Afternoon salivary cortisol shows no association with same-day state anxiety in community-dwelling older adults during the COVID-19 pandemic.

Objectives: Older adults experienced measurable psychological burden during the COVID-19 pandemic. Although salivary cortisol is widely used as a biomarker of hypothalamic-pituitary-adrenal axis activity, single time-point basal measurements may show inconsistent associations with anxiety. We examined whether afternoon salivary cortisol was cross-sectionally associated with same-day state anxiety in community-dwelling older adults during the COVID-19 pandemic. Methods: Community-dwelling adults aged ≥65 years were recruited between May and November 2021 in rural Japan. Afternoon salivary cortisol (15:00-16:00) was measured using enzyme-linked immunosorbent assay from stored samples. State anxiety was assessed using the State-Trait Anxiety Inventory state scale (STAI-State). Multivariable linear regression models were fitted in the overall sample and in exploratory sex-stratified analyses, adjusting for demographic, psychological, cognitive, and COVID-19-related factors. Results: The analyses included 76 participants (mean age 80.8 years; 68% female). The mean (standard deviation) STAI-State score was 40.7 (10.5), and median salivary cortisol was 0.13 μg/dL. In adjusted models, salivary cortisol was not associated with STAI-State score in the overall sample or in exploratory sex-stratified analyses. Effect estimates were close to null. Conclusions: In this cohort of community-dwelling older adults in Japan during the COVID-19 pandemic, a single afternoon salivary cortisol measurement was not associated with same-day state anxiety. This null finding should be interpreted in the context of the present study design and measurement approach and does not rule out an association between cortisol and anxiety under other conditions.