With funding from Parkinson’s UK and the Michael J. Fox Foundation, Barran’s team has already collected more than 800 samples of sebum, an oily substance secreted by skin, swabbed from the backs of volunteers. In preliminary tests they’ve found several molecules that are elevated in people with Parkinson’s disease. Together, the molecules could create a diagnostic fingerprint for the disease.

— Joy Milne thought her husband smelled different, starting about six years before he was diagnosed with Parkinson’s. Scientists are paying attention; read more at You Can Smell When Someone's Sick—Here's How at National Geographic.