Life live, live long

While living life as a thrill seeking extrovert may land some people in trouble, other dare devils might be genetically primed to live into their 90s or longer, a new study reveals.

A variation of a much studied gene involved in transmission of dopamine, a key component of the brain’s reward and learning system, was found to be far more frequent among the very old. The same variant was also linked to longer life in mice.

However, Professor Robert Moyzis, of the University of California, Irvine, said the variant might not extend lifespan directly. Instead, it appears to predispose those who bear it to a more vigorous lifestyle.

“This particular variation has already been associated with personality traits that are much more outgoing, much more socially engaged,” Professor Moyzis said.

“We think it’s a simple as that. Obviously, if you are much more likely to be engaged in physical and intellectual activities as you age, there have been many studies that have shown that is a good predictor of adding a few more years to your life.”

The human subjects in the study came from Laguna Woods, part of a group involved in the Leisure World Cohort Study that began in 1981. It included people who were 90 years or older in 2003.

While most have since passed away, their genes, as well as cell lines, live on, perpetuated in laboratories so they will be available for research.

In this study, genetic samples from 310 people 90 years old or older were checked for the gene variant, known as the DRD4 7R allele. Sixty six per cent more people possessed the variant in the 90 plus group when compared with a control group of nearly 3,000, aged seven to 45 years.

For the mouse component, researchers at Brookhaven National Laboratory found mice that had the gene variant ‘knocked out’ of their DNA had their lifespans decreased by 7% to 9.7% compared with mice that carried it.

“Even in a fairly enriched environment, you take out this gene and the mice just don’t live very long,” Professor Moyzis said.

While the gene variant appears to promote long life, it also has been associated with high risk behaviour, drug addiction and attention deficit hyperactivity disorder, or ADHD – though children with the variant might not properly belong under the broad umbrella of ADHD.

The discovery of the gene variant’s association with longevity might inspire people to become more active as they age, potentially extending their lives – even if they don’t harbor the variant themselves.