Feasibility and Preliminary Efficacy of the Lifestyle, Exercise and Diet (LEAD) Study: A Cluster Randomized Controlled Trial of a Combined Exercise and Diet Intervention in Older Adults with Vascular Risk Factors and Early Dementia Risk

Background: Healthy diet and exercise are associated with reduced risk of dementia in older adults. Evidence for the impact of clinical trials on brain health is less consistent, especially with dietary interventions which often rely on varying intervention approaches. Our objective was to evaluate the feasibility and preliminary efficacy of a 6-month intervention combining exercise with a novel dietary counselling approach among older adults with vascular risk factors (VRFs) and early dementia risk. Methods: Participants with VRF’s and SCD or early MCI were cluster randomized into the intervention (exercise + Baycrest Brain-healthy Eating Approach (EX+DIET)) or control group (exercise + brain health education (EX+ED)). Both groups participated in 1-hour of supervised exercise per week and were prescribed additional exercise at home. EX+DIET involved 1-hour per week of group-based dietary counselling comprising didactic education focused on brain healthy eating recommendations, goal setting and strategy training. Whereas, EX+ED involved 1-hour per week of group-based brain health education. The primary outcome was change in hippocampal volume from baseline to 6 months. Secondary outcomes included fitness, diet, cognition, and blood biomarkers. Recruitment challenges and early discontinuation of the trial due to COVID-19 necessitated a revised focus on feasibility and preliminary efficacy. Results: Of 190 older adults contacted, 14 (7%) were eligible and randomized, constituting 21% of our recruitment target. All participants completed the intervention and attended 90% of exercise and diet/education sessions on average. All 6-month follow-up assessments pre-COVID-19 were completed but disruptions to testing during the pandemic resulted in incomplete data collection. No serious adverse events occurred and all participants expressed positive feedback about the intervention. Mean improvements in peak oxygen consumption were observed in both EX+DIET ( d = .98) and EX+ED ( d = 1.15) groups. Substantial improvements in diet and HbA1c were observed in the EX+DIET group compared to EX+ED ( d = 1.75 and 1.07, respectively). Conclusions: : High adherence and retention rates were observed among LEAD participants and preliminary findings illustrate improvements in cardiorespiratory fitness and diet quality. These results indicate that a larger trial is feasible if difficulties surrounding recruitment can be mitigated. Trial Registration: ClinicalTrials.gov identifier: NCT03056508