Abstract

Objectives: Geriatric depression is a significant public health burden and is challenging to treat. The current study aimed to examine the effectiveness of transcranial direct current stimulation (tDCS) as a nonpharmacologic intervention approach for depression in older adults.

Methods: We performed a systematic review of 24 studies across 13 countries including a total of 1,277 participants. Excluding six studies with incomplete data, we performed a metaanalysis of 18 randomized clinical trials (RCTs) involving 912 patients (502 active tDCS, 410 sham control tDCS).

Results: Results revealed a large effect size favouring active tDCS for depressive symptoms (SMD = -0.96, 95% CI -1.56 to -0.37), though with high heterogeneity (I² = 89%). Large effect sizes favouring active tDCS were demonstrated in clinician-administered depression measures (Hamilton Depression Rating Scale [HDRS], Montgomery-Åsberg Depression Rating Scale [MADRS], Cornell Scale for Depression in Dementia [CSDD]) as well as in self-report measures (Beck Depression Inventory [BDI], Zung Self-Rating Depression Scale [SDS]). Subgroup analyses showed a nonsignificant effect in studies focused solely on major depressive disorder (MDD) and a large, though preliminary, effect in studies limited to adults aged 65 and older.

Conclusions: These findings suggest that tDCS may be a promising nonpharmacological treatment option for depression in older adults, particularly in the context of comorbid conditions. However, further high-quality research specifically targeting this population is needed to validate its efficacy and optimize treatment protocols.