Researchers found that Parkinson’s disease might be diagnosed years before the first symptom appears by performing a smell exam called the Brief Smell Identification Test (BSIT), which has people identifying strong odors, such as lemon and gasoline.

According to the study published in the journal Neurology, adults who have a poor sense of smell and can’t perform the test adequately, present a higher risk of developing the chronic and progressive movement disorder than other adults whose sense of smell works fine.

Image Credit: Herald & Review / Jim Bowling
Image Credit: Herald & Review / Jim Bowling

According to the study’s author and professor of epidemiology and biostatistics at the Michigan State University College of Human Medicine, Dr. Honglei Chen, “a poor sense of smell may predict the risk of Parkinson’s disease up to a decade, and this is particularly true for white men… Research on olfactory impairment may eventually help us identify high risk populations and understand how Parkinson’s disease develops in the first place,” he told Healthline.

Doctors found an association between sense of smell and Parkinson

In the BSIT, doctors gave patients different samples with 12 distinct odors – including lemon, gasoline, onion, and cinnamon. The test was easy: they only had to answer which smell belonged to each object.

Researchers studied for 10 years 1,510 Caucasians and 952 African-Americans, whose ages were mostly around 75. The test showed that those whose senses of smell were poor, were five times more likely to develop Parkinson’s.

From an isolated group of 42, the results revealed that 30 Caucasian and 12 African-American developed Parkinson’s. After they were finished, the doctors separated the study subjects into three new groups based on their scores: poor, medium, and good sense of smell.

There were 26 cases in the first group, those with the poor sense of smell. Likewise, nine individuals were included in the medium group and seven in the group with the best sense of smell.

“Evidence suggests olfactory [sense of smell] impairment may develop years prior to the diagnosis of Parkinson’s disease and dementia, the so-called neurodegenerative diseases that we are yet to find a cure for,” Dr. Honglei Chen. “While the sample sizes in specific groups are small in this study, especially in blacks and women, the association appears to be stronger in whites than in blacks, and in men than in women.”

Currently, there are around one million people living with Parkinson’s disease in the United States – including the 60,000 Americans that are diagnosed each year. Worldwide, there is data of at least 10 million people living with this disease that affects people’s neurons, according to Parkinson’s Disease Foundation.

Parkinson’s kills substantia nigra. This affects the production of dopamine, a chemical that sends messages to the brain and lets people move and maintain coordination.

This neurological disease gets worse over time, and there is not any cure for it. However, there are many medications and surgeries to treat people who have Parkinson’s.

Source: Healthline