It’s a well-established fact that smoking is terrible for you, even in small amounts. When it comes to wholly preventable risk factors for a host of serious diseases, smoking cigarettes is right at the top of the list.
And yet we all know someone who seemed to live forever despite smoking like a chimney every day of his or her adult life.
What is it about these individuals that allow them to stave off the damage cigarettes usually wreak on the human body? Is there something innate that keeps them healthy longer than other smokers who suffer from smoking-related diseases like cancer?
A new study published in the Journals of Gerontology, Series A explores these questions. In particular, the authors investigate whether there are genetic markers that might indicate which people are more likely to have a predisposition to longevity. And they looked in long-lived smokers to find them.
Researchers from UCLA and University of Southern California (USC) took a group of smokers who had lived to 80 or older despite maintaining the habit, and compared them both to non-smokers their own age and current smokers who were younger. They found both groups of older individuals were comparable in terms of their mortality, as well as their signs of disease such as markers of inflammation on blood tests. This was in contrast to the group of younger smokers, who had higher rates of mortality compared to other people their own age, and already showed signs of worse physiological functioning. The majority of the younger smoking group was not predicted to live as long as the older smokers.
By performing genetic analysis on the older smoking group and comparing them to younger subjects, the authors identified a collection of genetic sequences that together functioned within a network. Using those sequences, they calculated a risk score based on how many a given individual had. They found that those individuals who had a greater number were significantly more likely than their peers to live into advanced old age, as well as having a lower prevalence of cancer.
The specific role these genes might play in sustaining longevity weren’t part of the new study. The authors speculate that they may code for functions that repair cellular damage from environmental factors. They note that smoking has a damaging effect on the integrity of a person’s DNA, and that instability within an individual’s genome is one of the factors that contributes to the development of cancer. The genetic sequences identified in healthy older smokers may have a protective effect, which is why they have survived despite the significant ill effects of their habit.
As with all studies, it’s important not to jump to any huge conclusions from any given article. There are likely to be many, many genetic factors that contribute to the aging process, of which these may be only a few. This report shows as association between a set of genetic sequences and living a long time, but more study is needed to determine how to look for other genetic markers, which may play as large a role or larger in a person’s longevity and ability to fight the damage that comes with aging. There is still a lot to learn about how genes interact with each other, and what those interactions specifically accomplish within the human body.
However, as the authors state quite plainly, “aging is the number one risk factor for mortality among humans.” It’s a process we all face, preventable only by the unpalatable alternative of dying young. Understanding the processes that contribute to our bodies’ infirmity as we get older may help prevent or forestall them. This study offers clues that can point further research in the right direction.