The relationship of C-reactive protein to obesity-related depressive symptoms: a longitudinal study

Abstract

Obesity has been shown to produce a state of systematic low-grade inflammation that may have detrimental neuropsychiatric effects. This study examined longitudinal associations between obesity, inflammation, and depressive symptoms amongst a cohort of older English adults over 4 years of follow-up. Participants were 3891 obese and non-obese people drawn from the English Longitudinal Study of Ageing (ELSA) [aged 64.9 (SD = 8.8) years, 44.6% men]. Depressive symptoms were assessed at baseline and after 4 years of follow-up using the eight-item Centre for Epidemiological Studies - Depression Scale (CES-D). Approximately 26.3% (N = 1 025) of the sample were categorized as obese at baseline. Obesity at baseline was associated with elevated levels of depressive symptoms at follow-up (P less than .001), in analyses that adjusted for depression levels at baseline and sociodemographic and background variables including the prevalence of permanent illness/disability, alcohol consumption, sedentary behavior, and smoking. In addition, C-reactive protein (CRP) concentrations at baseline were independently associated with CES-D depression scores at follow-up (P = .008) in fully adjusted analyses. Subsequent mediation analyses revealed that CRP levels explained approximately 20% of the obesity-related longitudinal change in depression scores. These data suggest that chronic inflammation may be a key determinant of depressive symptoms in obesity.