Structured vs Self-Guided Multidomain Lifestyle Interventions for Global Cognitive Function

Importance: Identifying new interventions to slow and prevent cognitive decline associated with dementia is critical. Nonpharmacological interventions targeting modifiable risk factors are promising, relatively low-cost, accessible, and safe approaches. Objective: To compare the effects of two 2-year lifestyle interventions on cognitive trajectory in older adults at risk of cognitive decline and dementia. Design, Setting, and Participants: Single-blind, multicenter randomized clinical trial enrolling 2111 participants from May 2019 to March 2023 (final follow-up, May 14, 2025) at 5 clinical sites in the US. Participant inclusion criteria enriched risk of cognitive decline and included age 60 to 79 years, sedentary lifestyle, and suboptimal diet plus at least 2 additional criteria related to family history of memory impairment, cardiometabolic risk, race and ethnicity, older age, and sex. Interventions: Participants were randomly assigned with equal probability to structured (n = 1056) or self-guided (n = 1055) interventions. Both interventions encouraged increased physical and cognitive activity, healthy diet, social engagement, and cardiovascular health monitoring, but differed in structure, intensity, and accountability. Main Outcomes and Measures: The primary comparison was difference between intervention groups in annual rate of change in global cognitive function, assessed by a composite measure of executive function, episodic memory, and processing speed, over 2 years. Results: Among the 2111 individuals enrolled (mean age, 68.2 [SD, 5.2] years; 1455 [68.9%] female), 89% completed the year 2 assessment. The mean global cognitive composite z score increased from baseline over time in both groups, with a mean rate of increase per year of 0.243 SD (95% CI, 0.227-0.258) for the structured intervention and 0.213 SD (95% CI, 0.198-0.229) for the self-guided intervention. The mean rate of increase per year was statistically significantly greater for the structured group than the self-guided group by 0.029 SD (95% CI, 0.008-0.050; P = .008). Based on prespecified secondary subgroup comparisons, the structured intervention benefit was consistent for APOE ε4 carriers and noncarriers (P = .95 for interaction) but appeared greater for adults with lower vs higher baseline cognition (P = .02 for interaction). Fewer ascertained adverse events were reported in the structured group (serious: 151; nonserious: 1091) vs the self-guided group (serious: 190; nonserious: 1225), with a positive COVID-19 test result being the most common adverse event overall and more frequent in the structured group. Conclusions and Relevance: Among older adults at risk of cognitive decline and dementia, a structured, higher-intensity intervention had a statistically significant greater benefit on global cognition compared with an unstructured, self-guided intervention. Further investigation of functional outcomes, biomarkers, and ongoing extended follow-up will help address clinical relevance and sustainability of the observed cognitive benefits. Trial Registration: ClinicalTrials.gov Identifier: NCT03688126.