Scientists are adding about five hours to the average lifespan estimate each day, one expert says. In fact, this is the first time in history the number of older people in the world is growing faster than the number of young people.
Generally speaking, living longer is a good thing. However, our chances of developing a degenerative disease such as Parkinson’s or Alzheimer’s skyrocket as we get older.
“The older you get, the bigger your risk. It doesn’t ever level off,” said Gregory Petsko, professor emeritus of biochemistry and chemistry at Brandeis University and professor of neurology at Weill Cornell Medical College.
Petsko spoke recently on the subject of Parkinson’s disease to an audience of students, teachers and the public at the Oklahoma School of Science and Mathematics.
By 2050, Petsko and other experts predict a global epidemic of Alzheimer’s and Parkinson’s.
“As the population gets older and the number of children gets smaller, the number of people with these diseases increases. We have fewer working people to support them; this gets to be a considerable health problem,” Petsko said.
In the next several decades, Petsko estimates there will be up to 32 million people in the United States over the age of 80. Half will have Alzheimer’s and about 3 million will have Parkinson’s.
“No country is spared. This is a universal human affliction,” he said.
The Shaking Palsy
James Parkinson, for whom the disease was named, dubbed it the Shaking Palsy in his 1817 essay on the disease. He was the first to describe the symptoms but erroneously hypothesized the tremors were caused by lesions in the cervical spinal cord.
About 16,000 to 17,000 Oklahomans live with Parkinson’s disease, according to estimates by the Oklahoma chapter of the American Parkinson’s Disease Association. Oklahoma doesn’t have a registry for Parkinson’s, so the estimate is based on frequency in the country. About 1.5 million Americans have Parkinson’s disease.
Parkinson’s is a nervous system disorder characterized by tremors, progressive muscular degeneration and muscle stiffness that can lead to immobility. Patients have a severe lack of dopamine in their brains, which can also cause depression and anxiety.
Parkinson’s can affect your speech and cause a host of other problems. Most people don’t die from Parkinson’s, but from complications caused by the disease.
Most Parkinson’s cases are random, Petsko said.
But for 10 percent of patients, it’s inherited.
“You shouldn’t worry about that, even if you have a relative or two who has the disease,” Petsko said. “If you were part of this group, you’d know it because practically everyone in your family would get Parkinson’s disease.”
Cases and causes
The disease has many possible triggers.
Michael J. Fox got it young, at age 38. His is a case of bad luck, Petsko said.
Muhammad Ali got it from multiple blows to the brain. Pope John Paul II died of a sporadic late onset of the disease.
Adolf Hitler had Parkinson’s disease. Petsko said Hitler likely would have died from complications six or seven years after he committed suicide had he not done so.
It can be caused by a viral infection of the brain. Exposure to certain poisons can cause it. But the biggest risk is age.
Getting to the root
Alpha-synuclein is a protein in humans that is of great interest to Parkinson’s researchers. When synuclein proteins aggregate into dense fibrils called lewy bodies, they kill neurons and cells. In some lewy bodies, there is a bit of synuclein that is clipped off or fragmented. It turns out, it’s likely this fragment that causes the synuclein to aggregate out of control.
So what enzyme is cutting that fragment? There are more than 500 protein-cutting proteases in the human genome.
Petsko, who is also a yeast geneticist, remembered that yeast cells resemble lewy bodies. When introduced, yeast was capable of cutting synuclein in the same way it’s cut in the human brain. There are only 46 protease genes in yeast. The scientists experimented with them and narrowed the field to one: Capsase-1.
“It got our attention because Capsase-1 is the major inflammatory protease of the human genome,” Petsko said. It triggers the inflammatory cascade in human beings.
What activates Capsase-1? The same things that cause Parkinson’s — viral infections of the brain, mitochondrial poisons, old age.
If you inhibit this enzyme, could Parkinson’s be prevented?
Petsko said a Capsase-1 inhibitor drug has already been manufactured to treat arthritis. Petsko and his colleagues began testing the drug on rats with success.
Petsko and his fellows are beginning the steps to file applications to try this drug on people with Parkinson’s. But Petsko said he expects the drug to fail. Most things you try fail, he said. It’s really hard to cure a disease.
Questions arise such as when to give the drug. Do you give it to someone who doesn’t have Parkinson’s? Will it stop the progress of the disease in someone who already has it?
“You really need to treat the disease before it starts, but we don’t know how to do that,” he said.
He doesn’t know if this is the answer.
“It better get somewhere soon, because the clock is ticking for everyone’s grandchildren.”