A Double-Blind Randomized Sham Control Study to Assess the Effects of rTMS (Repetitive Transcranial Magnetic Stimulation) on Executive Functioning in Treatment Resistant Depression

SOURCE: International Journal of Pharmaceutical and Clinical Research. 14(5) (pp 328-340), 2022.


AUTHORS: Jagawat T.; Jagawat S.; Sandu M.; Sinha M.; Hazari N.

BACKGROUND: Up to fifteen percent of patients with Depression eventually present with Treatment Resistant Depression (TRD). Executive functions, in general, are a part of the cognitive process which includes fluency, working memory, set-shifting ability, set maintenance, planning, response inhibition, error detection, abstraction, strategizing and organization. Cognitive impairment / executive functions have found to be associated with depression. The Food and Drug Administration (FDA) has approved
Repetitive Transcranial Magnetic Stimulation (rTMS) for the treatment of both MDD (Major Depressive Disorder) and TRD in adolescent and adult populations. Aims and Objectives: To examine the effects of active and sham rTMS on executive functioning in patients of treatment resistant depression by comparing pre and post rTMS effects on mood symptoms, executive functioning for both groups (active and sham) and assessing the correlation between the effects on executive functioning and mood changes due to rTMS.

MATERIAL(S) AND METHOD(S): The study included 20 individuals (10 in each arm) of either gender, aged between 18-50years suffering from mild to moderate depression (assessed by HAM-D). The
executive functioning was assessed by using NIMHANS Neuropsychological Battery (Digit Symbol Substitution Test-DSST, Digit Sequencing Test-DST, Colour Trail making B test, and Stroop test), 10 sessions of either active HF-rTMS (10Hz) or sham rTMS (allocated by random sampling) were applied to the left DLPFC over two weeks.

RESULT(S): The mean age was found to be 42.62 years with 60 % males and 40 % females. On DSST Positive effects of rTMS were found for information processing speed in the active group compared to sham. On other tests, DST, CTB and Stroop test, the findings were not statistically significant. Significant positive correlation was present between HAM-D and Stroop tests scores in active group. The severity of depression reduced significantly due to rTMS treatment.

CONCLUSION(S): The important finding of this study is the decrease in time on DSST after treatment with rTMS in the active group showing improvement in visuomotor coordination, attention and information processing speed in patients with TRD.