Relationship between CRP and depression: A genetically sensitive study in Sri Lanka

Background: Previous studies have shown associations between major depression and C-reactive protein (CRP) levels. Few studies have considered the extent to which shared genetic and environmental factors contribute to this association, nor have they considered the relationship outside of European populations. We examined the association between CRP levels and depression and their aetiology in a Sri Lankan population. Methods: Data were collected from 2577 twins and 899 singletons in Colombo, Sri Lanka. Depression symptoms were assessed using the revised Beck Depression Inventory (BDI-II). High-sensitive CRP blood levels were assessed using immunoturbidimetry. Linear regressions were performed to test the association between CRP and depression. The heritability of CRP levels was estimated using Structural Equation Modelling. Results: CRP was significantly associated with BMI (p < 0.01) but not depression (p > 0.05). In males, variance in CRP levels was explained by shared environment (51% 95%CIs: 13-62) and non-shared environment (45% 95% CIs: 36-54). In contrast, in females, CRP variance was explained by genetic (41% 95%CIs: 10-52) and non-shared environment (56% 95%CIs: 47-67). A genetic correlation between CRP and BMI was observed in females only. Limitations: CRP level was based on a single data collection point, longer term data collection would give a more accurate picture of an individual's state of inflammation. Conclusions: The lack of association between depression and CRP strengthens the hypothesis that inflammation might contribute to the development of some, but not all types of depression. CRP levels were moderated by the environment, suggesting interventions aimed at reducing CRP levels and risk for inflammatory conditions, particularly in males.

Automated summary

This study examined the relationship between CRP levels and depression in a Sri Lankan population and found that CRP was significantly associated with BMI but not with depression. The variance in CRP levels was influenced by shared environment and non-shared environment in males, while it was influenced by genetic factors and non-shared environment in females. The lack of association between depression and CRP suggests that inflammation may play a role in the development of certain types of depression, and interventions to reduce CRP levels and inflammation risk may be particularly effective in males.