Objective: To investigate whether repeated sessions of bilateral anodal tDCS can influence circulating antioxidant enzyme levels and fatigue severity in individuals with Parkinson’s disease.

Background: Oxidative stress is considered a key contributor to the pathophysiology of Parkinson’s disease (PD), promoting neuronal damage and disease progression. Antioxidant enzymes—including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)—play an important role in counteracting oxidative injury. Transcranial direct current stimulation (tDCS) has shown therapeutic potential in PD; however, its effects on systemic antioxidant activity remain unclear.

Method: This pilot randomized controlled trial enrolled thirteen individuals diagnosed with PD. Participants were allocated to either an active bilateral anodal tDCS group (n = 7) or a sham stimulation group (n = 6). The intervention consisted of ten stimulation sessions administered over two consecutive weeks, targeting bilateral prefrontal and motor cortical regions. Blood samples were obtained before and after the intervention to quantify serum concentrations of CAT, GSH-Px, and SOD. Clinical fatigue was evaluated using the modified fatigue scale, including physical, cognitive, and psychosocial domains.

Results: In tDCS active treatment group, analysis of serum biomarkers revealed a statistically significant increase in the serum levels of GSH-Px and CAT. Concurrent with these biochemical changes, participants in the anodal tDCS group demonstrated a significant clinical improvement, as evidenced by a reduction in their overall modified fatigue total score, indicating decreased fatigue severity.

While serum SOD levels did show an upward trend following active stimulation, and individual sub-scores of the modified fatigue scale also trended toward improvement, these changes did not reach the statistical significance. In the control groups (sham stimulation), no remarkable significant changes in the measured antioxidant enzyme levels or fatigue scores throughout the study period.

Conclusion: These preliminary findings suggest that neuromodulation may exert broader physiological effects beyond cortical excitability. Larger randomized trials are required to confirm these observations and clarify the relationship between neuromodulation and oxidative stress pathways in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/systemic-antioxidant-response-to-bilateral-anodal-transcranial-direct-current-stimulation-in-parkinsons-disease-findings-from-a-pilot-randomized-controlled-study/