Epigenetic clocks serve as biomarkers for biological age, yet their underlying biological mechanisms remain poorly understood. This study investigates the role of blood cell composition in influencing DNA methylation age and age acceleration, utilizing a principal component analysis (PCA) method that addresses the collinearity of blood cell counts.
What this study does not show
This research does not establish a direct causal relationship between blood cell composition and health outcomes, nor does it provide definitive evidence that modifying blood cell composition will influence biological age or health outcomes.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Partial
- Clinical utility: Not established
The study analyzed data from 4,058 samples to quantify the contribution of blood cell composition to DNA methylation age and age acceleration, revealing that up to 53% of the variation in DNA methylation age can be attributed to cell counts, particularly the balance between naïve and memory T cells. In contrast, associations between age acceleration and cell counts explained up to 21% of the variance, primarily involving neutrophils.
Furthermore, the study examined the influence of cell composition on the relationship between age acceleration and 176 incident health outcomes in a larger cohort of 18,859 individuals. The findings indicate that while cell composition significantly attenuates the association of age acceleration with health outcomes, this effect remains modest.
Overall, the research suggests that DNA methylation age and age acceleration reflect different biological processes, with blood cell composition playing a notable role in the former. However, the contribution of blood cell composition to age acceleration’s association with mortality and disease outcomes appears limited.
Conclusion
This study enhances our understanding of the biological interpretations of DNA methylation age and age acceleration, emphasizing the importance of blood cell composition in these processes. Future research may further elucidate the implications of these findings for health outcomes and aging.