Frailty factor: How well you walk when you’re older may depend on one gene

PITTSBURGH, Pa. — Losing mobility and becoming more frail is a common issue for many older adults. While many seniors try to keep frailty at bay through diet and exercise, a study finds who does and doesn’t become infirm may come down to one gene. Researchers from the University of Pittsburgh Graduate School of Public Health say a gene controlling dopamine levels in the brain can dictate how well an elderly person walks as they age.

“Most people think about dopamine’s role in mobility in the context of Parkinson’s disease, but not in normal aging,” says senior author Caterina Rosano in a university release. “We were curious to see if a genetic predisposition to produce more or less dopamine was related to mobility in individuals who had some level of frailty, yet did not have dementia, parkinsonism or any other neurological condition.”

The study reveals a gene called COMT breaks down dopamine to control its levels within the brain. Researchers looked at more than 500 adults over the age of 65, comparing their levels of frailty. This is a common part of the aging process which includes declines in physiological function, poor adjustment to outside stressors, and a tendency to develop other health issues. The study excluded adults who were either on dopamine-related medications or had been diagnosed with Parkinson’s disease.

How frailty is linked to dopamine

Dopamine is a neurotransmitter, sending chemical messages between neurons in the brain. Typically, these messages are part of the body’s “feel good” response when the body is expecting a reward. It also plays a role in several body functions including blood flow, pain processing, and motor control.

Significant drops in the neurotransmitter have been associated with neurological conditions like Parkinson’s. Focusing on COMT and the body’s production of dopamine, researchers examined how varying levels affect seniors without diseases.

“We found that in older, frail adults, those who have a high-dopamine genotype are more likely to maintain a faster gait and may be more resilient to mobility disablement as they age,” Rosano reports.

The Pittsburgh team adds that adults with a high-dopamine COMT gene constitution have walking speeds 10 percent faster than their peers with a low-dopamine COMT genotype.

“This 10% difference may seem small, but it could make a big difference for a person walking across a busy street while negotiating traffic,” Rosano explains. “This difference is even more striking when you consider just how many complex genes influence walking.”

Giving seniors their mobility back

Rosano and her co-authors are working with scientists to determine what amount of dopamine could repair this loss in mobility. Their goal is to one day make it possible for seniors to take dopamine supplements which can fight off frailty.

“There are a lot of individuals living in the community who have dopamine levels toward the lower end of normal who don’t have Parkinson’s disease or psychiatric conditions,” the professor of epidemiology says. “If we give dopamine to these people, could we make them more resilient? That’s what we don’t know yet.”

Until a treatment can be developed, researchers encourage older adults to engage in physical activities which are both fun and challenge the mind. These include dancing and walking with a loved one.

“I love to see grandparents walking around holding hands with their grandchildren because they have to look where they are going, where the child is going, keep an eye on the surroundings and pay attention to what the grandchild is saying, all at the same time. They get an amazing multi-sensory rehab, and it’s fantastic.”

The study appears in the Journal of The American Geriatrics Society.

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