and follow-up. Methods: A total of 65 patients diagnosed with major depressive disorder, with a >16 scores in Hamilton Depression Rating Scale (Ham-D) and a >18 scores in Beck Depression Inventory (BDI), participated in the study. The Ham-D, BDI, Beck Anxiety Inventory (BAI), Trail Making Tests A and B, Stroop Colour and Word Test, Number Sequence Test, Öktem Verbal Memory Processes Test, and Verbal Fluency Test were administered at baseline, 1st-, and 3rd-month for both treatment and control groups. Results: A total of 65 patients were enrolled in the study, of whom 25 in the TMS group and 26 in the non-TMS group completed the follow-up. At the first month, 73.5% of patients in the TMS group showed a full treatment response, compared to 29.03% in the non-TMS group (p=0.001). At the third month, the treatment response rate decreased to 40% in the TMS group, whereas it was 42.3% in the non-TMS group, and the significant difference between the groups disappeared (p=0.918). In terms of cognitive functions, no significant changes were observed in either group at the first- and third-month follow-ups compared to baseline. Conclusion: TMS had a strong acute antidepressant effect; however, this effect diminished over time during the follow-up period. Although partial improvement was observed in cognitive functions, this improvement did not reach statistical significance.