Cognitive profiles in major depressive disorder: Comparing remitters and non-remitters to rTMS treatment

Major Depressive Disorder (MDD) is typically accompanied by cognitive impairment. Repetitive Transcranial Magnetic Stimulation (rTMS) treatment for MDD involves stimulation of the dorsolateral prefrontal cortex which plays an important role in cognition. This study aimed to identify differences in cognitive profiles between remitters and non-remitters to rTMS at baseline and across treatment. 25 patients with MDD performed cognitive tasks at baseline and after 6, 12 and 30 sessions of rTMS. At baseline, there was no difference in simple reaction time (RT) between groups, but remitters (n = 13) showed faster RTs than non-remitters (n = 12) in the Switch and No-Switch conditions of Task Switching. Across sessions, remitters showed a decrease in 3-Back omission errors and RTs to 3-Back, Stroop's Congruent and Incongruent, and Task Switching's Switch and No-Switch conditions, whereas non-remitters only showed improvements in Stroop Congruent and Incongruent RTs. Baseline and final scores on the Hamilton Depression Rating Scale were positively correlated with Switch and No-Switch RTs. This study demonstrates that eventual remitters to rTMS treatment for MDD perform better in cognitive tasks requiring shifting attention, and this difference is observable prior to the start of treatment. Remitters also show improvement in both their mood and cognitive performance.