Feasibility of Combining tDCS with Exercise for Increasing Physical Activity in People with Depression

Ana Abrantes^1,2*Julia Browne^2,3Mascha van 't Wout^1,2Linda Carpenter^1,2Michael D Stein⁴Lisa A Uebelacker^1,2Daniel Audet¹Julie A Desaulniers¹Sarah Garnaat^5,6

• ¹Butler Hospital, Providence, United States
• ²Warren Alpert Medical School, Brown University, Providence, Rhode Island, United States
• ³Providence VA Medical Center, United States Department of Veterans Affairs, Providence, Rhode Island, United States
• ⁴School of Public Health, Boston University, Boston, Massachusetts, United States
• ⁵Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States
• ⁶Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, United States

Physical inactivity and depression are significant public health concerns, often co-occurring and exacerbating one another. Transcranial direct current stimulation (tDCS) has shown promise in enhancing cognitive and affective processes, potentially improving exercise adherence and outcomes in individuals with depressive symptoms. This study aimed to evaluate the feasibility and preliminary within group effects of combining tDCS with an aerobic exercise (AE) intervention to increase physical activity in individuals with elevated depressive symptoms. A pilot randomized controlled trial (RCT) was conducted with 51 participants exhibiting low physical activity levels and elevated depressive symptoms. Participants were randomized to receive either active tDCS (n=25) targeting the left dorsolateral prefrontal cortex (DLPFC) or sham tDCS (n=26), followed by supervised AE sessions three times per week for eight weeks. Physical activity was measured using accelerometers, and secondary outcomes included cardiorespiratory fitness, depressive symptoms, and affect.Feasibility metrics indicated moderate adherence rates to sessions, good follow-up rates, and successful blinding as belief about receiving active stimulation was comparable across conditions.Within the active tDCS group, small-to-medium effect sizes were observed for increases in accelerometer-derived daily steps (d = 0.36) and MVPA (d = 0.34) at end of treatment. Both the active tDCS and sham groups demonstrated large within-group improvements in cardiorespiratory fitness (d = 0.99 for active, d = 1.18 for sham) and self-reported MVPA (active d = 0.78, sham d = 0.90). Similarly, large reductions in depressive symptoms (active d = -1.00, sham d = -0.88) were observed within both groups. The combination of tDCS and AE appears feasible and shows preliminary potential for positively influencing daily step counts in individuals with depressive symptoms. The results support further investigation into tDCS as an adjunctive treatment to enhance exercise outcomes in this population.