Epigenetic clocks, which serve as biomarkers of biological age, have garnered significant interest in the field of longevity and metabolic health. However, the biological mechanisms underlying these clocks remain poorly understood. This study, published in Genome Medicine, investigates the relationship between blood cell composition and DNA methylation age, as well as age acceleration.
What this study does not show
While the study identifies associations between blood cell composition and DNA methylation metrics, it does not establish direct causation or provide evidence for specific health outcomes resulting from these associations.
The researchers developed a principal component analysis (PCA) method that addresses the collinearity of blood cell counts, allowing for a clearer interpretation of how these factors contribute to DNA methylation age and age acceleration. The study analyzed data from 4,058 samples and examined the influence of cell composition on the association between age acceleration and 176 incident health outcomes in a larger cohort of 18,859 individuals.
Results indicated that up to 53% of the variation in DNA methylation age could be attributed to blood cell counts, particularly the balance between naïve and memory T cells. In contrast, the association between age acceleration and cell counts explained a smaller portion of the variance (up to 21%), with neutrophils playing a significant role in 2nd-generation clocks.
Interestingly, the study found that blood cell composition significantly attenuated the association between age acceleration and various health outcomes, although the effect was described as modest. This suggests that while DNA methylation age and age acceleration are influenced by blood cell composition, their implications for mortality and disease outcomes may be limited.
In conclusion, the findings highlight that DNA methylation age and age acceleration reflect different biological processes, influenced by blood cell composition. This research contributes to the understanding of epigenetic clocks and their potential applications in assessing biological age and health risks.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Partial
- Clinical utility: Not established
The evidence is based on primary research involving human participants.