Inflammatory markers and incident depression: Evidence in a population-based prospective study

Area of Science:

• Gerontology
• Psychiatry
• Immunology

Background:

• The link between pro-inflammatory cytokines and depression is recognized.
• Longitudinal evidence demonstrating causality is limited.

Purpose of the Study:

• To investigate the longitudinal association between inflammatory markers and depression in older adults.
• To explore the predictive value of specific inflammatory markers for incident depression.

Main Methods:

• Analysis of a community-based sample of 2761 older adults (ages 55-98) from the Singapore Longitudinal Ageing Study (SLAS).
• Assessment of baseline and follow-up data on inflammatory markers (CRP, IL-6, TNFα, inflammation risk score) and depression.
• Longitudinal regression models controlling for sociodemographic, lifestyle, and medical confounders.

Main Results:

• Cross-sectional analysis revealed significant associations between CRP, IL-6, and TNFα with depression at baseline.
• Longitudinal analysis indicated that IL-6, TNFα, and inflammation risk score predicted elevated depression risk at follow-ups.
• No significant association was found between CRP and subsequent depression after adjusting for confounders.

Conclusions:

• Inflammation, particularly IL-6 and TNFα, is a significant predictor of depression in older adults.
• Heterogeneous findings in prior research may stem from variations in study populations, depression definitions, inflammatory markers, and confounder adjustment.
• This study underscores the importance of considering inflammatory processes in the development of depression among the elderly.