Mickey BJ, et al. - Considering the previously described abnormalities of hypothalamic-pituitary-adrenal (HPA) axis function in severe forms of depression, researchers examined if the temporal trajectory of basal cortisol levels would vary among individuals with depression due to heterogeneity in pathophysiology, and if cortisol trajectories that reflect elevated or increasing HPA activity would predict better response to electroconvulsive therapy (ECT). They sampled scalp hair from 39 subjects with treatment-resistant depression just before ECT and reconstructed cortisol trajectory over the 12 weeks preceding ECT from cortisol concentrations in sequential hair segments. They noted that in this severely depressed sample, cortisol trajectory mapped onto symptoms of melancholia and independently predicted response to ECT.