Another very inexpensive test to consider is UPSIT -- the University of Pennsylvania Smell Identification Test. It is NOT definitive. But might contribute to a diagnosis. Insurance covered mine for a $5 copay.

Many, but not all PWP's have significantly reduced abilities to smell strong odors.

A search of PubMed will give you the details of how this test is used.

Some studies have concluded that patients with autopsy proven atypical parkinson's ability to smell was not AS IMPAIRED as PWP's.