Joy Milne knew something was wrong with her husband long before doctors did. It started with a change in his scent—a musky, waxy odor she couldn’t place. Seventeen years later, when Les was diagnosed with Parkinson’s disease, the pieces fell into place. Then, at a support group, she smelled it again: the same distinct fragrance clinging to others with the condition.

This wasn’t any coincidence.

Now, the 75-year-old former nurse—born with a rare condition called hyperosmia, which heightens her sense of smell—is at the center of a scientific quest to develop the world’s first simple, non-invasive test for Parkinson’s. Working with University of Manchester chemist Perdita Barran, Milne’s olfactory superpower could lead to a swab-based test that looks for signs of Parkinson’s odors in a patient’s sebum, the oily substance secreted by skin.

A Nose That Beat the Neurologists

Joy’s story might have stayed anecdotal, but in 2013 she met Professor Perdita Barran, a chemist at the University of Manchester. Intrigued, Barran devised a simple but telling experiment. She asked Milne to smell T-shirts worn overnight—some by people with Parkinson’s, others by healthy volunteers.

Milne got almost every one right.

Only one shirt from the control group was misidentified. But nine months later, the person who wore it was diagnosed with Parkinson’s. She hadn’t just passed the test. She’d sniffed out the future.

That’s when science began catching up with her nose.

And it’s not just Parkinson’s. The Scottish woman claims that each illness smells different to her.

“I could tell if someone was struggling post-operatively. The big one was walking into a Nightingale ward with 18 beds on it and smelling tuberculosis,” Milne told The Telegraph. “It’s not musky like Parkinson’s. It’s more of an oily biscuit smell.”

What Does Parkinson’s Smell Like?

Parkinson’s disease affects over 10 million people globally. It’s the fastest-growing neurological disorder in the world, second only to Alzheimer’s in prevalence. The disease is thought to be caused by the loss of dopamine-producing neurons in a part of the brain called the substantial nigra, linked to movement and muscle tone. But it’s often diagnosed too late—after more than half of the brain’s dopamine-producing neurons have already died.

Milne can smell it far earlier.

It turns out that the disease alters the body’s sebum—a waxy substance secreted by the skin. In collaboration with Barran, Milne helped pinpoint where the smell lives: not in sweat, but in the oily regions of the forehead, back, and scalp. The compounds behind the odor include molecules like octadecanoic acid, methyl ester, which has a waxy, musty aroma.

Barran’s team collected sebum with a simple swab and analyzed it using gas chromatography mass spectrometry (GC-MS), an analytical technique that identifies the molecules in a sample. The team uncovered a complex biochemical signature: about 27,000 molecular features, 10% of which differ in people with Parkinson’s. There’s no “Parkinson’s molecule” but rather a range of patterns that are associated with the disease, and Milne’s nose is so remarkable it can tease out this subtle bouquet.

No one had realized sebum was diagnostically useful, Barran told The Telegraph journalist Victoria Moore. “We’re measuring the disease and the effect of the disease – and the medication in some cases – on the individual. And no one had ever done that before,” said Barran.

From Super-Smeller to Swab Test

Joy Milne’s nose isn’t the only one getting attention. Her unique abilities have inspired a broader search: for artificial noses, trained dogs, and even an AI platforms that can replicate her sensitivity.

For instance, working with Dr. Claire Guest at Medical Detection Dogs, Barran tested a golden retriever–Labrador cross named Peanut. “The best dog was about as good as Joy,” she said in an interview with The Telegraph.

They hope insights from dogs and Joy’s sense of smell will guide future machine-learning systems capable of recognizing the volatile compounds linked to Parkinson’s. The idea is to digitize the nose, and in doing so, make it medical.

Barran has since founded Sebomix Ltd, a company focused on using sebum as a diagnostic fluid—not just for Parkinson’s, but eventually for other diseases as well. She’s already eyeing potential markers for Parkinson’s-related cardiovascular issues.

The ultimate goal is a skin-swab test that could spot Parkinson’s years before symptoms appear. Early trials, funded by the Michael J. Fox Foundation, show 96.7% accuracy—far better than the 50% accuracy of general practitioner referrals. The test could also help women, who are often diagnosed late because symptoms mimic menopause.

“We plan to determine if those with PD have a distinct sebum profile that is linked with a distinct odor profile that can be detected and identified/discriminated using proposed human/canine/analytical platforms,” said the foundation. The actor Michael J. Fox was just 29 when he announced his Parkinson’s diagnosis in 1991.

But early detection comes with some big and hard questions to face. With no cure yet, is knowing ahead of time a blessing or a burden? For Milne, whose husband passed away in 2015, the answer is that their lives would have been easier had they understood sooner what was about to happen.