A slight shaking of the hands, a growing stiffness in the limbs – the symptoms of Parkinson’s disease are treacherous, often mistaken for the normal effects of aging.
Though the aging process and the advancement of the disease are different, Dr. Jim Bennett believes the two may be related. “In one sense, the disease may represent a premature aging of the nervous system,” said Bennett, director of the University of Virginia’s Center for the Study of Neurodegenerative Diseases.
In a recent study, Bennett found that patients with Parkinson’s had 50 percent more damage to a protein complex of their brain cells’ mitochondria, the cellular components responsible for turning food and oxygen into energy. The chemical culprits responsible for the damage are oxygen free radicals.
The free radicals are oxygen molecules that have absorbed an extra electron, making them unstable. “They form something called superoxide,” Bennett said. “There are estimates that you make eight liters of superoxide gas a day.”
Usually, the body is able to safely handle the free radicals, and convert them back into regular oxygen or water. But over time, people can lose that ability and the free radicals build up, potentially causing damage to proteins, DNA strands and other components of a cell.
“In aging, what happens over time is the rate at which you produce oxygen free radicals exceeds the rate at which you can detoxify them,” Bennett said. And for some reason, he said, people with Parkinson’s have more damage from free radicals in their neuronal mitochondria than others.
Bennett doesn’t know if the damage causes Parkinson’s to develop in patients, or if it is just an interesting phenomenon that is happening simultaneously as the disease progresses.
Either way, he doesn’t believe that a cure lies in drinking gallons of cranberry juice or green tea to imbibe as many antioxidants as possible. “But maybe we should be testing those antioxidant compounds as possible drugs,” he said.
Robin Elliott, who is the executive director of the Parkinson’s Disease Foundation and is familiar with Bennett’s work, said there are numerous theories as to what causes the disease, oxidative stress being one of them. He added that doctors are also trying to determine how to best manage the disease until more information is found on how to stop it or even prevent it.
During the disease, the brain cells responsible for producing the chemical dopamine die, leaving patients unable to control their movements. Symptoms often include tremors, stiffness and poor balance. “It causes digestive problems, fatigue, depression, sadness, anxiety, dementia – it is in many ways a full body disease,” Elliott said.
Approximately 1 million Americans have Parkinson’s and it is believed that many more are undiagnosed, according to the foundation.
Although the disease most commonly affects seniors, it strikes people “when they are in the prime of life,” Elliott said. “It’s not just a sad thing that happens to some older people; it’s a bad thing that happens to a lot of people.”
Bennett hopes that as he learns more about the role oxygen free radicals play in the progression of the disease, he can begin to test a drug that would absorb the free radicals in the neuronal mitochondria and stop the damage they cause.
He also hopes to develop a way to test mitochondrial damage in other tissues or cells, such as in blood platelets, to come up with an earlier way to test for Parkinson’s. The disease can only be diagnosed currently when symptoms begin to appear, which Elliott said occurs after 70 percent to 80 percent of the dopamine cells have already been lost.
Both Bennett and Elliott recognize that a cure is a long way off, but are hopeful about the continuing advancements in treatment and knowledge.
“Science is incremental – you don’t wake up with a eureka moment,” Bennett said. “This study says we’re probably on the right track. We’re not going down a blind alley.”
Contact Sarah Barry at (434) 978-7266 or sbarry@dailyprogress.com.
