Higher cortisol levels may proceed a manic episode and are related to disease severity in patients with bipolar disorder

Abstract

Background: Regulation of the hypothalamic-pituitary-adrenal (HPA) axis is implicated in the pathogenesis of bipolar disorder (BD). However, the relationship between HPA-activity and disease severity is not fully elucidated. In this pilot study we aimed to explore the temporal relationship between HPA-activity and the risk of a manic episode in BD patients type I, by assessing long-term hair cortisol concentrations (HCC). Second, we explored the relation between HCC and the number of previous episodes. Methods: Hair samples were collected from 45 BD I patients in euthymic or manic state and compared to 17 controls. From each participant, two hair samples of 3 cm length were used to measure long-term cortisol, reflecting retrospect time frames of 1–3 months and 4–6 months respectively prior to sampling. Results: HCC in the BD group was slightly higher than in the control group in both hair segments (p = 0.049 and 0.03; after adjustment for age, sex, BMI and hair washing frequency p = 0.222 and 0.139). A significant peak in hair cortisol was observed prior to a manic episode (p = 0.036). Furthermore, we found a positive correlation between the number of mood episodes HCC (p = 0.03). Conclusions: Our results indicate that long-term cortisol levels are slightly higher in BD, and in particular elevated in the months prior to a manic relapse. In addition HCC are positively associated with the number of previous mood episodes in the course of BD type I.