Exploring Associations between C-Reactive Protein and Self-Reported Interoception in Major Depressive Disorder: A...

Area of Science:

• Neuroscience
• Psychiatry
• Immunology

Background:

• Major depressive disorder (MDD) is characterized by disrupted self-awareness of bodily states (interoception) and heightened systemic inflammation.
• Both interoceptive dysfunction and inflammation are implicated in poor treatment outcomes for MDD.
• Understanding the link between inflammation and interoception is crucial for elucidating MDD pathophysiology.

Purpose of the Study:

• To investigate the association between C-reactive protein (CRP), a marker of systemic inflammation, and self-reported interoception in individuals with MDD.
• To replicate findings on the relationship between depression severity, fatigue, and CRP levels.
• To explore the potential role of inflammation in the pathophysiology of interoceptive impairments in MDD.

Main Methods:

• Ninety-seven individuals diagnosed with MDD completed self-report questionnaires assessing interoception (MAIA-2), depression (BDI-II), and fatigue (MFI).
• Serum C-reactive protein (CRP) concentrations were quantified using a particle-enhanced turbidimetric immunoassay.
• Bayesian inference with Markov Chain Monte Carlo (MCMC) sampling was employed to analyze associations and compute Bayes factors (BF10) for evidence.

Main Results:

• Bivariate analyses revealed minimal evidence for associations between CRP and most dimensions of self-reported interoception (BF10 ≤ 0.32).
• Significant positive correlations were observed between CRP and overall depression severity (r = 0.21, BF10 = 3.19), physical fatigue (r = 0.28, BF10 = 20.64), and reduced activity (r = 0.22, BF10 = 4.67).
• Multivariate analysis indicated moderate evidence that low-grade inflammation (CRP) predicted higher scores on the MAIA-2 Not-Worrying scale (β = 0.28, BF10 = 3.97), even after controlling for confounders.

Conclusions:

• Systemic inflammation, as indicated by CRP, may not be a primary driver of dysfunctional self-reported interoception in MDD.
• Low-grade inflammation might offer a protective effect against excessive worry related to bodily sensations in some individuals with MDD.
• Further research using additional inflammatory biomarkers is needed to definitively rule out immunological involvement in interoceptive impairments.