A Pilot Study of Transcranial Magnetic Stimulation Effects on Cognitive Distortions and Metacognition in Treatment-resistant Major Depression

Background: Transcranial Magnetic Stimulation (TMS) has well-established effects on the hallmark symptoms of depression (e.g., DSM symptom criteria), yet it remains unknown whether other clinical phenomena are responsive, such as cognitive distortions and metacognitive disturbances that are central to psychological models of depression. Methods: The author assessed cognitive distortions and metacognition with two validated self-report measures (Cognitive Distortions Questionnaire, CDQ, and Metacognition Questionnaire, MCQ-30, respectively) in the first and final weeks of naturalistic TMS treatment in a continuous series of 20 outpatients with treatment-resistant major depression, along with two weekly self-report symptom measures (PHQ9 and IDS-30-SR). Results: Analysis of covariance (with Age, Gender and pre-treatment PHQ9 scores as covariates) showed significant effects of Time (p < 0.001), Scale (p < 0.001) and the Time-by-Scale interaction (p = 0.027). In post-hoc one-tailed paired t tests, each scale showed a significant decrease in mean score from First week to Final week. Clinical Responders (n = 10; defined as PHQ9 decrease ≥ 50%), compared to others (n = 10), showed numerically greater mean reductions in CDQ (36% vs. 18%; Cohen’s d = 0.62) and MCQ-30 (8% vs. 2%; d = 0.65). CDQ reductions were moderately correlated with PHQ9 reductions (r = 0.44) and IDS-30-SR reductions (r = 0.45); MCQ-30 reductions were minimally correlated with PHQ9 reductions (r = 0.09) and IDS-30-SR reductions (r = 0.22). Lower baseline CDQ scores were predictive of stronger outcomes on the PHQ9 (r = .62). Conclusion: TMS may remediate higher-order psychological processes such as cognitive distortions and metacognition in TRD, on a relatively short timescale and somewhat independent of symptom relief. The CDQ in particular may have unique, complementary and sensitive utility in monitoring TMS treatment effects in TRD.