Symposia
Health Psychology / Behavioral Medicine - Adult
Nur Hani Zainal, M.S.
Graduate Student
Massachusetts General Hospital
Somerville, Massachusetts
Michelle G. Newman, Ph.D.
Professor
Penn State University
University Park, Pennsylvania
Background: The cytokine theory of depression proposes that increased baseline inflammatory activity may accumulate over time and lead to future major depressive disorder (MDD). Building on this theory, the social signal transduction theory of depression (Slavich & Irwin, 2014) and its extension, the social safety theory (Slavich, 2020), propose that the inflammation–future MDD connection is stronger among subgroups with heightened biopsychosocial vulnerabilities (Majd et al., 2020). However, most research conducted on this topic has been cross-sectional and examined between- (vs. within-) persons and symptom severity (vs. diagnosis). Therefore, we tested if elevated inflammatory activity at Time 1 (T1) would predict future within-person 9-year change in MDD diagnosis, and if various psychosocial vulnerabilities moderated these relations.
Method: Community-dwelling adults (n = 945) participated in the Midlife Development in the United States (MIDUS) study. T1 and Time 2 (T2) MDD status was assessed using the Composite International Diagnostic Interview–Short Form, and markers of inflammatory activity at T1 were measured (i.e., levels of serum interleukin-6 [IL-6], C-reactive protein [CRP], fibrinogen). Latent change score modeling was conducted.
Results: Higher T1 IL-6, CRP, and fibrinogen levels of inflammatory activity predicted T1–T2 development/relapse of MDD within persons (d = .159). This effect occurred more strongly among women (vs. men; d = .149 vs. .042), younger (vs. older) adults (d = .137 vs. .119), persons with more (vs. less) chronic health issues (d = .133 vs. .065), low- (vs. middle- or high-) income (d = .161 vs. .050), and persons with more (vs. less) frequent childhood trauma (d = .156 vs. .017).
Conclusion: Findings aligned with expanded cytokine theories, which posit that the impact of increased T1 inflammatory activity on future change in MDD status will be larger for subgroups vulnerable to increased stress exposure. Cognitive–behavioral or pharmacological approaches to reduce inflammatory activity may prevent development/relapse of MDD. This may be achieved through alterations in diet and nutrition (e.g., N-acetyl-d-cysteine, omega-3 supplementation) and lifestyle (e.g., mindfulness meditation, cognitive–behavioral strategies, yoga, exercise; Dutcher et al., 2021). Further, tailoring treatment based on inflammation profiles may be beneficial as elevated markers of inflammatory activity can impede optimal therapeutic response (Carvalho et al., 2013).