Inflammation and specific symptoms of depression: cross-sectional sex-specific associations between C-reactive protein and symptoms of depression in the Lifelines Cohort Study
TL;DR
Findings support an inflammatory phenotype of depression characterized by anhedonia, fatigue, and sleep disturbance, and suggest that men who exhibit high levels of inflammation may be at increased risk for SIB.
Abstract
Increasing evidence suggests that systemic inflammation may be associated with specific depressive symptoms, though potential sex differences remain unclear. This study investigated whether elevated levels of systemic inflammation were associated with the endorsement of specific depressive symptoms among depressed individuals and whether these associations differed by sex. Participants (n=52,781; 59.14% female) aged 44.42 years (SD = 12.15) who completed the Mini International Neuropsychiatric Interview (MINI) and who had systemic inflammation indexed via circulating C-reactive protein (CRP) at the baseline assessment of the population-based Lifelines Cohort Study were examined. Those who screened into the depression module of the MINI (n=2,799) were included in analyses examining whether the likelihood of endorsing specific symptoms of depression differed for those with higher (CRP ≥ 2mg/L) and lower levels of CRP (CRP < 2mg/L) using logistic regression. Moderation analyses tested whether associations between CRP and depressive symptoms differed by sex. Individuals with elevated CRP were more likely to endorse specific depressive symptoms, including anhedonia (OR = 1.31, p = .002), sleep disturbances (OR = 1.26, p = .003), and fatigue (OR = 1.37, p < .0001) compared to those with low levels of inflammation. The only sex-based difference observed was that men with elevated inflammation were more likely to endorse suicidal ideation/behavior (SIB) than women with elevated inflammation (OR = 1.82, p = .02). No associations between inflammation and depression symptoms were observed among women. These findings support an inflammatory phenotype of depression characterized by anhedonia, fatigue, and sleep disturbance. It also provides preliminary evidence to suggest that men who exhibit high levels of inflammation may be at increased risk for SIB, highlighting a need for additional research on this clinically important subject.