New Delhi: The good news: Healthy behaviour appears to slash the risk of coronary disease in people at high genetic risk for events. The bad news: Folks with "good genes" cant expect their genetic makeup to offset bad habits, warns a senior cardiologist here.
Basically, it means that the foundation for prevention has to be lifestyle, because it makes a difference regardless of your genetic risk factor. If you were at high genetic risk, you are not fated to have the problem. Lifestyle is important regardless of whether your genetic risk is high or low, says Dr (Col) Anil Dhall, Director of Cardiovascular Sciences at Venkateshwar Hospital here.
While genetics are important, modification by lifestyle changes, diet and environmental influences can be effected and remains critical, observes Dhall citing recent research done in the US.
Researchers from Massachussets General Hospital, in Boston, used their previously developed "polygenic score" -- derived from a combination of 50 genetic polymorphisms -- to quantify the genetic risk of coronary artery disease across four cohorts for a total of 55,685 subjects.
A "healthy lifestyle score" was then applied to the same participants, derived from information on current smoking, weight, physical activity, and diet. Those with a score of 3 or 4 (with one point each for not smoking, not being obese, being physically active at least one day per week, and eating a healthy diet) were deemed to follow a favourable lifestyle.
Confirming the validity of the polygenic score, the risk of incident coronary events was 91 per cent higher among subjects in the highest quintile as compared with those in the lowest. Likewise, subjects with a lifestyle score of 3 or 4 also had a substantially lower risk for coronary events than those with a score of zero or 1.
Healthy behaviours appear to have a profound effect in mitigating genetic risk. Indeed, across all levels of genetic risk, a favourable lifestyle appeared to cut the likelihood of coronary events roughly in half. So for patients at high genetic risk, those engaging in a healthy lifestyle saw their risk fall by 46 per cent -- a finding seen across cohorts.
Many people equate DNA with destiny, and feel that they don't have control if it is DNA-based risk. The question was, if you are at high genetic risk for heart attack, can we offset that risk by being ideal in terms of lifestyle? The answer is a firm yes, asserts Dhall.
Importantly, this is really a yin-yang relationship. You can think of it another way as well, which is if you have bad genes and a favourable lifestyle, your 10-year risk was five per cent.
But what if you have good genes and a very unfavourable lifestyle? It turns out you can basically really offset a good hand that you've been dealt by practising unfavourable lifestyle. So basically, bad genes/favourable lifestyle is approximately equal to good genes/unfavourable lifestyle.
The polygenic risk score used in the study is not yet commercially available. But the point made by the new research is that people do not need a genetic score to know whether or not they should be adopting a healthy lifestyle. "Everybody should practice a good lifestyle," said Dhall.