Older adults with higher cumulative daily cortisol levels experienced faster cognitive decline, while healthier day-to-day cortisol variability was linked to slower decline, suggesting that salivary cortisol may serve as an early biomarker of cognitive aging, although it was not associated with short-term Alzheimer’s disease (AD) risk. In this US prospective cohort study of 3,895 Black and White older adults (mean age 76.7 years) followed for up to 11 years, all measures of salivary cortisol were associated with cognitive performance at baseline. Longitudinally, participants with the highest cumulative cortisol exposure showed faster cognitive decline, whereas those with moderate to high intraday cortisol variability experienced slower decline. Measures of diurnal cortisol change, including the daily cortisol slope, were not associated with cognitive decline or incident AD. Black participants had lower overall cortisol exposure but flatter daily cortisol rhythms and lower intraday variability, indicating a more blunted cortisol pattern, although the relationship between cortisol and cognitive decline was similar across Black and White participants. These findings suggest that altered daily cortisol regulation is linked to neurocognitive aging and that racial differences in cortisol patterns may reflect the long-term biological effects of chronic stress and structural inequities. Source: https://jamanetwork.com/
