The Woman Who Could Smell Parkinson’s

She first noticed the scent on her husband. Now her abilities are helping unlock new research in early disease detection.

… [Drs Barran] and Kunath ran a small pilot study in Edinburgh. Through Parkinson’s UK, they recruited 12 participants: six local Parkinson’s patients and six healthy controls. Each participant was asked to wear a freshly laundered T-shirt for 24 hours. The worn shirts were then cut in half down the center, and each half was placed in its own sealed plastic bag. Kunath oversaw the testing. Joy smelled the T-shirt halves at random and rated the intensity of their Parkinsonian odor. “She would find a positive one, and would say, ‘There — it’s right there. Can you not smell it?’” Kunath recalled. Neither he nor the graduate student assisting him could smell a thing.
Kunath unblinded the results at the end of the day. “We were on a little bit of a high,” he recalled. Not only had Joy correctly identified each sample belonging to a Parkinson’s patient, but she was also able, by smell, to match each sample half to its partner. Barran’s skepticism evaporated. Still, Joy’s record was not perfect. She had incorrectly identified one of the controls as a Parkinson’s patient. The researchers wondered if the sample had been contaminated, or if Joy’s nose had simply gotten tired. By Barran’s recollection, Kunath’s response was: “It’s fine! It’s one false positive!” Barran herself was slightly more cautious: Joy had mislabeled both halves of the man’s T-shirt.
Of more immediate interest, though, was the question of what was causing the smell in the first place. The odor seemed to be concentrated not in the armpits, as the researchers had anticipated, but at the neckline. It took them several weeks to realize that it perhaps came from sebum, the lipid-rich substance secreted by the skin.
[…]

After nearly a year, however, at a Parkinson’s event in Edinburgh, a familiar-looking man approached Kunath. He had served as one of the healthy controls in the pilot study. “You’re going to have to put me in the other category,” he said, according to Kunath. The man had recently been diagnosed with Parkinson’s. Kunath was stunned. Joy’s “misidentification” had not been an error, but rather an act of clairvoyance. She had diagnosed the man before medicine could do so…

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nytimes.com