This longitudinal observational study examined whether a brain-structure-informed social engagement index (9-item Felix Social Engagement Index) at baseline was associated with slower decline in memory, orientation, and executive function over 8 years (2011–2019) among 6,084 dementia-free, community-dwelling Medicare beneficiaries aged ≥65 (mean age 76.4 years), including the oldest-old.
Higher baseline social engagement significantly attenuated aging-related cognitive decline across all three domains after 8 years: memory (β = 0.14; p < 0.001), orientation (β = 0.14; p < 0.001), and executive function (β = 0.05; p < 0.001). Benefits were incremental — the highest engagement quartile (scores 8–9) provided the greatest protection across all domains.
- Reverse causation cannot be excluded: better baseline cognition may enable greater social engagement rather than the other way around. - NHATS lacks neuroimaging, so brain-structural links are inferred from a separate foundational DTI study, not directly measured here. - Cognitive assessment relies on brief screening subscales (word recall, clock draw, orientation items), not full neuropsychological batteries, risking ceiling/floor effects.
Encourage older adult patients to engage broadly across multiple social activities — marriage/cohabitation, driving, clubs, volunteering, religious services — as cumulative breadth of engagement (not any single activity) is linked to slower decline in memory, orientation, and executive function over nearly a decade. Even in highly educated populations, incremental gains from greater social engagement are detectable.
