Joy Milne has always had a keen sense of smell, so she was unfazed when her husband, Les, began emitting a subtle musky odor. He was an anesthesiologist who worked long hours, and Milne assumed the smell was just sweat. But with the change in scent came a growing tiredness that was explained by a devastating diagnosis six years later: Les had Parkinson’s disease.“I could always smell things other people couldn’t smell,” Milne said during a BBC broadcast Thursday. After attending a meeting for the charity Parkinson’s UK, where the other Parkinson’s patients shared her husband’s musky scent, she realized that the...