St. Michael’s working on test to diagnose Parkinson’s disease

By Leslie Shepherd

St. Michael’s Hospital is part of an international research project trying to determine which emerging medical test would most accurately diagnose Parkinson’s at an early stage. The work is funded in part by the Michael J. Fox Foundation for Parkinson’s Research, named for the Canadian actor who was diagnosed with young-onset Parkinson’s in 1991, and the Physicians’ Services Incorporated Foundation.

Early diagnosis and treatment is critical for patients with Parkinson’s disease, a neurodegenerative brain disorder in which certain groups of brain cells malfunction and then die. Among other things, the brain slowly stops producing a neurotransmitter called dopamine. The less dopamine a person has, the less able he or she is to regulate bodily movements and emotions.

Once the nervous system disorder starts destroying neurons they are gone forever. Yet a patient has only a 50 per cent chance of being correctly diagnosed with Parkinson’s disease on his or her first visit to a neurologist.

Dr. David Munoz, an adjunct scientist in the hospital’s Keenan Research Centre for Biomedical Science, said there are three possible approaches to diagnose Parkinson’s based on the presence of abnormal proteins specific for this condition found in areas outside of the brain.

The first is a biopsy of the submandibular gland, either of a pair of salivary glands found below the lower jaw. But this can be a difficult and invasive procedure, which neither physicians nor patients are keen to endure.

Dr. Munoz’s research project looks at two other options: testing for Parkinson’s during colonoscopies or through a skin biopsy, commonly performed by family physicians testing for skin conditions. By looking at tests conducted at the time of diagnosis, the researchers hope to compile evidence as to which is more accurate.

Dr. Munoz said the benefit of testing for Parkinson’s during a colonoscopy is that the test would just be part of the common test for colorectal cancer. Neurons are also present in the gastrointestinal tract, orchestrating the muscle contractions that move food through the tract.

He said one advantage of a skin or punch biopsy is that it is commonly performed under local anesthetic by family physicians in a doctor’s office or clinic for cancer or skin disorders. A device about the size of a pen nib removes a small piece of flesh.

“Eventually we hope to have a way of changing the diagnosis of Parkinson’s disease, which at this point is subject to a 50-per-cent error rate,” said Dr. Munoz. “Imagine trying to diagnose someone with diabetes without being able to measure their blood sugar.”

About St. Michael’s Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.