Joy Milne noticed a small difference in her husband just before he turned 40. "His smell changed," the Scottish woman tells the BBC. "It wasn't all of a sudden. It was very subtle—a musky smell." He was diagnosed with Parkinson's disease six years later and died in June at age 65. Milne found herself supporting the Parkinson's UK charity, where she noticed others had the same distinct smell. She happened to mention her observation to scientists at a talk, and they later put her to the test, presenting her with T-shirts worn by six people with Parkinson's and six without. "She got the six Parkinson's, but then she was adamant one of the 'control' subjects had Parkinson's," says a scientist. Researchers were impressed and dubbed her a "super-smeller," per AFP. Then eight months later, that one control subject returned to tell scientists he had just been diagnosed with Parkinson's.
Because of Milne's sniffer, scientists now theorize that changes in the sebum—an oily substance produced by the skin—may occur in people with early Parkinson's. Now Parkinson's UK is funding a study that will see swabs taken from 200 people with and without Parkinson's and studied by a team of smell experts, including Milne. The swabs will also be studied chemically. A proven link between an odor and the disease could make for an easy and clear way to identify a disease that is "incredibly difficult ... to diagnose," as the Scotland director of Parkinson's UK puts it. "It would be absolutely incredible and life-changing." Currently, doctors diagnose the disease largely as they have for the last two centuries: by observing a patient and his or her symptoms. (The human nose really is amazing.)