Safety and Efficacy of Continuous Theta Burst "Intensive" Posterior Parietal Cortex Stimulation in Generalized Anxiety Disorder: A Randomized Double-Blind Sham-Controlled Trial.

Objectives: Citing nonresponse to conventional treatments, neuromodulation based treatments are needed in generalized anxiety disorder (GAD). Data regarding continuous TBS (cTBS) in GAD has been anecdotal. Citing right posterior parietal cortex (PPC) hyperconnectivity in GAD, we aimed to study the effect of intensive cTBS targeting PPC in a randomized rater-blinded placebo-control design.

Material and methods: Forty-four patients age range 18-59 years (baseline Hamilton Anxiety Rating Scale [HAM-A] score >18 or Clinical Global Impression Severity [CGI-S] score of ≥4) were randomly allocated to active cTBS (n = 22) and sham cTBS (n = 22) groups using block randomization method. They received 10 cTBS sessions, 2 sessions per day (total of 1200 pulses) for 5 days in a week at 80% motor threshold. HAM-A, World Health Organization's abbreviated quality of life assessment (WHOQOL-BREF), and CGI-S were assessed at baseline, after the last session, and at 2 weeks after cTBS with gender as covariate. Intention-to-treat analysis was conducted and missing values were replaced using the last observation carried forward method.

Results: On repeated measures analysis of variance, a significant between-group time effect for HAM-A (F = 29.6; P = 0.001; ηp2 = 0.420), CGI-S (F = 24.7; P = 0.001; ηp2 = 0.376), and WHOQOL-BREF (F = 29.6; P = 0.001; ηp2 = 0.420). Logs of odds of response of >50% improvement in HAM-A between active and sham groups is 3.27 (95% CI [0.345, 6.20]). No major side effects were reported and none discontinued the trial because of side effects.

Conclusions: Our trial concludes that cTBS of posterior parietal cortex is safe, well-tolerated, and effective in GAD.