Linking cognitive and behavioral reserve: Evidence from the CAN-PROTECT study.

Introduction: Changes to the brain due to Alzheimer's disease and other age-related neuropathologies may present with cognitive and behavioral symptoms, even during preclinical and prodromal stages. While cognitive reserve is known to mitigate cognitive decline in the preclinical stages of Alzheimer's disease, links between cognitive reserve and behavioral symptoms remain unclear. This study investigates the relationship between cognitive reserve and mild behavioral impairment (MBI), a neurodegenerative behavioral prodrome.

Methods: We analyzed cross-sectional data from 1204 participants in the Canadian Platform for Research Online to Investigate Health, Quality of Life, Cognition, Behavior, Function, and Caregiving in Aging (CAN-PROTECT) study. A cognitive reserve score (CRS) was generated based on education, occupation, and personal cognitive reserve proxies. MBI presence (MBI+) and MBI global and domain symptom severity were evaluated using the self-reported MBI Checklist. Initial analyses examined the convergent validity of the CRS through associations with objective neuropsychological test performance and self-reported cognitive symptoms (Everyday Cognition [ECog-II] scale). Models were also fitted to assess MBI status and severity as functions of the CRS.

Results: Higher CRS was associated with better neuropsychological test scores, lower odds of subjective cognitive decline (OR = 0.86, 95% CI: [0.76, 0.98], = .03), and lower ECog-II total score. Likewise, higher CRS was associated with lower odds of MBI+ (OR = 0.81, 95% CI: [0.71, 0.93], = .003), and lower MBI symptom severity globally, and in impulse dyscontrol and social inappropriateness domains.

Discussion: We provide preliminary evidence that engagement in activities known to preserve cognitive function in aging and disease may also preserve behavioral function. Future research should disentangle possible pathways through which cognitive reserve may preserve both cognition and behavior, explore common etiologies for these symptoms, and observe outcomes longitudinally to better understand these relationships.

Highlights: Education, occupation, and personal activities are cognitive reserve proxies.Cognitive reserve is linked to lower subjective cognitive decline in older persons.Cognitive reserve is linked to lower mild behavioral impairment odds and severity.