Cognitive changes in post-stroke depression patients undergoing treatment with transcranial direct current stimulation (tDCS): an exploratory, ancillary analysis of a randomized, sham-controlled clinical trial

Objective: Post-stroke depression (PSD) affects approximately 40% of stroke survivors, with cognitive deficits being frequently observed. Transcranial Direct Current Stimulation (tDCS) has shown promise in improving cognitive performance in stroke patients. We explored the effects of tDCS on cognitive performance in PSD.

Methods: An exploratory analysis was conducted in 48 patients from a double-blinded, sham-controlled, randomized clinical trial that investigated the effects of tDCS for treating PSD. A neuropsychological battery was applied at baseline and endpoint. We assessed three key domains: (1) Stroop effect, measured by the Stroop test components (color naming, word-reading and word-color interference); (2) processing speed, assessed using the Trail Making Test and the Digit Symbol coding test; (3) executive function, evaluated with the Digit Span test and the Frontal Assessment Battery (FAB). A Linear mixed regression models were used to evaluate changes according to groups.

Results: We found that the active tDCS group worsened slightly, while the sham group improved in Executive Function for the adjusted models. Significant interactions were also found for FAB.

Conclusions: We found no consistent evidence that tDCS significantly improved the cognitive domains. The bidirectional association with cognition analysis suggest that tDCS effects may vary based on depression severity and task complexity.