My thanks go to Maxkas on the HealthUnlocked/Parkinson's Movement forum for drawing my attention to this interesting article [1]:

"Why Is It Taking So Long To Find A Cure For Parkinson's Disease?"

Let me add another few reasons:

Little attempt has been made to utilize the abilities of PwP to do the research, rather than just be the subjects of the research.

For some, safer, types of potential therapy, it makes sense to introduce it on a provisional, at cost basis, once it has been tested for safety, but before it has been tested for effectiveness; monitoring the effects as you go along. (I'm thinking of things like Rytary here, not DBS.)

The desire to get a patent distorts the research away from testing naturally occurring substances.

While making sure that a thread based on the article doesn't already exist I came across a pointer to it on NewsBot, 04-22-2016. But, there doesn't appear to be any comment on it.

Reference:

[1] Soania-Mathur, HuffPost Living Canada, 16th April, 2017.
(Originally posted 04/21/2016)
Why Is It Taking So Long To Find A Cure For Parkinson's Disease? | Dr. Soania-Mathur

John