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Racial and Ethnic Differences in Diurnal Cortisol Rhythms: Are They Consistent Over Time?

DeSantis, Amy S. PhD; Adam, Emma K. PhD; Hawkley, Louise C. PhD; Kudielka, Brigitte M. PhD; Cacioppo, John T. PhD

doi: 10.1097/PSY.0000000000000131
Original Articles

Background: Prior research indicates that blacks and Hispanics/Latinos have flatter diurnal cortisol declines across the day, a profile associated with poorer health. The stability of racial and ethnic differences in cortisol levels over time is not well understood, and additional research is needed to establish racial and ethnic differences in psychosocial stress levels as related to changes in cortisol levels.

Methods: With data from a community-based study of 152 adults (mean age = 58 years; 53% women; 34% black, 26% Hispanic/Latino), we examined the magnitude of racial and ethnic differences over a 5-year period. Salivary cortisol samples were obtained 3 times per day for 3 days in Years 1, 3, 4, and 5. Life events and chronic stress were assessed by questionnaires in which participants reported on whether they had experienced specific types of events or stress within the past year. Depressive symptoms scales (Center for Epidemiologic Studies of Depression Scale) were also administered annually. Daily cortisol slopes were calculated by subtracting wakeup cortisol from bedtime levels and dividing by hours awake.

Results: Increases in psychosocial stress were associated with flatter cortisol slopes among blacks (β = 0.010) and Hispanics/Latinos (β = 0.014), although including cardiovascular disease risk factors attenuates associations in blacks (β = 0.007; p = .125). Higher income predicts a steepening of cortisol rhythms across the study (β = −0.003; p = .019).

Conclusions: Racial and ethnic differences in diurnal cortisol rhythms are stable over time. However, the magnitude of changes in cortisol levels associated with chronic stress levels may vary by racial and ethnic subgroups.

From the Department of Social Sciences and Humanities (A.S.D.), Indian Institute of Technology–Gandhinagar, Ahmedabad, Gujarat, India; Program on Human Development and Social Policy (E.K.A.), Cells to Society: Center for Social Epidemiology and Health, Northwestern University, Evanston, Illinois; Academic Research Centers (L.C.H.), NORC, University of Chicago, Chicago, Illinois; Department of Medical Psychology and Psychological Diagnostics (B.M.K.), University of Regensburg, Regensburg, Germany; Department of Psychology and Center for Cognitive and Social Neuroscience (J.T.C.), University of Chicago, Chicago, Illinois.

Address correspondence and reprint requests to Amy S. DeSantis, PhD, Indian Institute of Technology–Gandhinagar, Ahmedabad, Gujarat, India. E-mail: desantis@iitgn.ac.in; desantis.amy@gmail.com; amydesantis2008@u.northwestern.edu

Received for publication October 22, 2012; revision received August 24, 2014.

Copyright © 2015 by American Psychosomatic Society