Cognitive activity and age of onset of Alzheimer's disease dementia

First published on July 14, 2021 DOI: https: //doi.org/10.1212/WNL.00000000012388

Commentary

This study will test the hypothesis that higher levels of cognitive activity predict older age in the development of Alzheimer's disease (AD) dementia.

In a longitudinal cohort study, 1,903 older adults without dementia at enrollment reported the frequency of their participation in cognitive stimulation activities.

The participants underwent annual clinical evaluations and neuropathological testing to diagnose dementia and AD. The analysis assessed the relationship between baseline cognitive activity and postmortem markers of age at diagnosis of incident AD dementia, AD, and other dementias.

The results showed that 457 people were diagnosed with AD during the 6-8 year follow-up period. (SD = 6.4; range: 64.1-106.5)

The extended accelerated disability time model found that higher levels of baseline cognitive activity (mean = 3.2, SD = 0.7) were associated with older age at onset of AD dementia. Lower cognitive activity was also associated with a mean age of onset of AD of 88.6 compared to a mean age of onset of AD of 93.6 associated with higher cognitive activity.

These results were comparable after adjusting for potential confounders, and in the 695 participants who died and underwent neuropathological examination, cognitive activity was reported to be unrelated to AD or other postmortem markers of dementia.

These experiments suggest that a cognitively active lifestyle in old age may delay the onset of dementia in AD by as much as five years.