Dulled sense of smell might predict Parkinson's

Margie Chamberlain's last birthday was more than a milestone. It was a painful reminder.

"I'm 51 and when my mother was diagnosed with Parkinson's, she was 50 or 51. Nobody should have to go through what my mother went through," said Margie Chamberlain, whose mother died of Parkinson's.

This could be a step in that direction. Researchers want to know if this smell test can identify healthy people who are at risk of developing Parkinson's.

People with a normal sense of smell can identify around 35 of these 40 smells correctly. People with Parkinson's -- 20 or less.

"The difficulty with identifying odors or smells is a very early manifestation. It actually may occur years before they develop Parkinson's disease," said neurologist Dr. Kapil D. Sethi.

Dr. Kapil D. Sethi says by the time patients start showing symptoms like tremors, they've already lost more than half the brain cells that are key to motor control.

"I hope and pray I don't have Parkinson's disease," said Chamberlain.

By studying brain scans, smell tests and other early indicators, researchers want to develop medications to stop Parkinson's before it starts.

"We could intervene before they get Parkinson's, so maybe delay it by three or four years. Wouldn't that be wonderful? It would have a huge public health impact," said Dr. Sethi.

For Margie, joining the Parkinson's study is a way to honor her mom.

"I love her. I hope she knows I am doing this for her," said Chamberlain.

The University of Pennsylvania is leading the Parkinson's study, which is recruiting 15,000 people at 17 sites around the U.S. participants must be over 50 and have a mother, father, child or sibling with Parkinson's.

Web Extra Information:

BACKGROUND: According to the National Parkinson Foundation, Parkinson's disease affects one in 100 people over age 60. The neurodegenerative disease is nearly impossible to predict, impossible to prevent and impossible to cure. Symptoms like limb tremors, slowness of movement, rigidity of the limbs or trunk and poor balance are warning signs of the disease. Although symptoms are initially mild, the disease and symptoms progress over time. The speed of progression varies by patient. The only treatment options available for Parkinson's are those that manage its symptoms.

DETECTION: There is currently no laboratory test to confirm the presence of Parkinson's, the Parkinson's Disease Foundation says. Doctors rely on physical neurologic examinations and measures like the Unified Parkinson's Disease Rating Scale (UPDRS) to confirm that a patient has the disease. The UPDRS consists of four parts, the first two based on information provided by the patient about performance at home in a variety of daily activities like dressing, walking and eating. The other two parts consist of a careful examination by the neurologist involving asking questions like: Is the facial expression blunted? Is there stiffness in the limbs or neck? Can the patient get up out of a chair easily? Some tests can rule out Parkinson's by picking up other causes of the troubling symptoms. Blood tests can pick up abnormal thyroid hormone levels and liver damage, and imaging tests can check for tumors or stroke. In addition, PET scans and Beta-CIT-SPECT scans can detect low levels of dopamine in the brain -- a key symptom of Parkinson's; however, these scans are not commonly performed because of their high cost and experimental nature. An emerging method of screening for Parkinson's is smell testing.

IT'S IN THE NOSE: The University of Pennsylvania Smell Identification Test (UPSIT) is the most widely used olfactory test in the world. Investigations at the University of Pennsylvania Smell and Taste Center using the test have shown that, despite anecdotal evidence suggesting it, blindness itself doesn't enhance a person's sense of smell. The test has also revealed head trauma is one of the most common causes of smell dysfunction behind upper respiratory, nasal and sinus infections. The test is also administered on patients with neurological disorders like Alzheimer's and Parkinson's disease. Numerous studies have linked Parkinson's to olfactory dysfunction, or a damaged sense of smell. A 1997 United Kingdom study on cadavers of Parkinson's patients found olfactory damage to be consistent and severe, according to the Journal of Neurology, Neurosurgery, and Psychiatry. Another study in 2005 looked at 24 patients with early-stage Parkinson's patients using UPSIT. They found sense of smell to be highly correlated with abnormalities in the dopamine transporter. These abnormalities are a key symptom of the disease.

Researchers at the University of Pennsylvania are now investigating a new use of UPSIT. Rather than administering it to assess damage caused by Parkinson's, they are testing its usefulness as a predictive measure. Researchers plan to recruit 15,000 close relatives of Parkinson's patients across the country and administer UPSIT. Based on the test results, participants will be divided into two groups: those with a normal sense of smell and those without. Both groups will undergo neuroimaging analysis to identify changes related to Parkinson's.


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