Transcranial Direct Current Stimulation (tDCS) for Post-COVID Fatigue: A Randomized, Double-Blind, Controlled Pilot Study

Background: Fatigue is one of the most frequent and disabling symptoms of post-COVID syndrome.ObjectiveTo assess the effects of transcranial direct current stimulation (tDCS) on fatigue severity in a group of patients with post-COVID syndrome and long-lasting fatigue.Methods: Double-blind, parallel-group, sham-controlled study to evaluate the short-term effects of anodal tDCS (2 mA, 20 min/day) on the left prefrontal dorsolateral cortex. The Modified Fatigue Impact Scale score was used as the primary endpoint. Secondary endpoints included cognition (Stroop test), depressive symptoms (Beck Depression Inventory), and quality of life (EuroQol-5D). Patients received eight sessions of tDCS and were evaluated at baseline, immediately after the last session, and one month later.Results: Forty-seven patients were enrolled (23 in the active treatment group and 24 in the sham treatment group); mean age was 45.66 ± 9.49 years, and 37 (78.72%) were women. The mean progression time since acute infection was 20.68 ± 6.34 months. Active tDCS was associated with a statistically significant improvement in physical fatigue at the end of treatment and at one month as compared with sham stimulation. No significant effect was detected for cognitive fatigue. In terms of secondary outcomes, active tDCS was associated with an improvement in depressive symptoms at the end of treatment. The treatment had no effects on quality of life. All the adverse events reported were mild and transient, with no differences between the active stimulation and sham stimulation groups.Conclusions: Our results suggest that tDCS on the dorsolateral prefrontal cortex may improve physical fatigue. Further studies are needed to confirm these findings and optimize stimulation protocols.