The Effect of Transcranial Direct Current Stimulation (tDCS) on Depression Symptoms in Patients with Chronic Low Back Pain: A Systematic Review and Meta-Analysis

Objective: Chronic low back pain (CLBP) often co-occurs with depression, significantly impacting quality of life. Transcranial direct current stimulation (tDCS) has shown potential in managing both conditions, but its effectiveness in addressing psychological symptoms in CLBP patients remains unclear. To investigate the effects of tDCS on pain intensity and depressive symptoms in patients with chronic low back pain through systematic review and meta-analysis. Design: A systematic review and meta-analysis. Methods: A systematic search was conducted in CINAHL, Embase, MEDLINE, and Web of Science databases for randomized controlled trials (RCTs) published within the last 10years. Studies comparing active tDCS (alone or combined with conventional therapy) to sham tDCS in adults with CLBP were included. The primary outcomes were pain intensity and depression scores. Two independent reviewers assessed methodological quality using the Cochrane risk of bias tool. Random-effects meta-analyses were performed using RevMan 5.4. Results: Four RCTs involving 273 participants met the inclusion criteria. Meta-analysis showed no significant difference between active and sham tDCS for either pain intensity (SMD=-0.08; 95% CI=-0.50 to 0.34; p=0.71; I2=41%) or depressive symptoms (SMD=-0.15; 95% CI=-0.43 to 0.13; p=0.29; I2=0%). The overall quality of evidence was moderate, with low risk of bias across most domains. Conclusions: Current evidence does not support the effectiveness of tDCS in reducing pain intensity or depressive symptoms in CLBP patients. Future research should focus on standardized protocols and well-defined subgroups of CLBP patients with psychological comorbidities.