Effects of Personality Styles on Clinical Response to Intermittent Theta Burst Stimulation for Depression

<b>Introduction:</b> Major depressive disorder (MDD) is a common and often treatment-resistant condition, with many patients showing only partial or minimal response to standard therapies. Repetitive transcranial magnetic stimulation (rTMS) is a well-established, non-invasive treatment for depression, though individual response varies considerably. While demographic and clinical predictors have been explored, the impact of personality styles on rTMS outcomes remains underinvestigated. Herein, we aimed to explore whether personality styles influence treatment response to rTMS. <b>Methods:</b> This retrospective study included 63 in- and outpatients with depressive episodes treated with intermittent theta-burst stimulation (iTBS) between September 2020 and December 2022. Patients were assessed before and after treatment using the 21-item Hamilton Depression Rating Scale (HAMD-21) and the self-reported Major Depression Inventory (MDI). Personality styles were evaluated using the German <i>Persönlichkeits-Stil-und-Störungs-Inventar</i> (PSSI), a dimensional measure of 14 personality styles. Statistical analyses included paired-samples <i>t</i>-tests to assess symptom change and linear regression models to examine whether personality styles predicted treatment outcomes. Effect sizes were reported as Cohen's <i>d</i>. <b>Results:</b> Patients showed a significant reduction in depressive symptoms following iTBS (HAMD-21: <i>t</i>(62) = 10.86, <i>p</i> < 0.001, <i>d</i> = 1.37. MDI: <i>t</i>(62) = 8.55, <i>p</i> < 0.001, <i>d</i> = 1.06). Stepwise regression for the MDI identified critical-negativistic (NT) and reserved-schizoid (SZ) styles as significant predictors, explaining approximately 16% of the variance (<i>R</i>² = 0.159, <i>p</i> = 0.007). When entered simultaneously in a regression model for the HAMD-21, these same traits also predicted symptom change, though the effect was smaller (<i>R</i>² = 0.108, <i>p</i> = 0.033). Higher scores of critical-negativistic (NT) style were associated with better improvement, whereas higher scores of reserved-schizoid (SZ) style were associated with less improvement. <b>Conclusions:</b> This study confirms the overall efficacy of rTMS in reducing depressive symptoms. While SZ and NT traits showed some predictive value for treatment response-particularly on self-reported outcomes-their influence was modest and inconsistent. Based on our findings, there is no reason why patients with depression and specific personality styles, or even comorbid personality disorders, should be denied rTMS treatment.