DIFFERENTIAL ASSOCIATIONS OF DEPRESSION AND ANXIETY WITH STRESS-RELATED BIOMARKERS

<p dir="ltr">There is research linking depression and anxiety with markers of chronic stress, including cortisol dysregulation and systemic inflammation. However, it is unclear whether these associations reflect disorder-specific features or shared general distress, as diagnostic criteria and overlapping measures often conflate symptoms of both conditions. Using data from the MIDUS 2 and MIDUS Refresher studies, we examined diurnal cortisol slope (DCS), C-reactive protein (CRP), interleukins (IL-6 & IL-10), tumor necrosis factor-α (TNF-α), and low-frequency heart rate variability (LF-HRV; examined exploratorily) in relation to common and unique symptom dimensions assessed by the Mood and Anxiety Symptom Questionnaire (MASQ): general distress (common to both depression and anxiety), anhedonia (specific to depression), and anxious arousal (specific to anxiety). Across two large, population-based samples, anxious arousal consistently predicted flatter DCS, higher CRP and IL-6, and lower LF-HRV, whereas anhedonia showed weaker and less consistent associations. Exploratory analyses using the Center for Epidemiologic Studies Depression Scale (CES-D), a widely used depression measure that also captures general distress and anxiety, replicated findings linking depression to biomarker dysregulation. However, the MASQ findings suggest that these effects appeared to be primarily driven by anxiety-related arousal symptoms when symptom dimensions were separated into clusters that were specific to anxiety versus depression. These findings indicate that there is overlooked nuance in research linking depression with cortisol, inflammation, and heart rate variability. Depression measures might be confounded with anxiety symptoms, and the anxious arousal symptom cluster might be particularly strongly related to specific markers of chronic stress.</p>