Salivary cortisol emerges as a potential early marker of cognitive aging

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Salivary cortisol emerges as a potential early marker of cognitive aging

In a large prospective cohort of nearly 3,900 older adults followed for up to 11 years, altered daily cortisol patterns were associated with faster cognitive decline, although they were not linked to short-term Alzheimer's disease risk.

The findings, published in JAMA Network Open, suggest that salivary cortisol could serve as an early biomarker of neurocognitive aging and highlight racial differences in stress-related biological patterns that may inform future research and prevention strategies.

“In this cohort study examining salivary cortisol levels and cognitive decline, across the 5 salivary cortisol indices, distinct yet complementary patterns emerged that reflect distinct aspects of diurnal cortisol patterning and associations with cognitive decline,” wrote Ted K. S. Ng, PhD, Rush University Medical Center, Chicago, Illinois, and colleagues. “All indices were associated cross-sectionally with cognitive performance…when participants with the lowest 10% of baseline cognitive performance were excluded, mean cortisol remained significant, underscoring its robustness as an early physiological marker associated with subsequent cognitive decline among cognitively healthy adults.”

For the study, the researchers analysed data from 3,895 Black and White older adults (mean age, 76.7 years) enrolled in the Chicago Health and Aging Project, measuring salivary cortisol at waking, afternoon, and bedtime and following participants for cognitive outcomes over 11 years. Five cortisol indices reflecting daily hormone variability, cumulative exposure, and diurnal change were evaluated in relation to global cognition, cognitive decline, and incident Alzheimer's disease.

Higher cumulative cortisol exposure was associated with faster cognitive decline, with participants in the highest quintile of mean cortisol (β = -0.02; P = .02) and area under the curve (β = -0.02; P = .046) experiencing greater decline over time. In contrast, moderate-to-high intraday cortisol variability was associated with slower cognitive decline (Q3 β = 0.02; P = .04; Q4 β = 0.03; P = .003).

No cortisol measure was associated with incident Alzheimer's disease during follow-up.

Black participants exhibited lower overall cortisol exposure but flatter daily cortisol slopes and lower intraday variability than White participants, although the relationship between cortisol patterns and cognitive decline was similar across racial groups.

“Because cortisol patterns may be responsive to behavioural, pharmacologic, and social interventions, these findings underscore opportunities for precision prevention and equity-informed strategies targeting stress-related cognitive aging,” the authors wrote.

Reference: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2851652

SOURCE: JAMA Network Open