Day-to-day dynamics of experience–cortisol associations in a population-based sample of older adults

doi:10.1073/pnas.0605053103

Day-to-day dynamics of experience–cortisol associations in a population-based sample of older adults

*School of Education and Social Policy and Cells to Society Center, Institute for Policy Research, Northwestern University, Evanston, IL 60208;
^‡Department of Psychology and Center for Cognitive and Social Neuroscience, University of Chicago, Chicago, IL 60637; and
^§Graduate School of Psychobiology, University of Trier, 54290 Trier, Germany

Edited by Burton H. Singer, Princeton University, Princeton, NJ, and approved September 20, 2006 (received for review June 30, 2006)

Abstract

In 156 older adults, day-to-day variations in cortisol diurnal rhythms were predicted from both prior-day and same-day experiences, to examine the temporal ordering of experience–cortisol associations in naturalistic environments. Diary reports of daily psychosocial, emotional, and physical states were completed at bedtime on each of three consecutive days. Salivary cortisol levels were measured at wakeup, 30 min after awakening, and at bedtime each day. Multilevel growth curve modeling was used to estimate diurnal cortisol profiles for each person each day. The parameters defining those profiles (wakeup level, diurnal slope, and cortisol awakening response) were predicted simultaneously from day-before and same-day experiences. Prior-day feelings of loneliness, sadness, threat, and lack of control were associated with a higher cortisol awakening response the next day, but morning awakening responses did not predict experiences of these states later the same day. Same-day, but not prior-day, feelings of tension and anger were associated with flatter diurnal cortisol rhythms, primarily because of their association with higher same-day evening cortisol levels. Although wakeup cortisol levels were not predicted by prior-day levels of fatigue and physical symptoms, low wakeup cortisol predicted higher levels of fatigue and physical symptoms later that day. Results are consistent with a dynamic and transactional function of cortisol as both a transducer of psychosocial and emotional experience into physiological activation and an influence on feelings of energy and physical well-being.

Footnotes

^†To whom correspondence should be addressed at:
School of Education and Social Policy, Northwestern University, 2120 Campus Drive, Evanston, IL 60208.
E-mail: ek-adam{at}northwestern.edu
Author contributions: J.T.C. designed research; L.C.H. and B.M.K. performed research; E.K.A. analyzed data; and E.K.A., L.C.H., B.M.K., and J.T.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
↵ ¶ Because of the inclusion of a quadratic term for time of day, the linear time coefficient reflects the slope at Time = 0, which is time at wakeup in this model. Examination of the quadratic term reveals that the rate of decline in cortisol is approximately half as rapid at midday (8 hours later) and is close to zero by the end of the day (16 hours later).
↵ ‖ This analysis was repeated with time centered at 8 hours after awakening, such that the linear slope coefficient would reflect slope at midday. Similar effects of tension/anger were found for midday slopes (γ104 = 0.01, P = 0.05).
↵ ** A variety of health conditions were reported, including high blood pressure (41% of participants); a history of heart attack (4%), heart failure (4%), stroke (7%), cancer (9%); the presence of emphysema (4%), diabetes (18%), asthma (6%), rheumatoid arthritis (3%), ulcers (4%), kidney problems (3%), liver problems (2%); HIV⁺ status (1%); or psychiatric problems (details of diagnoses not specified) (12%). Only the presence of a psychiatric condition was significantly associated with our cortisol parameters; this variable was retained as a covariate.
↵ †† For the wakeup sample, participants were considered noncompliant if the track cap reading showed that they took the wakeup sample more than 10 min earlier or later than their self-reported wakeup time. For the CAR sample, participants were considered noncompliant if the time between the track cap readings for the wakeup and CAR samples deviated by >10 min from the requested 30-min interval.
Abbreviations:

CAR,

cortisol awakening response;

HPA,

hypothalamic–pituitary–adrenal;

n.s.,

not significant.