Cortisol profile and depressive symptoms in diverse populations of older adults

Background: Cortisol, a biological response to stress, is elevated during acute stress, and blunted during chronic stress. These two patterns have been associated with elevated depressive symptoms. Most evidence comes from high income countries. Residents from two different countries can experience very diverse living conditions which can affect their stress systems. This has not been examined to date. Objective: To compare cortisol and its associations with concurrent depressive symptoms in older adults living in Santa Cruz, in an underdeveloped region of North East Brazil to that in older adults living in middle class St-Bruno, in Quebec, Canada. Methods: This study took place between October and December 2009. Cortisol awakening response (CAR, upon waking up, +30 and +60 minutes), and levels at 1500h and bedtime were measured in 65-74 years old adults living in Santa Cruz (n=64) and in St-Bruno (n=60). Participants also provided psychosocial information and an assessment of their depressive symptoms (CES-D scale). Associations between cortisol and depressive symptoms were examined using linear regressions analyses. Results: Brazilian residents had lower cortisol levels throughout the day, compared to Canadian residents. Elevated depressive symptoms (28.1% in Brazilian sample; 21.6% in Canadian sample) were associated with a blunted CAR in Brazilian residents, and greater overall cortisol output in the Canadian residents. Conclusion: Cortisol and its association with depressive symptoms differed between two diverse populations. Effects of stress, likely cumulative through the lifespan, may lead to chronic stress and a different relationship with elevated depressive symptoms compared to persons aging without lifelong adversity.