Effect of priming on adjunctive repetitive transcranial magnetic stimulation in treatment of late-life depression: protocol of a prospective randomized sham-controlled study.

Priming stimulation, which involves high-frequency repetitive transcranial magnetic stimulation (rTMS) followed by low-frequency, has been shown to enhance neural response and is one of the novel paradigms found beneficial in adult patients with depression and has not been studied in late-life depression (LLD). This study aims to compare the effect of adjunctive priming vis-a-vis no priming rTMS over right dorso-lateral prefrontal cortex (DLPFC), on treatment of LLD. This trial is registered in Clinical Trial Registry-India (CTRI) on www.ctri.nic.in. CTRI registration number: CTRI/2020/08/027230. Forty patients of LLD who are symptomatic after an adequate antidepressant trial will be randomized into 2 groups (active priming and sham priming rTMS); each receiving 10 sessions of rTMS over 2 weeks. Patients will remain blind to treatment allocation. Assessments will be done using Hamilton rating scale for depression, Geriatric Depression Scale, Hamilton rating scale for Anxiety, Somatic Symptom Severity Scale 8, Hindi Mental Status Examination, and Clinical Global Impression scale at baseline, week 1, 2, and 4. Side effect checklist will be applied after each session in both groups and at the end of 4 weeks. Data will be analyzed using statistical software Statistical Package for Social Sciences. Both the groups (active and sham groups) will be compared at the four given timepoints. Also, the baseline characteristics will be compared with the 3 follow-up points for any change. The findings of the study will give an insight to the possible role of priming to augment the effect of low-frequency rTMS in LLD.