Unipolar depression has been found to associate with elevated C-reactive protein levels (CRP) in men, but findings among women have been conflicting. It has been hypothesized that this would be explained by a different hormonal environment (compared with men) and its changes throughout the lifecycle in women, but until now, the corresponding evidence has been lacking. We investigated the association between depressive symptoms and CRP levels in a population-based study in pre-, peri- and postmenopausal women, and also, whether this association is affected by the use of exogenous hormones (contraceptives and postmenopausal hormone therapy).
Initially, the entire age classes of those born in 1942, 1947, 1952, 1957 and 1962, and living in Pieksämäki, Finland were invited (N=1,294), and out of 730 women 512 (70.1 %) participated in this cross-sectional study in 1997-98. Depressive symptoms were assessed by Beck's Depression Inventory -21 (BDI-21) and C-reactive protein (CRP) was measured with a high-sensitivity CRP assay (hs-CRP).
We found a statistically significant positive correlation between hs-CRP-levels and depressive symptoms in peri- and postmenopausal women not using exogenous hormones (Spearman partial correlation coefficient, r=0.189, p=0.011; and r=0.436, p=0.033, respectively). On the contrary, no significant correlations were found in peri- and postmenopausal women using exogenous hormones, or in premenopausal women irrespective of their exogenous hormone use.
Our novel findings strongly suggest that female hormones might have a major impact on the association between elevated CRP levels and depressive symptoms in females. Further studies are, however, needed to confirm our findings.