Design and Rationale of 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

Background By the time Alzheimer's disease and related disorders (ADRD) are diagnosed, efficacy of treatments is limited. Preventive interventions are urgently needed. Objective To design a randomized controlled trial to assess a novel intervention that aims to prevent ADRD in high-risk groups. Methods We report on the rationale and describe the design of a multisite randomized controlled trial that aims to prevent ADRD in older persons with: (1) mild cognitive impairment (MCI); (2) remitted major depressive disorder (MDD) without MCI; or (3) remitted MDD with MCI. Results PACt-MD (Prevention of Alzheimer's dementia with Cognitive remediation plus transcranial direct current stimulation in Mild cognitive impairment and Depression) is a trial that randomized 375 older participants with MCI, MDD, or MCI + MDD to cognitive remediation (CR) plus transcranial direct current stimulation (tDCS) or sham-CR + sham-tDCS for 5 days/week for 8 weeks followed by boosters for 5 days/week once every 6 months until participants progress to MCI or ADRD, or the end of the study. Between boosters, participants are asked to train on CR daily. At baseline, end of 8 weeks, and yearly from baseline, participants undergo clinical, cognitive, and functional assessments. The primary aims are to compare the efficacy of CR + tDCS versus sham + sham in preventing: 1) long-term cognitive decline; and 2) incidence of ADRD or MCI. The secondary aim is to assess for cognitive improvement after the 8-week course. We will also explore the moderating and mediating effects of several biomarkers collected from the participants. Conclusion PACt-MD is unique in combining brain stimulation and a psychosocial intervention to prevent ADRD. PACt-MD is also a platform for studying multi-domain biomarkers that will advance our understanding of the relationships among MCI, MDD, and ADRD.