New Research Discovers What Parkinson's Disease Smells Like

There currently is no single “test” to diagnose Parkinson’s disease. Instead, doctors must evaluate symptoms like shaking, tremor, stiffness and balance issues, common symptoms of other conditions when diagnosing the disease. In its early stages, a correct diagnosis is particularly difficult. But a new study explores the possibility that Parkinson’s disease may be diagnosable before visible symptoms appear due to its signature smell.

What is Parkinson’s Disease?

A new study published earlier this month in the journal ACS Central Science looked at the sebum of 43 people with Parkinson’s disease and 21 people without. Sebum is a waxy substance secreted by the skin that people with Parkinson’s tend to secrete more of. The sebum was evaluated using gas chromatography-mass spectrometry. Researchers found three compounds that appeared at higher-than-average levels among people with Parkinson’s disease: eicosane, hippuric acid and octadecanal. They also found a fourth compound, perillic aldehyde, that appeared at lower-than-average levels.

These compounds are notable because they are all associated with a distinctive “Parkinson’s smell,” described as a “woody, musky odor” by a woman named Joy Milne. She first became known to researchers at a lecture about Parkinson’s disease in 2012, during which she stood up and asked Tito Kunath, a researcher at the University of Edinburgh, why they weren’t “doing something about the fact that people with Parkinson’s smell.”

Intrigued, Kunath and Perdita Barran, professor of mass spectrometry at the University of Manchester (who became the lead author on the study) tracked Milne down and discovered that she is a “super smeller,” or someone who has a highly developed sense of smell. Her now-late husband had Parkinson’s disease, and she had noticed the odor on him 12 years before he was diagnosed. At a patient support group, she discovered everyone there had the same smell.

Kunath tested her sense of smell by giving her 12 shirts worn by people with and without Parkinson’s disease. She correctly identified all six shirts worn by people with Parkinson’s, and also identified one shirt that belonged to someone who was diagnosed with Parkinson’s eight months later.

For Barran’s study, Milne helped confirm which chemicals made up the Parkinson’s smell. The Guardian reported that Milne can also smell other conditions: Alzheimer’s smells like vanilla, and cancer smells earthy.

After the results of the latest study, researchers are working on developing a diagnostic test and training dogs to learn the scent. An earlier Parkinson’s diagnosis means the potential for earlier treatment and more time to develop the right support and lifestyle strategies.

If you’re newly diagnosed with Parkinson’s disease or suspect you might have it, there is support out there for you. Check out these articles for guidance from others who are living with Parkinson’s disease: