Experts meet to tighten grip on disease

January 16, 2008
http://ottawasun.com/News/OttawaAndR...75253-sun.html
By ANN MARIE MCQUEEN, SUN MEDIA


Shelby Hayter didn't skip a beat when she got her Parkinson's disease diagnosis three years ago.

Within 48 hours, she was making calls about fundraising. A month later, she was running the Boston Marathon for which she'd already qualified.

She had also managed to raise $36,000 for Parkinson's research from friends, neighbours, hockey teams, church groups and family members.

"I just thought, 'Well, what am I going to do about this?" said the 43-year-old mother of three. "And just refocused really quickly."

Hayter was later asked to join the board of the Parkinson's Research Consortium, a group of 17 scientists affiliated with the Ottawa Hospital, the Ottawa Health Research Institute, the University of Ottawa and the National Research Council.

On Friday and Saturday, the consortium will host a meeting of about 40 top Parkinson's scientists and clinicians.

EXPAND SCOPE

It's the first time such a key group of people will gather, said Dr. David Grimes, co-chairman of the Parkinson's Research Consortium.

"The scientists can get very focused on one very narrow area, and the idea is if we can expand the thinking process a little bit ... we can hopefully get things done faster," he said.

Parkinson's is a neurological disease that causes slowness of movement, tremors, balance problems and stiffness.

Recent research has cast doubt on the prevailing belief that a lack of dopamine is the sole cause. Scientists now know Parkinson's can be triggered when other cells throughout the brain die, too.

"It's a very complicated process and in any one person the progress isn't going to be the same," said Grimes. "But there are common pathways where these cells are dying where we can interfere."

Hayter didn't stop her fundraising and awareness efforts after the marathon. Last year she took a doctor and a researcher into nine local schools to give a two-day, participatory seminar. This year, it's up to 14 schools. She's also raised another $14,000.

Despite seeing her disease progress -- Hayter has tremors in her left side now, a limp in her gait and a slight slide in her left foot -- she felt compelled to keep speaking up.

"For me the biggest hurdle is that Parkinson's affects the older generation, so there's such a weak voice ... young onset you have to focus on your family, your job, maintaining your health," she said. "That leaves not that many people who have the time and the energy, who are willing to be public about it."

Thanks Carolyn. What struck me in this report is the following statement:
"Recent research has cast doubt on the prevailing belief that a lack of dopamine is the sole cause. Scientists now know Parkinson's can be triggered when other cells throughout the brain die, too"
I think perhapse the time will come when treatment of PD abandons the one track aproach (that is Dopamine replacement)

Scientists Find Link Between Dopamine and Obesity

UPTON, NY -- Dopamine, a brain chemical associated with addiction to cocaine, alcohol, and other drugs, may also play an important role in obesity. According to a study by scientists at the U.S. Department of Energy's Brookhaven National Laboratory, obese people have fewer receptors for dopamine, a neurotransmitter that helps produce feelings of satisfaction and pleasure. The findings, which will appear in the February 3, 2001 issue of The Lancet, imply that obese people may eat more to try to stimulate the dopamine "pleasure" circuits in their brains, just as addicts do by taking drugs.

"The results from this study suggest that strategies aimed at improving dopamine function might be beneficial in the treatment of obese individuals," says physician Gene-Jack Wang, the lead scientist on the study.

Brookhaven scientists have done extensive research showing that dopamine plays an important role in drug addiction. Among other things, theyıve found that addictive drugs increase the level of dopamine in the brain, and that addicts have fewer dopamine receptors than normal subjects.

"Since eating, like the use of addictive drugs, is a highly reinforcing behavior, inducing feelings of gratification and pleasure, we suspected that obese people might have abnormalities in brain dopamine activity as well," says psychiatrist Nora Volkow, who was also involved in the study.


The lower PET scan images, labeled FDG, show glucose metabolism in the brains of obese and control (comparison) subjects. There are no differences. The upper PET scans show where the radiotracer C-11 raclopride binds to dopamine receptors. These images show that obese subjects have fewer dopamine receptors than control subjects.

To test this hypothesis, the scientists measured the number of dopamine receptors in the brains of ten severely obese individuals and ten normal controls. Their method consisted of giving each volunteer subject an injection containing a radiotracer, a radioactive chemical "tag" designed to bind to dopamine receptors in the brain. Then, the researchers scanned the subjects' brains using a positron emission tomography (PET ) camera. The PET camera picks up the radioactive signal of the tracer and shows where it is bound to dopamine receptors in the brain. The strength of the signal indicates the number of receptors.

Obese individuals, the scientists found, had fewer dopamine receptors than normal-weight subjects. And within the obese group, the number of dopamine receptors decreased as the subjects' body mass index, an indicator of obesity, increased. That is, the more obese the individual, the lower the number of receptors.


"It's possible that obese people have fewer dopamine receptors because their brains are trying to compensate for having chronically high dopamine levels, which are triggered by chronic overeating," says Wang. "However, it's also possible that these people have low numbers of dopamine receptors to begin with, making them more vulnerable to addictive behaviors including compulsive food intake."

The researchers note that, based on this study alone, they cannot conclude whether the brain changes they've detected are a consequence or a cause of obesity. They also acknowledge that the regulation of body weight is extremely complex, involving many physiological mechanisms and neurotransmitters. But they do suggest that addressing the dopamine receptor deficiency or finding other ways to regulate dopamine in obese people might help reduce their tendency to overeat.

Unfortunately, many of the drugs that have been shown to alter dopamine levels are highly addictive. But exercise, which has other obvious benefits in weight control, is another way obese subjects might be able to stimulate their dopamine pleasure and satisfaction circuits, the researchers suggest. "In animal studies conducted elsewhere, exercise has been found to increase dopamine release and to raise the number of dopamine receptors," Volkow says. This suggests that obese people might be able to boost their dopamine response through exercise instead of eating - just one more reason to exercise if you're trying to lose weight.

This study was funded by the U.S. Department of Energy and the National Institute on Drug Abuse, part of the National Institutes of Health.


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The U.S. Department of Energy's Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies. Brookhaven also builds and operates major facilities available to university, industrial, and government scientists. The Laboratory is managed by Brookhaven Science Associates, a limited liability company founded by Stony Brook University and Battelle, a nonprofit applied science and technology organization.