The cortisol awakening response is related to executive function in older age

Changes in the cortisol awakening response (CAR) have been reportedly associated with older age and may reflect changes in cognitive performance. However methodological issues around adherence, in regard to careful timing of the CAR, suggest caution in drawing firm conclusions. More investigation is also needed regarding which cognitive domains may be most relevant. Executive Function (EF) is linked strongly to functioning of the frontal cortex, itself linked to cortisol secretion via regulation of the Hypothalamic Adrenocortical Axis. In this study, cortisol profiles, cognitive performance and adherence were carefully assessed in a sample of 50 older participants, aged 60-91 years (mean = 74 years). Key aspects of EF were assessed using Form B of the standard Trail-making Test controlling for time taken to complete the simpler Trail-A form of the test. Strong associations between CAR profiles and EF were evident. Cortisol measures significantly predictive of superior EF-related performance in a regression analysis were: earlier peaking and greater magnitude of the CAR. Together these measures explained fully a quarter of all the variance in test performance (R-2=0.25; F=7.90; df=2,47; p<.001). Cognitive tests of declarative memory, often linked to hippocampal functioning, were not associated with CAR profiles. We conclude that in a population of healthy older adults aspects of the CAR may be strongly, and perhaps with some degree of specificity, associated with that domain of cognitive functioning, EF, which seems to depend crucially on the integrity of frontal cortex circuitry. (C) 2012 Elsevier B.V. All rights reserved.