Biological clocks and physical functioning in monozygotic female twins

Area of Science:

• Gerontology
• Epigenetics
• Biomarkers of Aging

Background:

• DNA methylation age (DNAm age) and leukocyte telomere length (LTL) are key biomarkers of biological aging, correlating with chronological age.
• The association between these cellular aging markers and physical function, such as muscle strength, remains unclear.
• Physical capacity declines with age and is linked to mortality, highlighting the need to understand aging biomarkers' impact.

Purpose of the Study:

• To investigate the association between DNAm age and LTL with body composition and physical functioning.
• To examine these relationships in a cohort of monozygotic twin sisters to control for genetic factors.

Main Methods:

• DNAm age was calculated from methylation data, with age acceleration defined as residuals from DNAm age vs. chronological age regression.
• Leukocyte telomere length (LTL) was measured using qPCR.
• Body composition (fat, lean mass) and physical functioning (grip strength, knee extension strength, walking speed) were assessed.

Main Results:

• Participants' DNAm age was lower than their chronological age.
• Accelerated epigenetic aging (higher age acceleration) was significantly associated with lower grip strength (p=0.011).
• LTL and other physical functioning measures showed no significant association with DNAm age or its acceleration.

Conclusions:

• Accelerated DNAm age is associated with reduced grip strength, a predictor of functional decline and mortality.
• Epigenetic aging may play a role in age-related muscle strength decline.
• Further research is needed to clarify if epigenetic aging causally influences muscle strength or merely reflects aging processes.