Which predicts longevity better: Satisfaction with life or purpose in life?

Abstract

Life satisfaction and purpose in life are fundamental yet separate ways to evaluate one's life. Both positively predict physical health and longevity, making them key factors for length and quality of life. However, we do not know which of them predicts mortality, when controlling for the influence of each other. Given that purpose in life involves a more active engagement with life and can help to cope with suffering, we hypothesize that purpose in life could be a more direct prospective predictor of longevity, overshadowing any effect of life satisfaction, when the two are pitted against each other as prospective predictors of longevity. To examine these hypotheses, we utilized Midlife in the U.S. survey, which is a 23-year follow-up study, (N = 5,993) and Cox proportional hazards models, repeating the analyses both without covariates and when controlling for various demographic and health-related variables. We show that both life satisfaction and purpose in life predict mortality when modeled separately. When life satisfaction, purpose in life and self-rated health were entered as simultaneous predictors of mortality, purpose in life remained a slightly more robust predictor of mortality, while life satisfaction became only marginally significant, suggesting that some of the factors that connect it to mortality are covered by the other two subjective evaluations. Overall, the results demonstrate that purpose in life is a robust predictor of mortality, and thus a key dimension of well-being to attend to as people age, while the predictive power of life satisfaction is more dependent on the choice of covariates. Public Significance StatementWell-being is an important predictor of longevity. But which type of well-being predicts it best? This study compared purpose in life and life satisfaction as predictors of mortality, finding that the former was the more robust predictor of longevity. Thus, purpose in life is a key factor to attend to and strengthen, especially as people age.