Cumulative Depression Episodes Predict Later C-Reactive Protein Levels: A Prospective Analysis

• Type of Material: Article
• Authors: William E. Copeland, Duke University; Lilly Shanahan, University of North Carolina at Greensboro; Carol Worthman, Emory University; Adrian Angold, Duke University; E. Jane Costello, Duke University
• Language: English
• Date: 2012-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.biopsych.2011.09.023
• Title of Journal or Parent Work: Biological Psychiatry
• ISSN: 0006-3223
• Volume: 71
• Issue: 1
• Start Page: 15
• End Page: 21
• Grant/Funding Information: The work presented here was supported by the National Institute of Mental Health (MH63970, MH63671, MH48085), the National Institute on Drug Abuse (DA/MH11301), NARSAD (Early Career Award to First Author), and the William T. Grant Foundation.
• Keywords: Depression; CRP; Adolescence; Inflammation; Epidemiology; Childhood
• Research Categories: Health Sciences, Mental Health; Psychology, Psychobiology; Health Sciences, Epidemiology

Abstract

Background: Depression is associated with elevated levels of the inflammation marker C -reactive protein (CRP), yet the direction of this association remains unclear. This study tested bi-directional longitudinal associations between CRP and depression in a sample of adolescent and young adults. The study compared the effects of current depression to the cumulative episodes of depression over time. Methods: Nine waves of data from the prospective population-based Great Smoky Mountains Study (N = 1,420) were used, covering children in the community aged 9–16, 19, and 21 years old. Structured interviews were used to assess depressive symptoms, depression diagnosis, and cumulative depressive episodes. Bloodspots were collected at each observation and assayed for CRP levels. Results: CRP levels were not associated with later depression status. In contrast, all depression-related variables displayed evidence of association with later CRP levels. The associations with depressive symptoms and diagnostic status were attenuated after controlling for covariates particularly body mass index, smoking, and medication use. The effect of cumulative depressive episodes, however, continued to be significant after accounting for a range of covariates. Body mass index, smoking behavior and recent infections may mediate a portion of the effect of cumulative episodes on later CRP, but cumulative depressive episodes continued to predict CRP levels independently. Conclusions: The occurrence of multiple depressive episodes exerted the greatest effect on later CRP levels. This suggests that risk for the diseases of middle age - cardiovascular and metabolic disease – may begin in childhood and depend, in part, upon long-term emotional functioning.