Depression is a leading mental health concern among young adults, and researchers have increasingly looked to biological factors to better understand its roots. Examples of these factors include cortisol, a hormone released during stress that helps the body respond to challenges, as well as C-reactive protein (CRP), a marker of inflammation in the body. Although both stress hormones and inflammation have been linked to depression, most studies have examined them separately, leaving it unclear how they may work together to shape mental health outcomes.
Recent research from Dr. Doan and colleagues explored how cortisol and CRP interact to predict depressive symptoms in a sample of 184 college-aged young adults. Participants completed surveys measuring depression and provided saliva and blood samples to assess cortisol reactivity during a stress task and baseline inflammation levels. The stress task required participants to give a speech and complete mental math in front of evaluators, a well-established method for inducing psychological stress. Researchers then analyzed whether cortisol responses to the stress task, CRP levels, or their interaction were associated with depressive symptoms.
The study found no direct relationship between cortisol or CRP alone and depression. However, there was a significant interaction between the two: among participants with low levels of inflammation, greater cortisol reactivity to stress was linked with fewer depressive symptoms, suggesting that a strong biological stress response may be beneficial in this context. In contrast, this benefit disappeared at higher levels of inflammation. Published in the journal Psychoneuroendocrinology, this study and its findings highlight the importance of considering how multiple biological systems interact, showing that the inflammatory environments can be a factor in whether stress response hormones play a role in the expression of depressive symptoms.