Targeting the saints, not the sinners?
Is it true only the good die young? Research shows risk-takers and wild ones seem less afflicted with Parkinson's disease.
By SUSAN ASCHOFF
Published March 23, 2006
We want to believe we can outwit disease.
We eat whole grains and teetotal and run for our lives in one place on treadmills.
Yet recent research suggests straight arrows - the personality types who don't drink or smoke, who drive the speed limit and arrive on time for appointments - may be more at risk for Parkinson's.
Doctors and researchers have known for years about the link between the nerve disease and certain personality traits. In several recent studies, they've attempted to test why daredevils and sinners, if you will, are less at risk than prudents and saints.
Dr. Robert Hauser, a neurology professor at the University of South Florida College of Medicine, says Parkinson's patients tend to be straight shooters and high achievers: the late Pope John Paul II, former attorney general Janet Reno, boy-next-door actor Michael J. Fox.
"There's been this idea a long time that there might be this Parkinson's disease personality," says Hauser, director of the Parkinson's Disease and Movement Disorder Center at USF. "People who get Parkinson's disease are not the wild ones. No one knows why at this point."
The disease occurs due to impairment or death of nerve cells in the brain that coordinate physical movement. The cells' deterioration reduces production of dopamine, a chemical necessary for these cells to communicate. Symptoms include tremors or shaking, slowness of movement, stiffness and difficulty with balance. Smaller muscle changes may be evidenced in a stiff facial expression, mumbling and small, cramped handwriting.
For years anecdotal evidence has suggested that Parkinson's patients are much less likely to smoke or drink alcohol or coffee than the general population. In the February issue of Neurology, Neurosurgery and Psychiatry, researchers in London reported on a study that looked at the use of tobacco, alcohol and caffeine in 106 Parkinson's patients and 106 people without the disease.
Those with Parkinson's overwhelmingly abstained. They also scored as more anxious and less willing to take risks than those without the disease on psychological tests.
"Smoking has come up as an inverse risk factor in many studies. We don't want to go out and promote smoking, but there's some relationship," Hauser says. "Is it a genetic component that people who are risk-takers are more likely to smoke? Do (Parkinson's patients) not smoke because they have a Parkinson's personality?"
A key question is whether someone with Parkinson's finds little appeal in these vices emotionally or physically, or if those who indulge get something out of cigarettes and coffee that actually wards off the disease.
Could fate finally be cutting sinners some slack?
Not so fast.
"It is a chicken-and-egg question," says Paul Sanberg, a neuroscientist and director of the USF Center of Excellence for Aging and Brain Repair.
Personality traits are increasingly part of medicine's search for the causes and cures of diseases. Scientists are looking at people who are stressed to determine why some get sick and others do not. A year ago the journal Cancer published a study of almost 30,000 twins sparked by the idea that people who are worriers are more likely to get cancer. No association was found between neurotic behavior and cancer. Nor was there a link uncovered between cancer incidence and extroverts. Some have theorized that extroverts increase their risks for cancer because they indulge in more risky behaviors.
Parkinson's patients do have less dopamine in their brains, so they "tend to be more monochromatic. Their personalities may tend to narrow," Sanberg says.
Dopamine also governs the brain's reward mechanisms. On some of the brain's receptors, increased dopamine creates a feeling of euphoria or pleasure. Cocaine users, for example, may get a spike in dopamine, as do some gamblers and drinkers.
Feeding the Parkinson's personality theory are some bizarre side effects experienced by a small number of patients given frequently prescribed dopamine medications.
In a Mayo Clinic study published last summer, some subjects temporarily developed compulsive behaviors, which may include excessive gambling, overeating, increased alcohol consumption and an obsession with sex. The behaviors stopped when the drug was discontinued.
The consumer publication Health Day reported one of the patients, a 52-year-old man, started gambling after his dose was raised. His wife said he lost more than $100,000, gained 50 pounds and developed an obsession with sex that resulted in an extramarital affair. Another man with no history of gambling began spending days in casinos and having sex four times a day.
Fewer than 5 percent of Parkinson's patients receiving the drugs, in these cases pramipexole or ropinirole, will develop compulsive behaviors.
"You try to understand all the information," says Sanberg. Are obsessive-compulsive gamblers, for example, trying to keep their dopamine system firing? he says.
Why not adjust natural dopamine levels in individuals who suffer from addictions or, adversely, from risk-averse conditions such as agoraphobia?
It's not that simple, Sanberg says. There is no single formula for delivering the correct amount of the chemical to the correct brain receptors. Receptors can slow or shut down. The brain compensates. "It's like after you've smoked a while, the cigarette doesn't give you quite the same kick," Sanberg says
At USF, researchers are looking at epilepsy medications to treat Parkinson's. Hauser says retinal cells - cells found in the back of the eyeball - are being harvested from cadavers. These cells can produce levodopa, a form of dopamine; they are being cultured on gelatin spheres for implantation in the brain.
No one is suggesting that the population should turn to partying to avoid Parkinson's.
"I think people should be good," says Hauser, "and be rewarded for that" with good health. He says he is a Parkinson's personality type, following a clean lifestyle. There are no guarantees.
Though less than 1 percent of the population will get Parkinson's disease, research about its origins may explain if it is our bodies programming us to be sinners or saints, ill or well.
Susan Aschoff can be reached at firstname.lastname@example.org or (727) 892-2293.