The trajectory of symptom change over the course of transcranial magnetic stimulation for major depressive disorder

Abstract Background The trajectory of improvement in depression severity during TMS needs specification and the trajectories of individual symptoms are largely unexplored. Methods PHQ-9 and QIDS-SR data were analyzed from 402 patients with MDD who received ≥36 TMS sessions and scored ≥10 on both instruments at baseline. Total severity and individual symptoms were assessed at baseline, after 5, 10, 20, and 30 sessions, and at the end-of-acute treatment. The extent to which TMS produced generalized improvement across symptoms or symptom-specific trajectories was evaluated. Results The findings were consistent across the PHQ-9 and QIDS-SR. The average trajectory in total scores reflected rapid improvement from baseline to the 5th session. The rate of improvement per session was markedly slower, but consistent, thereafter. Across 6 time points, the 9 symptom domains differed markedly in severity (ηP² ⁼ 31-37%). Similarly, there were large effects of time point across symptoms, reflecting generalized and progressive therapeutic change (ηP² ⁼ 44-48%). While statistically significant, only a small portion of the variance was due to differences among the items in their change over time (ηP² ⁼ 2-3%). TMS protocols and groups differing in clinical outcome did not differ in type or extent of symptom specificity. At the group level, the predominant pattern was a marked and progressive downward shift of the baseline profile of symptom severity throughout the course of TMS. Limitations The findings derived from two self-report instruments. Conclusions The trajectory of the antidepressant effect of TMS is nonlinear and generalized across depressive symptoms, showing limited symptom specificity.