Racial and ethnic differences in diurnal cortisol rhythms: are they consistent over time?

Area of Science:

• Endocrinology
• Health Disparities
• Psychosocial Stress Research

Background:

• Previous studies show flatter diurnal cortisol declines in Black and Hispanic/Latino individuals, linked to poorer health outcomes.
• The long-term stability of these racial and ethnic differences in cortisol levels requires further investigation.
• Understanding the relationship between psychosocial stress and cortisol changes across racial/ethnic groups is crucial.

Purpose of the Study:

• To examine the stability of racial and ethnic differences in diurnal cortisol rhythms over a 5-year period.
• To investigate the association between psychosocial stress and cortisol level changes in diverse adult populations.
• To explore how socioeconomic factors and health conditions influence these relationships.

Main Methods:

• Longitudinal community-based study of 152 adults (34% Black, 26% Hispanic/Latino).
• Salivary cortisol measured 3 times daily for 3 days annually over 5 years.
• Life events, chronic stress, and depressive symptoms assessed annually; cortisol slopes calculated.

Main Results:

• Increased psychosocial stress correlated with flatter cortisol slopes in Black and Hispanic/Latino individuals.
• Cardiovascular disease risk factors attenuated stress-cortisol associations in Black individuals.
• Higher income was associated with steeper diurnal cortisol rhythms over time.

Conclusions:

• Racial and ethnic differences in diurnal cortisol patterns are stable over the 5-year study period.
• The impact of chronic stress on cortisol level changes may differ across racial and ethnic subgroups.
• Findings underscore the persistent nature of biological responses to stress and socioeconomic factors across diverse populations.