Adherence and intensity in multimodal lifestyle-based interventions for cognitive decline prevention: state-of-the-art and future directions

Preventing dementia and Alzheimer's disease (AD) is a global priority. Multimodal interventions targeting several risk factors and disease mechanisms simultaneously are currently being tested worldwide under the World-Wide FINGERS (WW-FINGERS) network of clinical trials. Adherence to these interventions is crucial for their success, yet there is significant heterogeneity in adherence reporting across studies, hindering the understanding of adherence barriers and facilitators. This article is a narrative review of available evidence from multimodal dementia prevention trials. A literature search was conducted using medical databases (MEDLINE via PubMed and SCOPUS) to select relevant studies: nonpharmacological multimodal interventions (i.e., combining three or more intervention domains), targeting individuals without dementia, and using changes in cognitive performance and/or incident mild cognitive impairment or dementia as primary outcomes. Based on the findings, we propose future adherence reporting to encompass both participation (average attendance to each intervention component) and lifestyle change using dementia risk scores (e.g., the LIBRA index). Moreover, we provide an estimation of the expected intensity of multimodal interventions, defined as the ratio of the expected dose (i.e., the overall amount of the intervention offered specified in the trial protocol) to duration (in months). Adjusting the expected dose by average adherence enables estimation of the observed dose and intensity, which could be informative for identifying optimal dosage thresholds that maximize cognitive benefits across different populations. Finally, this article provides an overview of the determinants of adherence to multimodal interventions, emphasizing the need for improved adherence reporting to inform the design and implementation of precision prevention interventions.