Effect of purpose in life on the relation between Alzheimer disease pathologic changes on cognitive function in advanced age.
Level 3 - non-randomized controlled study
Longitudinal clinicopathologic cohort study with postmortem neuropathology
PubMed 22566582 · doi:10.1001/archgenpsychiatry.2011.1487
What was done
Researchers evaluated 246 community-based older adults enrolled in the Rush Memory and Aging Project who completed annual clinical evaluations, structured interviews assessing purpose in life, and postmortem brain autopsy proximate to death. Neuropathologists quantified three indexes of Alzheimer disease (AD) pathology: global AD pathology, amyloid, and tangles. Linear regression and mixed-effects models tested whether purpose in life modified the relationship between AD pathology and both terminal cognitive function and prior rates of cognitive decline.
What was found
Purpose in life significantly modified the relationship between global AD pathology and cognitive function proximate to death (parameter estimate [SE]: 0.532 [0.211], P = .01), such that participants with higher purpose exhibited better cognitive performance despite disease burden. Purpose in life also reduced the negative association between tangles and cognition (parameter estimate [SE]: 0.042 [0.019], P = .03), which persisted after controlling for confounders. Longitudinal analyses showed higher purpose in life reduced the effect of AD pathology on the rate of cognitive decline (parameter estimate [SE]: 0.085 [0.039], P = .03).
Why it matters
These findings suggest that psychological purpose in life may provide cognitive reserve, dampening the clinical expression and cognitive decline typically driven by accumulating Alzheimer neuropathology in older age.
Limits
The sample was limited to 246 community-dwelling older adults who agreed to postmortem brain autopsy, which may introduce selection bias. As an observational cohort, it cannot establish causality. Results for amyloid alone were not reported separately in the abstract.
Cited by
- supports Having a strong sense of purpose in life makes individuals more resilient to cognitive decline over time.
- supports Psychosocial factors including having a sense of purpose and maintaining social connections provide cognitive resilience against developing dementia in the presence of Alzheimer's pathology.