Late-life social activity and subsequent risk of dementia and mild cognitive impairment

Social activity is associated with better cognitive health in old age. To better translate epidemiological research for public health communication, we estimated relations of levels of social activity to average age at dementia onset.

In the Rush Memory and Aging Project (MAP), we followed 1923 dementia-free older adults and conducted annual clinical evaluations of dementia/mild cognitive impairment (MCI).

During a mean follow-up of 6.7 (SD = 4.7) years, 545 participants developed dementia, and 695 developed MCI. Using Accelerated Failure Time models adjusted for age, sex, education, race/ethnicity, and marital status, we found predicted mean age of dementia onset for the least socially active was 87.7 years, approximately 5 years earlier than the most socially active (mean age = 92.2, p < .01); we found a similar 5-year difference in age at MCI onset by social activity.

Our findings highlight the value of social activity as a possible community-level intervention for reducing dementia.

Accelerated failure time models estimated age at dementia onset by social activity level to aid interpretation. Higher social activity was associated with a 5-year older age at dementia onset. Economic research shows a 5-year delay translates to US$500,000 of healthcare savings per capita. Our findings help understand the public health significance of social activity.