Abstract
Importance: Purpose in life is a critical aspect of psychological well-being that is associated with better cognitive outcomes across the continuum of dementia. To our knowledge, the natural history of purpose with onset of cognitive impairment has yet to be evaluated. Objective: To evaluate changes in purpose in life prior to and after onset of cognitive impairment. Design, Setting, and Participants: This cohort study used assessments of purpose in life and cognitive status from March 2006 to May 2021 in the Health and Retirement Study (HRS) and from May 2011 to November 2021 in the National Health and Aging Trends Study (NHATS). Exposure: Cognitive impairment at each wave based on established thresholds in HRS and NHATS. Main Outcomes and Measures: The main outcome was purpose in life, measured with the Ryff Measures of Psychological Well-Being in HRS and a validated item in NHATS. Results In HRS, 22 668 participants provided 50 985 assessments of purpose across all waves. In NHATS, 10 786 participants provided 53 880 assessments of purpose across all waves. In HRS, 58.3% of participants were female, with mean (SD) age of 64.76 (10.41) years at baseline; in NHATS, 57.4% were female, with mean (SD) age of 76.82 (7.71) years at baseline. Across waves, 6794 HRS participants (30%) and 4446 NHATS participants (41.2%) were in the cognitive impairment range. Accounting for demographic covariates and normative change in purpose, multilevel modeling indicated that standardized purpose in life declined significantly prior to onset of cognitive impairment (estimate for 10 years) in both HRS (b = −0.12; 95% CI, −0.17 to −0.07; P < .001) and NHATS (b = −0.10; 95% CI, −0.20 to −0.01; P = .03). Purpose declined significantly more rapidly following onset of cognitive impairment, with a standardized decline nearly 3 times larger compared with prior to impairment in HRS (b = −0.35; 95% CI, −0.41 to −0.29; P < .001) and 4 times larger in NHATS (b = −0.44; 95% CI, −0.53 to −0.34; P < .001). Conclusions and Relevance: In this cohort study, purpose in life declined with emergence of cognitive impairment. The decline before onset was too small to be useful to detect impending impairment in clinical settings. The steeper decline following impairment suggests that individuals are aware that their purpose is declining. Purpose may be an intervention target following cognitive impairment to maintain well-being and to reduce or slow emergence of behavioral symptoms associated with low purpose.