Allostatic Load and Frailty in Older Adults

OBJECTIVES: To examine the association between allostatic load (AL), an index of multisystem physiological dysregulation, and frailty development over a 3-year follow-up in a sample of older adults. DESIGN: Longitudinal cohort study. SETTING: Community. PARTICIPANTS: High-functioning men and women aged 70 to 79 at study entry. MEASUREMENTS: Multisystem physiological dysregulation, or AL, was assessed according to 13 biomarkers of cardiovascular, endocrine, immune, and metabolic function. An AL score was computed as the total number of biomarkers for which participant values fell into high-risk biomarker quartiles. Frailty status (not frail, intermediate frail, frail) was determined according to the total number of five indicators of frailty: weight loss, exhaustion, weak grip, slow gait, and low physical activity. The association between level of AL at baseline and frailty status 3 years later was examined using ordinal logistic regression in 803 participants not frail at baseline. RESULTS: In a multivariable model adjusting for sociodemographic, health, and behavioral characteristics, each 1-unit increase in AL at baseline was associated with a 10% greater likelihood of frailty at the 3-year follow-up (cumulative adjusted odds ratio = 1.10, 95% confidence interval = 1.03-1.19). CONCLUSION: These findings support the hypothesis that dysregulation across multiple physiological systems is associated with greater risk of frailty. Greater levels of multisystem physiological dysregulation may serve as a warning sign of frailty development in later life. J Am Geriatr Soc 57:1525-1531, 2009.