Feasibility and pilot efficacy of self-applied home-based cognitive training and brain stimulation

ObjectiveTo assess whether home-based, self-applied cognitive training combined with tDCS in older adults is feasible (primary), acceptable, and effective (secondary). DesignMonocentric, double-blind, randomized (1:1), controlled trial conducted from May 2021 to July 2023, involving six at-home sessions and pre-, post- and follow-up assessments in the laboratory. SettingUniversity Medicine Greifswald and participants homes. ParticipantsThirty older adults (60-80 years), randomized to anodal or sham tDCS group (n = 15 each). InterventionsSix sessions at home over the course of two weeks (three per week) with training of letter updating and concurrent self-applied tDCS (1.5 mA, 20 min/30 s). Participants were thoroughly trained in self-application of the stimulation and handling of the material. Main outcomes measuresThe primary outcome was feasibility, operationalized by successfully performed interventional sessions per participant. Four or more out of six sessions successfully performed in at least 60% of all participants were defined for the trial to be deemed feasible. Secondary outcomes included: acceptability assessed via questionnaire and cognitive performance on training and transfer tasks. Results29 participants successfully completed four or more out of six intervention sessions (96.7%, 95%-CI: [81.9, 100.0]), confirming the feasibility of the intervention (primary outcome). Overall satisfaction with the intervention and mean feasibility rating was high (93%, 95%-CI: [77.6 to 99.2]). Training (letter updating) task performance was superior in the target compared to the control group ({beta} = 3.5, 95%-CI: [0.5 to 6.6], p = 0.037). There was no substantial difference in the transfer (N-back) task ({beta} = -5.1, 95%-CI: [-14.6 to 4.5], p = 0.23). ConclusionsSelf-administered, home-based combination of cognitive training and tDCS is feasible and acceptable in older adults. Pre-defined secondary outcomes indicate superior cognitive enhancement of the trained function in the active stimulation group. Our study indicates that a Phase III trial is now warranted. Trial registrationProspectively registered (clinicalTrials.gov, NCT04817124). Summary boxesO_ST_ABSWhat is known about this topicC_ST_ABSO_LIEffective interventions for age-related cognitive decline are not available and constitute a major unmet medical need C_LIO_LICombining cognitive training with transcranial direct current stimulation (tDCS) is a safe, low-cost, and potentially effective approach for treating age-related cognitive decline, but currently used laboratory-based interventions over extended periods are time-consuming and laborious for both clinicians and patients, and thus not feasible in routine care. C_LIO_LIFeasibility, acceptability and efficacy of home-based, self-administered tDCS combined with cognitive training in older adults still need to be determined. C_LI What this study addsO_LIThis study demonstrates that home-based, self-administered tDCS combined with cognitive training is feasible, acceptable and potentially effective for enhancing cognitive functions in older adults. C_LIO_LIOur findings pave the way for a subsequent Phase III clinical trial to provide high-level evidence for clinical efficacy of this approach. C_LI