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Loss of Smell and Parkinson’s Disease

Thursday February 25, 2010

Robert Rodgers, Ph.D.

About Parkinson's Disease - QUESTION:

A pre-diagnosed Parkinson symptom was the loss of my sense of smell. It rarely appears on medical information forms, and if brought up during examination noted but never gone further in discussion.

I wonder about this. If it was a matter of lose of touch, hearing or sight, would this be treated differently? Why is it downplayed? Are there any known recovery methods, studies or treatments concerning this condition?

Response:

Researchers have known for at least 30 years that persons with the symptoms of Parkinson’s have an impaired sense of smell. Several studies were released in 2008 confirming the link. The impairment in ability to smell involves more than being able to take in the full essence of a scent. Individuals with the symptoms of Parkinson’s have greater difficulty distinguishing one order from another, or are unable to detect any order whatsoever.

There is currently considerable research interest in the link between Parkinson’s symptoms and the loss of smell now that it has become clear that the two are inextricably linked. Loss of specific smells in particular have also been linked to Parkinson’s symptoms, which is interesting in itself.

Some researchers are currently working on designing a diagnostic smell test for Parkinson’s. There is no definitive test at present that gives a clear indication of Parkinson’s. A smell test will also not be definitive, but it can be used in conjunction with other evidence. I suspect such tests will soon be routinely offered to patients.

The Pennsylvania Smell Identification Test is often used by many neurological clinics to evaluate neurological imbalances. This test evaluates a person’s ability to detect 40 scents. People who take the test can are able to identify on average 35 of the 40 odors correctly. Parkinson’s patients can identify 20 of the 40 odors or less.

Researchers predict that people with seriously impaired olfactory functions have five times the risk of developing Parkinson’s than those with the highest olfactory function.

In light of your interest in this question, I will set my intention to interview some of the researchers who are currently conducting studies to evaluate the connection between the ability to smell and the symptoms of Parkinson’s. To be sure, it is an interesting line of inquiry which may lead to understanding the underlying factors that are at play.