Background
The negative correlation between life purpose levels and subsequent morbidity and mortality is interpreted as evidence that a higher sense of life purpose causes healthier and longer lives. Causation, however, could run the other direction as a decline in health is, by definition, associated with greater morbidity and mortality risk and may also cause a decline in life purpose. We examine the relation between objective measures of changes in health and changes in purpose to better understand the causal mechanisms linking purpose to health and mortality.
Methods
Prospective cohort sample of 12 745 individuals aged 50 and older who were eligible to participate in the 2006, 2010, or 2014 Health and Retirement Study Psychosocial and Lifestyle questionnaire. The final sample consists of 15 034 observations measured over three four-year periods from 5 147 individuals. Controlling for standard covariates, we examined the relation between changes in purpose and 14 contemporaneous and subsequent objectively measured changes in health--lung function, grip strength, walking speed, balance, and physician diagnoses of hypertension, diabetes, cancer, lung disease, heart condition, stroke, psychiatric problem, arthritis, dementia, and Alzheimer's disease.
Findings
There is strong evidence that negative health shocks cause a decline in life purpose as individuals who suffer a negative health shock experience a statistically meaningful contemporaneous decline in life purpose for 12 of the 14 changes in health metrics. In contrast, there is relatively weak evidence that a decline in purpose contributes to a deterioration of future health.
Interpretation
Much of the relation between life purpose levels and mortality risk arises from reverse causation--a decline in health causes both increased mortality risk and lower life purpose. There is little evidence that life purpose interventions would alter future morbidity or mortality.