Home-delivered transcranial direct current stimulation with or without cognitive training in mild dementia due to Alzheimer's disease

BackgroundTranscranial direct current stimulation (tDCS) and cognitive training are non-pharmacological interventions for cognitive impairment in Alzheimer's disease (AD), but evidence on combined protocols in mild dementia remains limited.ObjectiveTo evaluate home-delivered active tDCS combined with cognitive training and active tDCS alone versus sham tDCS in mild dementia due to AD, and explore whether the combined intervention showed changes across a broader range of cognitive outcomes.MethodsForty participants with mild dementia due to AD and evidence of amyloid-β pathology were randomized to tDCS combined with cognitive training (n = 14), active tDCS alone (n = 14), or sham tDCS (n = 12). The 10-day intervention was delivered at participants' homes by trained study personnel. Cognitive outcomes were assessed at baseline, post-intervention, and 1-month follow-up using linear mixed-effects models.ResultsSignificant Group × Time interactions were observed for the primary cognitive outcome, Mini-Mental State Examination (MMSE), and for all secondary cognitive outcomes except Backward Digit Span. Both active conditions showed greater change from baseline than sham tDCS in MMSE, Memory Alteration Test, verbal learning, total verbal recall, and delayed recall. The combined condition also showed greater change than sham tDCS in initial immediate recall and Forward Digit Span. No significant differences were observed between the two active conditions.ConclusionsActive tDCS, with or without cognitive training, was associated with more favorable short-term cognitive change than sham stimulation. The combined condition differed from sham across more outcomes, but not from active tDCS alone; therefore, this exploratory pattern does not establish a broader benefit of the combined intervention.