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

TLDR

Allostatic load (AL) has been proposed as a new conceptualization of cumulative biological burden exacted on the body through attempts to adapt to life's demands. The study evaluated whether a multisystem summary measure of allostatic load could predict four categories of health outcomes seven years after baseline in 1,189 adults aged 70–79. The allostatic load index comprised ten biological parameters, including four primary mediators of stress response and six secondary mediators related to metabolic syndrome. Higher baseline allostatic load predicted greater 7‑year mortality, cognitive and physical decline, and, to a lesser extent, cardiovascular events, outperforming syndrome X or individual mediator components, thereby supporting AL as a marker of cumulative biological burden.

Abstract

Allostatic load (AL) has been proposed as a new conceptualization of cumulative biological burden exacted on the body through attempts to adapt to life's demands. Using a multisystem summary measure of AL, we evaluated its capacity to predict four categories of health outcomes, 7 years after a baseline 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 associated with incident cardiovascular disease events, independent of standard socio-demographic characteristics and baseline health status. The summary AL measure was based on 10 parameters of biological functioning, four of which are primary mediators in the cascade from perceived challenges to downstream health outcomes. Six of the components are secondary mediators reflecting primarily components of the metabolic syndrome (syndrome X). AL was a better predictor of mortality and decline in physical functioning than either the syndrome X or primary mediator components alone. The findings support the concept of AL as a measure of cumulative biological burden.