Antecedent longitudinal changes in body mass index are associated with diurnal cortisol curve features: The multi-ethnic study of atherosclerosis

Context: Prior studies have shown a cross-sectional association between body mass index (BMI) and salivary diurnal cortisol profile features (cortisol features); however, to our knowledge prior population-based studies have not examined the longitudinal association of body-mass index (BMI) with cortisol features.

Objective: To examine the association of (1) prior annual BMI percent change over 7years with cortisol features, (2) baseline cortisol features with subsequent change in BMI over 6years and (3) the association of change in cortisol features with change in BMI over 6years.

Design: Longitudinal study.

Setting: Multi-Ethnic Study of Atherosclerosis (MESA) Stress I & II Studies (2004-2006 & 2010-2012).

Participants: 1685 ethnically diverse men and women attended either MESA Stress exam (mean age 65±10years at MESA Stress I; mean age 69±9years at MESA Stress II).

Outcome measures: Log-transformed cortisol features including wake-up cortisol, cortisol awakening response, early decline slope (30min to 2h post-awakening), late decline slope (2h post-awakening to bedtime), bedtime, and total area under the curve (AUC) cortisol.

Results: Over 7years, following multivariable adjustment, (1) a 1% higher prior annual BMI % increase was associated with a 2.9% (95% CI: -5.0%, -0.8%) and 3.0% (95% CI: -4.7%, -1.4%) lower current wake-up and total AUC cortisol, respectively; (2) there was no significant association between baseline cortisol features and subsequent change in BMI and (3) among participants with BMI≥30kg/m², flattening of the late decline slope was associated with increases in BMI (every 1-unit increase late decline slope were associated with a 12.9% increase (95%CI: -1%, 26.8%) in BMI, respectively).

Conclusions: We found a significant association between prior annual BMI % change and cortisol features, but no significant association between baseline cortisol features and subsequent change in BMI. In participants with obesity increases in BMI were associated with less pronounced declined. Collectively, our results suggest that greater adiposity may lead to a blunted diurnal cortisol profile.