The mediating role of allostatic load in the relationship between early life adversity and cognitive function across the adult lifespan.

Early life adversity is consequential for poor cognitive health in mid to late-life. Early life adversity is associated with higher allostatic load, a biological indicator of physiological dysregulation due to cumulative wear-and-tear from chronic stress. Higher allostatic load is also associated with poorer cognitive function across the lifespan. To date, a paucity of research has examined allostatic load as a mechanism through which early life adversity impacts cognition in adulthood. Using cross-sectional data from the Midlife in the United States (MIDUS) Study, the objective of the current study was to investigate the mediating role of allostatic load in the relationship between early life adversity and cognitive performance (global cognition, episodic memory, executive function) among middle-aged and older adults without cognitive impairment (n = 1541, M=53 ± 12, 53% female). Early life adversity was measured retrospectively using the Childhood Trauma Questionnaire. Allostatic load was composed of 20 biomarker proxies of neuroendocrine, metabolic, inflammatory, and cardiovascular systems, stratified by sex. Cognitive performance was evaluated using a battery of standardized neuropsychological tests. Controlling for age, education, and race, allostatic load significantly mediated the relationship between early life adversity and global cognition (ß=-0.01, 95%CI [-0.01,-0.001]), and early life adversity and executive function (ß=-0.01, 95%CI [-0.01,-0.001]), but not episodic memory. Findings did not change after controlling for lifestyle behaviours and current depression. Consistent with the biopsychosocial lifespan model of cognitive aging, findings suggest that early life adversity may become biologically embedded over time to negatively impact cognitive function in later adulthood in a domain-specific manner.