A recent cross-sectional analysis of two populations of 73,131 adults between 20 and 100 years old revealed a link between C-reactive protein (CRP), a protein present once inflammation occurs, levels and distress or depression. Although the pathogenesis was not fully explained, a positive correlation between CRP and depression was found in this study.
Researchers of Copenhagen, Denmark split participants into three groups, self-reported anti-depressant use, prescription record anti-depressant use, and hospitalization due to depression, and asked them to respond to three questions:
– Do you have the feeling that you have not accomplished very much recently?
– Do you feel like giving up?
– Do you often feel nervous or stressed?
The final question was unrelated to depression and used as a negative control. CRP levels were measured in each participant and four categories of CRP were made (≤1 mg/L, 1.01-3.0 mg/L, 3.01-10.0 mg/L, and >10.0 mg/L). Of the categories, high CRP levels were associated with higher risk of distress and depression based on the answers given to the aforementioned questions. Specifically, the three groups of depression participants had the following CRP odds ratios:
– Self-reported antidepressant use: 1.38 (CRP 1.01-3.0), 2.02 (CRP 3.01-10), 2.70 (CRP > 10.0)
– Prescription antidepressant: 1.08, 1.47, 1.77
– Depression linked hospitalization: 1.30, 1.94, 2.27
The results showed that higher levels of CRP were associated with higher risk of depression and psychological distress.
Does depression cause increased inflammation, or is depression more likely in those with higher CRP levels? Further research is needed to know the causal relationship, however, this study puts forward CRP as a target of interest for depression attenuation.
Marie Kim Wium-Andersen, David Dynnes Ørsted, Sune Fallgaard Nielsen, Børge Grønne Nordestgaard. 2012. Elevated C-Reactive Protein Levels, Psychological Distress, and Depression in 73 131 Individuals. Arch Gen Psychiatry.