Investigating longitudinal associations of hair cortisol and cortisone with cognitive functioning and dementia.

We rigorously investigated potential longitudinal associations of hair cortisol and cortisone with verbal memory, time orientation, and dementia, adjusting for sociodemographic and health confounders. Data from the English Longitudinal Study of Ageing wave 6-9 (6-year follow-up, covering 4399 persons aged 50+) were analysed using linear random effects and cox regression models. In unadjusted models, hair cortisol was associated with worsened verbal memory (β 0.19; SE 0.08), but not with time orientation (β 0.02; SE 0.01), or dementia (β 0.07; SE 0.16). Hair cortisone was associated with worsened verbal memory (β 0.74; SE 0.14) and time orientation (β 0.06; SE 0.02), but not with dementia (β 0.47; SE 0.28). However, in the fully adjusted models, neither hair cortisol nor cortisone was associated with verbal memory, time orientation, or dementia. Consistent with prior studies, we found that more advanced age was associated with worsened verbal memory (β 0.15; SE 0.01), time orientation (β 0.01; SE 0.00), and dementia risk (β 0.11; SE 0.02). Our rigorous analyses did not detect robust associations of neither hair cortisol nor cortisone with cognitive functioning or dementia across 6 years. More detailed insights into potential mechanisms are discussed.