Affective state-dependent effects of prefrontal rTMS on the cognitive control of negative stimuli in healthy and depressed individuals

INTRODUCTION: High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) targeting the left dorsolateral prefrontal cortex (lDLPFC) is an established, clinically effective treatment for major depressive disorder (MDD). However, evidence of the cognitive effects of lDLPFC HF-rTMS, especially those cognitive functions affected by MDD, is mixed. METHODS: We here assessed the cognitive effects of a single, offline, 10Hz rTMS session on task performance in an emotional faces N-back (EFNBACK) task, in both healthy and depressed individuals. We measured response times, accuracy, and sensitivity, in a sham-controlled, pre-post design. Importantly, using the Beck Depression Inventory (BDI-II), we assessed whether the cognitive effects of the stimulation are state-dependent on trait-state depression. RESULTS: We found lDLPFC HF-rTMS enhanced cognitive control over angry distractors. More importantly, these cognitive control effects were state-dependent on trait-state depression. HF-rTMS produced distinct performance changes dependent on baseline BDI-II scores. As a function of BDI-II scores, we observed either increased or decreased response times on the task. Further, we observed improved accuracy and sensitivity only on angry distractor trials as BDI-II scores increased, as a consequence of lDLPFC stimulation. CONCLUSION: These results underscore the role of HF-rTMS in enhancing executive control over negative emotional information by modulating lDLPFC, with effects varying according to depression state at the moment of the treatment session. HF-rTMS thus not only enhances inhibitory control over emotional stimuli but also exhibits such cognitive effects contingent on depressive state, contributing to our understanding of the state-dependence of therapeutic rTMS.