Associations between hypothalamic-pituitary-adrenal (HPA) axis hormone levels, major depression features and antidepressant effects of ketamine.

Baseline levels of stress-related hormones (CRF, ACTH, and cortisol) did not significantly influence how well ketamine worked as an antidepressant in people with treatment-resistant depression. However, higher levels of ACTH and CRF were associated with longer overall duration of depressive episodes, suggesting these hormones might serve as biomarkers for chronic depression. Additionally, people who developed depression at a younger age tended to have more severe depressive symptoms, indicating that earlier onset may lead to greater cumulative stress on the brain and body. The study involved 42 participants in a randomized, placebo-controlled, crossover trial.

Study at a glance

Abstract

Subanesthetic doses of (R,S)-ketamine (ketamine) have demonstrated rapid and robust antidepressant effects in individuals with depression. However, individual variability in response to ketamine exists, and current biomarkers of ketamine treatment response are not entirely understood. Preclinical evidence suggests a link between hypothalamic-pituitary-adrenal (HPA) axis activation, a determinant of the stress response system, and ketamine's efficacy in stressed mice exhibiting enhanced antidepressant responses. Here, we assessed the relationship between HPA axis, major depression features, and antidepressant response to ketamine in humans. We investigated 42 participants following medication washout with treatment-resistant depression who participated in a randomized, placebo-controlled, crossover trial receiving intravenous ketamine. Plasma levels of corticotropin-releasing factor (CRF), adrenocorticotropic hormone (ACTH), and cortisol were measured at baseline. Ketamine's antidepressant effects were assessed using the Montgomery-Asberg Depression Rating Scale. We found that baseline HPA axis hormone levels did not significantly moderate the antidepressant effects of ketamine. However, a negative association was observed between ACTH and CRF levels and the overall duration of depressive episodes, suggesting potential biomarker implications. Also, a negative correlation between baseline depressive scores and age of onset was observed, suggesting that the severity of depression might be greater if it develops at a younger age, indicating more enduring stress on the brain and body. Although we did not find a moderation effect of the plasma HPA axis hormones on the antidepressant effects of ketamine, moderation effects of the brain HPA axis hormones cannot be precluded and warrants further investigation. Importantly, our results implicate HPA axis components as potential biomarkers for the duration of depressive episodes.