Transcranial direct current stimulation plus cognitive training for cognitive symptoms in patients with post-acute sequelae of SARS-CoV-2 infection: A randomized, double-blind, sham-controlled trial.

Background: Post-acute sequelae of SARS-CoV-2 infection (PASC) is characterized by persistent cognitive deficits alongside anxiety and depression symptoms that adversely affect quality of life. Cognitive training (CT) programs and non-invasive neuromodulation, specifically transcranial direct current stimulation (tDCS), have each shown promise for alleviating similar deficits in non-clinical populations. However, their combined efficacy has not yet been evaluated in PASC patients. Therefore, this study aimed to determine whether the combination of CT and tDCS produces benefits for cognitive and mood-related symptoms in individuals with PASC.

Methods: We conducted a double-blind, randomized, sham-controlled clinical trial in adults aged 18-75 with confirmed SARS-CoV-2 infection within the past six months and persisting cognitive complaints. They were randomized to a 4-week in-person intervention of 20 weekday sessions of either active (2 mA anodal-left, cathodal-right prefrontal stimulation) or sham tDCS paired with an app-based CT program. Primary outcomes were six standardized neuropsychological tests assessing verbal memory, working memory, executive functioning, attention, and language, administered at baseline and immediately post-intervention. As secondary outcomes, we assessed changes in depression and anxiety symptoms over the treatment period.

Results: Sixty participants (mean age 43.8 ± 13.2 years, 71.7 % women) were randomized to active tDCS + CT or sham tDCS + CT groups, and 52 finished the trial. Compared to sham, tDCS + CT resulted in significantly greater improvement in tests evaluating inhibitory control (effect size [ES] = 0.07, 95 % CI 0 to 0.23, p = 0.046), processing speed (ES = 0.08, 95 % CI 0 to 0.25, p = 0.034), and divided attention (ES = 0.08, 95 % CI 0 to 0.24, p = 0.039), but not in tests evaluating other domains. Both groups improved similarly in depression and anxiety symptoms. Participant's and rater's active guess rates did not differ between groups (ps > 0.20).

Conclusion: An intervention with prefrontal targeted tDCS + CT in patients with PASC with cognitive complaints might be effective in improving attention, processing speed and inhibitory control, although further studies are warranted to prospectively confirm these findings.

Clinicaltrials: GOV: NCT05389592.