Joy Milne, 65, told researchers that she had noticed a change in the odour of her late husband, Les, years before he developed symptoms of Parkinson's.
He passed away from the disease, a nervous system disorder whose symptoms include shaking and slowness of movement, earlier this year at the age of 65.
"I've always had a keen sense of smell and I detected very early on that there was a very subtle change in how Les smelled," Milne, from Perth, Scotland, said on today.
About one in 500 people suffers from Parkinson's, a degenerative illness that is difficult to diagnose and for which there is no cure.
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Milne made the connection between the smell and the disease after picking up the same scent from other sufferers.
She went on to tell researchers, who dubbed her "super-smeller" after finding that she could identify Parkinson's sufferers from T-shirts they had slept in.
That prompted research charity Parkinson's UK to this week launch a project to find whether the disease and odour are linked.
"Not just on early diagnosis, but it would also make it a lot easier to identify people to test drugs that may have the potential to slow, or even stop Parkinson's, something no current drug can achieve."
Researchers are investigating whether the condition triggers changes in sebum, an oily substance secreted by skin, and aim to recruit 200 people with and without the condition for the study.