The Mediating Role of Daily Affect Dynamics in Bidirectional and Longitudinal Associations Between Depressive...

Extensive research has established relationships between depression and inflammation, yet greater attention is needed to elucidate mechanisms through which these processes unfold across multiple levels of analysis and time scales. This cohort panel study evaluated the role of daily affect dynamics in bidirectional and longitudinal associations between depressive symptoms and inflammation.

Using data from the second and third waves of the Midlife in the United States (MIDUS) study, the sample included 563 adults (M age =52.4; 57% female; 84% White). During the Biomarker Project, depressive symptoms were assessed at a single time point using the CESD-20, and the inflammatory markers were collected, including CRP and 4 cytokines (IL-6, IL-8, TNFα, IL-10). During the Daily Diary Project, daily affect and stress were measured over 8 consecutive days. Two affect dynamics indicators were specified: affective variability and reactivity to daily stressors. Multilevel structural equation models simultaneously tested autoregressive and cross-lagged associations between depressive symptoms and inflammation at the person-level, and day-level mediated paths involving daily affect dynamics.

Results revealed that affective variability and reactivity mediated the autoregressive paths of depressive symptoms across 2 waves. Positive affective variability mediated the pathway from heightened baseline depressive symptoms to higher CRP levels at follow-up. Negative affective reactivity to daily stressors mediated the pathway from higher baseline CRP to subsequent depressive symptoms.

Findings suggest daily affective processes as potential mechanisms linking depressive symptoms and inflammation, underscoring the significance of promoting affective stability and adaptive stress responses in everyday life.