Allostatic load as a marker of cumulative biological risk: MacArthur studies of successful aging

Allostatic load (AL) has been proposed as a new conceptualization of cumula tive biological burden exacted on the body through attempts to adapt to lif e's demands. Using a multisystem summary measure of AL, we evaluated its ca pacity to predict four categories of health outcomes, 7 years after a basel ine survey of 1,189 men and women age 70-79. Higher baseline AL scores were associated with significantly increased risk for 7-year mortality as well as declines in cognitive and physical functioning and were marginally assoc iated with incident cardiovascular disease events, independent of standard socio-demographic characteristics and baseline health status. The summary A L measure was based on 10 parameters of biological functioning, four of whi ch are primary mediators in the cascade from perceived challenges to downst ream health outcomes. Six of the components are secondary mediators reflect ing primarily components of the metabolic syndrome (syndrome X). AL was a b etter predictor of mortality and decline in physical functioning than eithe r the syndrome X or primary mediator components alone. The findings support the concept of AL as a measure of cumulative biological burden.