Inflammatory biomarkers may pinpoint people at high-risk of psychiatric disorders

Inflammatory biomarkers such as leukocytes, haptoglobin, C-reactive protein (CRP), and immunoglobulin G (IgG) appear to be associated with a subsequent risk of psychiatric disorders and may thus aid in identifying high-risk populations, according to a study.

Researchers evaluated potential association between inflammatory biomarkers and any psychiatric disorders (ie, depression, anxiety, and stress-related disorders) in a prospective cohort including 585,279 individuals (mean age 45.5 years, 52.4 percent male) from the Swedish Apolipoprotein Mortality Risk (AMORIS) study. These participants had no prior psychiatric diagnoses and had an available measurement of at least one inflammatory biomarker. The associations were then validated using data from the UK Biobank.

A nested case-control study was performed to visualize the longitudinal trajectories of the studied biomarkers before diagnosis of psychiatric disorders in the AMORIS cohort. Additionally, genetic correlation and Mendelian randomization (MR) analyses were conducted in order to identify the genetic overlap and causality of the studied associations using publicly available GWAS summary statistics.

In the AMORIS cohort, the risk of any psychiatric disorders was high among individuals with a higher-than-median level of leukocytes (hazard ratio [HR], 1.11, 95 percent confidence interval [CI], 1.09–1.14), haptoglobin (HR, 1.13, 95 percent CI, 1.12–1.14), or CRP (HR, 1.02, 95 percent CI, 1.00–1.04). Conversely, the risk was lower among individuals with higher IgG level (HR, 0.92, 95 percent CI, 0.89–0.94).

The associations were consistently observed for depression, anxiety, and stress-related disorders and were largely validated in the UK Biobank cohort (n=485,620).

Analyses of trajectories indicated that individuals with vs without psychiatric disorders had higher levels of leukocytes and haptoglobin and a lower level of IgG up to 30 years before the diagnosis. A possible causal association between leukocytes and depression was found on MR analysis.