Subgenual cingulate theta activity predicts treatment response of repetitive transcranial magnetic stimulation in participants with vascular depression

Abstract

Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression. Increased metabolism in the anterior cingulate cortex (ACC) is a known predictor for antidepressant response. The authors assessed whether increased theta power within the ACC predicts rTMS response in participants with vascular depression. Sixty-five participants were randomized to active or sham rTMS. Outcome was assessed using the Hamilton Depression Rating Scale. Electroencephalography was obtained, and comparisons were made among each group with a normative database using low-resolution electromagnetic tomography. Results suggest that vascular depression participants respond well to rTMS and that increased low-theta power in the subgenual ACC predicts response to rTMS.

Figure 1

Flow Chart of Inclusion of Subjects into Active Versus Sham rTMS Groups

Figure 2. Z Scores of Lw-theta Pwer (4–5 Hz) in Pre-rTMS Responders versus Non-Responders with LORETA

(A) A whole brain analysis of pretreatment data for rTMS responders (n=14) normalized against a standardized age-adjusted normative database within NeuroGuide (i.e., Z scores) revealed significantly higher than normal Z scores in low-theta power (4–5 Hz) within the subgenual ACC (BA25). Only the BA25 voxels which had significantly increased low-theta power are shown in red color. (B) A similar analysis of pretreatment data for rTMS non-responders (n=18) revealed no higher or lower theta activity or statistically significant Z scores before rTMS.

Figure 3. Pretreatment Low Theta Power in the Subgenual ACC

Scatterplot showing pretreatment low-theta power in the subgenual ACC among the three groups revealed a significant difference in low-theta power between those who responded versus those who did not respond to active rTMS prior to rTMS (F=4.18, df=1, 30, p=0.04; comparison between the active two groups).

Figure 4. Correlation Between Subgenual ACC Low Theta Power Percent Change and HAM-D Percent Change

Scatterplot demonstrating that there is a significant and positiv ve correlation between % changes in low-theta power in the subgenual ACC and total HAM-D among participants with active rTMS (Spearman ρ=0.45, p<0.01). HAM-D=Hamilton Depression Rating Scale; ACC=anterior cingulate cortex