Long-term cortisol in bipolar disorder: Associations with age of onset and psychiatric co-morbidity

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is hypothesized to play a role in the pathogenesis of bipolar disorder (BD). Conflicting results have been reported when saliva or serum was used to measure cortisol levels. A recently developed method is to measure cortisol in scalp hair, with 1 cm of scalp hair representing 1 month. We studied whether there are differences in long-term hair cortisol levels between BD patients and...