Background Physical activity, healthy body weight, smoking, and alcohol consumption are each related to mortality, physical and cognitive function, and mental health but their combined long-term effect is unknown. We examined the individual and combined influence of these risk factors on mortality and subjective and measured function in middle-aged adults followed for 18 years.

Methods Data were from the US Health and Retirement Study (HRS), a biennial, longitudinal, nationally representative survey of older adults. 11,597 participants aged 51 to 61 were followed from study enrolment for an 18-year period. A health behaviour score was calculated with one point for each behaviour: moderate physical activity three times per week; BMI 20 to 25; alcohol consumption less than 7 drinks/week; non-smoking. Outcomes were all-cause mortality, problems with activities of daily living (ADLs), lung function, grip strength, walk speed, measured cognitive function, and depressive symptoms. Adjusted logistic and linear regression models were used to examine the relationships between health behaviours and outcomes separately by gender.

Results For all outcomes except grip strength there was a dose-response relationship between healthy behaviour score and outcomes. For example, in men with four healthy behaviours and no baseline ADL problems, at 18-year follow-up 78.4% had no ADL problems, 6.6% had ADL problems, and 15.0% had died. In men with no healthy behaviours and no ADL problems at baseline, at follow-up 35.1% had no ADL problems, 8.8% had ADL problems, and 56.1% had died. Results in women were comparable but ADL differences were more marked. Number of healthy behaviours was related to follow-up cognitive function, mental health, walk speed, and lung function but not grip strength. Results were robust to adjustment for socioeconomic status (SES: measures of health, income, and level of education) and in analyses stratified by SES similar differences were found in relation to healthy behaviours within strata.

Conclusion Simple differences in lifestyle behaviours in middle age are associated with major differences in mortality, functioning and health risks as people progress into old age. Effective health promotion in these age groups could bring substantial health benefits for individuals across SES groups.