Smoking, heavy alcohol use are associated with epigenetic signs of aging

Using data from the publicly available Gene Expression Omnibus, Robert A. Philibert, MD, PhD and colleagues at the University of Iowa and other institutions analyzed patterns of DNA methylation, a molecular modification to DNA that affects when and how strongly a gene is expressed. Prior research had shown that methylation patterns change in predictable ways as people age, as well as in response to environmental exposures, such as cigarette smoke and alcohol. In these earlier studies, Dr. Philibert's laboratory identified two specific locations in the genome, base pairs cg05575921 on the AHRR gene and cg23193759 on chromosome 10, at which methylation levels were highly associated with smoking and alcohol consumption, respectively. In fact, they showed, DNA methylation levels at these two locations was a better measure of substance use than people's self-reported estimates. Thus, in this follow-up study, Meeshanthini Dogan, MS, and Dr. Philibert used methylation levels as a proxy for tobacco and alcohol consumption. They estimated each person's biological age using a previously validated epigenetic "clock" based on methylation levels at 71 locations in the genome, as measured by the widely used Infinium HumanMethylation450 BeadChip. Then, they calculated the difference between biological age and chronological age, and assessed the relationship between tobacco and alcohol use and premature aging. They found that all levels of exposure to smoke were associated with significantly premature aging. Science Daily