Global DNA methylation in old subjects is correlated with frailty.

Epigenetic variations have been widely described to occur during the aging process. To verify if these modifications are correlated with the inter-individual phenotypic variability of elderly people, we searched for a correlation between global DNA methylation levels and frailty. We found that the global DNA methylation levels were correlated to the frailty status in middle/advanced-aged subjects but not with age. A 7-year follow-up study also revealed that a worsening in the frailty status was associated to a significant decrease in the global DNA methylation levels. These results suggest that the relaxation of the epigenetic control in aging is specifically associated with the functional decline rather than with the chronological age of individuals. Thus, the modifications of DNA methylation, representing a drawbridge between the genetic and the environmental factors affecting the age-related decay of the organism, may play an important role in determining physiological changes over old age.