Sense of purpose in life and inflammation in healthy older adults: A longitudinal study

Abstract

Background: A higher sense of purpose in life has been linked with reduced risk of age-related chronic health conditions that share elevated inflammation as a key risk factor (e.g., neurodegenerative diseases, heart disease, and diabetes). While prior research has documented cross-sectional associations between higher sense of purpose and lower inflammation, few studies have examined the association between purpose and changes in inflammation over time.

Objective: We tested if a higher sense of purpose was prospectively associated with lower likelihood of developing unhealthy C-reactive protein levels in older adults who initially had healthy CRP levels (i.e., <3 ug/mL).

Methods: Participants were 6925 adults aged > 50 in the Health and Retirement Study who were followed for 8 years. Participants completed the purpose in life subscale of the Ryff Psychological Well-being Scales at study baseline in 2006/2008. CRP was obtained from blood spots collected at baseline and after 4 and 8 years of follow-up. Pooled logistic regression estimated discrete-time hazard ratios (HR) and 95% confidence intervals (CI) for the association between baseline purpose and onset of unhealthy CRP levels (>3 ug/mL).

Results: There was no strong evidence of an association between baseline continuous purpose scores and onset of unhealthy CRP levels over time in the overall analytic sample. In sex-stratified models, higher purpose was associated with lower hazards of developing unhealthy CRP levels among men, while associations were null in women (e.g., in sociodemographics-adjusted model, men: HR=0.89, 95% CI: 0.79-0.99; women: HR=0.96, 95% CI: 0.85-1.08; interaction between continuous purpose scores and sex p = 0.15).

Conclusions: Findings suggest that a higher versus lower sense of purpose is associated with lower inflammation levels in older men. In specific populations, purpose may serve as a novel target for future interventions aimed at reducing inflammation.

Keywords: C-reactive protein; Epidemiology; Health psychology; Inflammation; Longitudinal Studies; Purpose in life.

Figure 1.. Sample flow chart.

The number of excluded individuals and size of remaining samples are calculated based on the first of the five imputed datasets. Because the sample selection was conducted after imputation for missing data, the final analytic sample sizes varied and ranged from 6,884 to 6,932 across imputations.