• There is no test which will return a diagnosis of PD, therefore......
  
• ...... diagnosis is based on the clinical judgment of the doctor.
  
• It is usual for at least two of the three major symptoms to be present before a diagnosis of PD is made.

The PD experience

The simple fact of the matter is that a diagnosis of Parkinson's Disease is the opinion of the doctor. This makes it very easy for the newly diagnosed PWP to convince themselves that the diagnosis is a mistake. Sadly this is seldom the case. Neurologists rarely mis-diagnose PD. If doubt persists it should be dispelled by a positive response to medication.
A bit of a mixed blessing that. The improvement you do want, confirming the PD you don't want.

Parkinson's is just like the rest of life --- full of trade-offs.