The relationships between high-sensitivity C-reactive protein and incident depressed mood among older adults

Background. High levels of high-sensitivity C-reactive protein (hs-CRP) are associated with depressed mood, but the causal relationships are not known. Therefore, we examined the relationships between hs-CRP and incident depressed mood among the elderly. Methods. Altogether 764 (69%) individuals out of a representative sample of subjects aged 70 years or older (N = 1113) were screened with the Short Zung Self Rating Depression Scale (SZSRDS), and serum hs-CRP determinations were done at the same time. After a two-and-a-half-year follow-up, the SZSRDS examinations were repeated among those who were free of depressed mood (SZSRDS score >= 28 or use of an anti-depressant drug) at the baseline (N = 404). Analysis of covariance (ANCOVA) and logistic regression were used to analyse the relationship between the baseline hs-CRP (< 1, 1 < 3, 3 < 10 mg/L) and the follow-up SZSRDS scores (10-40) and depressed mood. Results. Baseline hs-CRP was not associated with an increasing trend in SZSRDS scores and depressed mood in the total study population, but there was a significant gender interaction. Among the men, elevated hs-CRP was associated with an increasing trend in the SZSRDS score and depressed mood. Conclusions. High hs-CRP predicts a higher incident SZSRDS score and depressed mood among older men, suggesting a possible inflammatory etiology for depression.