The PACt‐MD randomized clinical trial: Prevention of Alzheimer’s dementia with Cognitive remediation plus transcranial direct current stimulation in Mild cognitive impairment and Depression

Abstract

AbstractBackgroundInterventions to prevent cognitive decline and dementia in high‐risk populations such as those with remitted Major Depressive Disorder (rMDD) or Mild Cognitive Impairment (MCI) are urgently needed.MethodPACt‐MD was a double‐blind randomized trial conducted between 2015 and 2022 comparing cognitive remediation (CR) plus transcranial Direct Current Stimulation (tDCS) vs. sham‐CR+sham‐tDCS delivered 5 days/week for 8 weeks followed by 5‐day semi‐annual boosters and at‐home daily CR, in participants with rMDD or MCI. Participants were assessed at baseline, week‐8, and yearly.The hypotheses were that compared to sham+sham, CR+tDCS would: slow cognitive decline (H1); reduce progression to MCI or dementia (H2); and acutely improve cognition (H3).The primary outcome composite score was calculated when at least half of the tests for at least four of six cognitive domains were completed. Due to COVID‐19, some participants did not complete enough tests and a second composite score using all available data was generated.Result375 participants were randomized (Active: N = 188, Mean Age = 72.1 ± 6.3; Sham: N = 187, Mean Age = 72.3 ± 6.4) and received at least one intervention session. Over up to six years, there was no time‐by‐treatment interaction using the primary composite score but there was using the all‐data score. Change in composite score differed between the two intervention groups for the primary and all‐data scores for all years except for year‐6 primary score. The year‐5 adjusted z‐score difference was ‐0.15 (95%CI [‐0.29, ‐0.005]) for the primary and ‐0.21 (95%CI [‐0.34, ‐0.067]) for all‐data score (Fig.1). Comparing active vs. sham at 8‐week (H3), the adjusted z‐score difference was ‐0.06 (95%CI: [‐0.12, 0.005]; p = 0.072); and for progression (H2), HR was 0.66 (95%CI [0.40, 1.08] p = 0.101) in a stratified Cox model. In a preplanned secondary analysis of domain scores, there was a time‐by‐treatment interaction for verbal memory with a year‐5 adjusted z‐score difference of ‐0.30 (95%CI [‐0.53, ‐0.074]) (Fig.2) but not the other domains. In another preplanned secondary analysis, the model with a randomization diagnosis‐by‐time‐by‐treatment was different from the model without this three‐way interaction (p = 0.012; Fig.3).ConclusionCR+tDCS may be effective in slowing cognitive decline (particularly verbal memory) in older patients with rMDD or MCI.