Higher Lipopolysaccharide Levels Are Linked to Less Anhedonia and Lower Severity of Major Depressive Disorder.
Level 4 - case-series / case-control
Cross-sectional observational study of clinical cohorts
PubMed 42651162 · doi:10.3390/brainsci16080852
What was done
Serum concentrations of lipopolysaccharide (LPS) and cytokines (IL-10, TNF-α, IL-6, IFN-γ) were measured by ELISA in 95 adults with major depressive disorder (mean age 44 ± 14 years) recruited from inpatient and outpatient psychiatric services. Depressive symptom severity was evaluated using the Montgomery-Åsberg Depression Rating Scale (MADRS). Associations between LPS, cytokines, and individual depressive symptom dimensions were evaluated using multivariable linear regression, quantile regression, and mediation analyses adjusting for demographic and clinical covariates.
What was found
Patients with severe depression had significantly lower circulating LPS concentrations compared to those with mild-to-moderate depression (95.6 vs. 165.2 pg/mL, p = 0.007), whereas cytokine levels did not differ significantly between groups. Serum LPS levels were inversely associated with overall depression severity, anhedonia factor scores, and MADRS item 8 ("inability to feel"). Higher LPS concentrations correlated with lower anhedonia, less reduced appetite, less lassitude, lower inner tension, and lower suicidality, but with higher apparent sadness, concentration difficulties, and reduced sleep. Mediation analysis showed that anhedonia mediated the inverse relationship between LPS and overall depression severity.
Why it matters
These findings suggest that systemic endotoxin exposure may track with specific symptom profiles and biological subgroups rather than straightforwardly worsening overall depression severity.
Limits
The sample size was modest (n = 95) with no healthy control group included. The cross-sectional design cannot establish causality or temporal direction between endotoxin levels and specific depressive symptoms.
Cited by
- context Research demonstrates significantly higher circulating levels of LPS (lipopolysaccharide) in individuals with major depressive disorder compared to those without the condition.