According to the BBC a women can smell Parkinson's.
Based purely on smelling an article of clothing, with 6 PwP and 6 controls she was right 11 out of 12 times. Her one mistake was to identify one of the controls as having PD - but 8 months later he was diagnosed with the disease.
http://www.bbc.co.uk/news/uk-scotland-34583642
John