Data from: Longitudinal associations between diurnal cortisol variation and later life cognitive impairment

Objective: To determine whether HPAA dysfunction is prospectively
associated with global cognitive impairment in later life Methods: This
cross-cohort study integrates two large longitudinal datasets: Whitehall
II and the National Survey for Health and Development (NSHD), on data
collected in the Whitehall II study in 2002/2004, 2007/2009 and 2012/2013;
and for NSHD in 2006/2010 and 2015. Serial salivary cortisol samples were
collected multiple times within a 24-hour period at mean ages 61.2 and
65.9 years in Whitehall II and at age 60-64 from NSHD participants.
Cortisol profile is defined using cortisol awakening response (CAR) and
am:pm ratio. Cognitive function was measured using the MMSE in Whitehall
II and ACE-III in NSHD, harmonised into a thirty-point score. Models were
adjusted for age, sex, diagnoses of hypertension, diabetes, BMI,
educational attainment and interval between HPAA and cognitive
assessments. Results: In fully adjusted models, increased am:pm cortisol
ratio was prospectively associated with better later-life cognitive
function years later (0.02 fewer errors per SD increase in am:pm cortisol
ratio, p<0.01) and verbal fluency (0.03 SD increase in verbal
fluency per SD increase in am:pm ratio, p<0.01). Increasing age,
lower educational attainment, diagnosis of hypertension, diagnosis of
diabetes and increased BMI were associated with worse cognitive function
and poorer verbal fluency. There were no associations between depression
and later-life cognition or reverse associations between cognition and
later-life cortisol profiles. Conclusions: Loss of diurnal HPAA variation
is evident in individuals subsequently experiencing more cognitive
impairment. It may serve as an early pre-clinical marker of cognitive
decline.