Graduation Year


Date of Submission


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts


W.M. Keck Science Department

Reader 1

Stacey Doan

Reader 2

Cathy Reed

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According to the World Health Organization (2021), depression is the leading cause of disability worldwide, so it is imperative to understand biological mechanisms and vulnerability factors that contribute to its development. Previous literature has shown markers of inflammation (CRP) and cortisol (the end-product of the hypothalamic-pituitary-adrenal axis, one of the body’s main stress response systems) to be associated with depressive symptoms (Bhagwagar et al., 2005; Dienes et al., 2013; Hinkelmann et al., 2009; Howren et al., 2009; Keller et al., 2006; Pitharouli et al., 2021; Wium-Andersen et al., 2013; Yang et al., 2015). However, the extent to which immune and stress responses interact on a physiological level, and contribute to depression, is poorly understood. The present study sampled 126 participants (Mage = 19.26, 59.5% female), and aimed to investigate the relationship between cortisol, and CRP and their main and interactive relations with depression during the COVID-19 pandemic. Results suggest that cortisol is a predictor of COVID-19 depression. Importantly, however, the effect is moderated by CRP, such that the effect was only significant at higher levels of CRP. These findings contribute to a growing area of research investigating vulnerability factors of depression, the way that the immune and stress systems interact together in relation to depression, and the pandemic’s biological impact on emerging adults.

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.