While low-grade inflammation has consistently been observed in subjects with depression, studies on the possible relationship between inflammation and other aspects of brain function are as yet sparse. In this study, we aimed to investigate the possible association between serum levels of the inflammation marker C-reactive protein (CRP) and personality traits.
In this study, serum levels of high-sensitivity CRP were determined by ELISA in a population of 270 42-year-old women recruited from the population registry who had been assessed using the Temperament and Character Inventory. Self-reported previous or ongoing depression was also recorded. Unpaired two-tailed t-tests were used for comparison between two groups and correlations were evaluated by the calculation of Pearson's r-coefficient.
The temperament trait harm avoidance was positively (r = 0.227, p < 0.05) and the character trait self-directedness was negatively (r = -0.261, p < 0.01) associated with serum levels of CRP (p-values corrected for multiple comparisons). The correlations between the personality traits and CRP were observed also after exclusion of subjects reporting ongoing depression (n = 26). Whereas women reporting ongoing depression showed significantly increased levels of CRP as compared to non-depressed women (n = 155), women reporting a history of depression displayed no significant difference in CRP levels as compared to women that reported that they had never been depressed.
Serum levels of CRP in women was found to be associated with the personality traits harm avoidance and self-directedness. In addition, moderately elevated levels may be a state dependent marker of depression.