Neuropathic pain is a common disorder that may cause physical impairment and has been associated with anxiety and depression. The Transcranial Direct Current Stimulation (tDCS) may assist in managing populations with chronic symptoms. However, findings in the literature remain conflicting, with prior studies reporting small effect sizes and factors that may influence tDCS efficacy.

To evaluate the effects of tDCS on anxiety and depression in patients with chronic neuropathic pain.

A literature search was conducted in the MEDLINE, CINAHL, EMBASE, and CENTRAL databases in February 2024. Included studies were controlled clinical trials involving patients with chronic neuropathic pain undergoing tDCS. The meta-analysis was calculated using the Standardized Mean Difference (SMD) with a 95% confidence interval (CI) and the level of evidence was assessed with GRADE approach.

The search retrieved 1,729 articles. After screening, 9 studies were included and compared the effects of active tDCS versus sham tDCS on depression, with a combined sample of 256 participants, and 8 studies that investigated effects on anxiety, with a total of 216 participants. All studies applied anodal current to the stimulation target. The predominant stimulation site was the Primary Motor Cortex (M1), with current intensity ranging from 1 mA to 2 mA, 5–14 sessions, and session duration of 20–30 minutes each. Low-quality evidence indicated that active tDCS was not superior to sham tDCS in improving depression (SMD = -0.24; 95% CI [-0.55, 0.07]; P = 0.13), with low heterogeneity (I² = 32%, P = 0.16). Low-quality evidence showed no superiority of active tDCS over sham tDCS in reducing anxiety (SMD = -0.23; 95% CI [-0.63, 0.17]; P = 0.26), with moderate heterogeneity (I² = 50%, P = 0.05).

The meta-analysis indicated that tDCS was not superior to sham interventions for improving anxiety or depression in individuals with neuropathic pain.

tDCS should not be used for treating anxiety and depression in patients with chronic pain.