Genetic clues to healthy ageing

Scientists believe people who live to 100 years or more hold valuable secrets in their genes that can reveal targets for medicines to tackle a wide range of age-related diseases, as well as improving longevity itself.

“If you make it to 100, you must have had good health-otherwise you wouldn’t be at the tail end of the age distribution curve,” Kaare Christensen of the Danish Ageing Research Centre said. “So basically, we’re trying to figure out how they do it.”

Of course, genes are not the whole story: experts believe genetic factors account for a only fraction of longevity. Other factors like a healthy lifestyle, good diet and safe environment combine to play a role in determining when we die.

Yet so-called “longevity genes” certainly exist, and their importance grows the longer a person lives, so identifying them and finding out what they do to fight off killer diseases is a hot area of research.

With lifespans already increasing at a breathtaking rate — an average of three months is being added to life expectancy every year at the moment — scientists stress that a “magic pill” to help people live ever longer is not what anyone should be seeking.

Instead the aim is known as “compression of morbidity”-improving the health of rapidly ageing populations and squeezing to a minimum the amount of time at the end of their lives when they are sick, in pain, or dependent.

Genetic science and technology is developing rapidly too, allowing scientists to scan the genes of the super-old in search of the secrets of long life-and drugs to mimic them are starting to appear. Until recently, only one candidate had shown any promise as a potential “longevity gene”.

It is known as APOE. On the one hand, its variants have been linked with an increased risk of heart disease and of developing the brain-wasting disease, Alzheimer’s. On the other, it is associated with a greater chance of a longer, healthier life.

Scientists have found that a particular variant known as APOE4, which gives carriers a higher risk of developing Alzheimer’s and heart disease, is about 50 percent less common in centenarians than in younger people. Other “longevity gene” candidates are now starting to emerge, including one called FOXO3A and another called humanin, both of which have links to the body’s insulin pathways.

With them comes more evidence that genes associated with long life are also linked to decreased risk of major killers like heart disease, Alzheimer’s and diabetes. Nir Barzilai of the Albert Einstein College of Medicine at Yeshiva University in New York has been conducting studies with a group of several hundred centenarians in the United States to see if he can find gene patterns that can be chemically copied.