The predictive value of cortisol levels on 2-year course of depression in older persons

Background Depressive disorders in older persons are associated with an altered functioning of the Hypothalamic–Pituitary–Adrenal (HPA)-axis. In adults, a lower cortisol awakening response is a predictor of a worse prognosis of depression, but to date longitudinal studies in older depressed persons are lacking. We hypothesised that a lower cortisol awakening response is also associated with poorer course of depression in later life. Methods Data were derived from the Netherlands Study of Depression in Older Persons (NESDO). Participants with a 6-month Major Depressive Disorder (MDD), who provided 2-year follow-up data, were included (n = 246). Logistic regression analyses were conducted to examine the association between diurnal cortisol levels and depressive status at 2-year follow-up. Results Both lower (OR = 3.54; 95% CI = 1.59–7.89) and higher evening cortisol levels (OR = 2.41; 95% CI = 1.09–5.35) at baseline were associated with poorer prognosis of MDD. Low dexamethasone suppression was associated with poorer course (OR = 2.37; 95% CI = 1.09–5.16), but failed to reach significance after additional adjustment for severity and chronicity of MDD (OR = 1.98; 95% CI = 0.89–4.42). Cortisol awakening response was not significantly associated with course. Since smoking has a great impact on cortisol levels, we conducted post-hoc analyses including non-smokers only, indicating that lower evening cortisol levels (OR = 2.83, 95% CI = 1.31–6.13) predicted unfavourable course. Conclusions This first longitudinal study on cortisol and prognosis of depression in older persons demonstrates that in particular lower evening cortisol levels may predict poorer course in MDD. This finding may have clinical implications. Evening cortisol values may serve as a marker to identify persons at risk for an unfavourable course