I can't speak for fermented papaya, but I measure the effectiveness of my white ratting by using the following program:
This measures the number of times you can type qpqp ... in 30 seconds, using first just the index finger of your left hand then just the index finger of your right hand. It is a computerized version of a test I was given at hospital.
For me the total of the two scores varies from about 25 - 42, as I go from fully off to fully on. A person without Parkinson's will score about 50-60.