Thanks for this Olsen.

It's a pity that this paper is behind a paywall, because the question being asked is very important, and the causality issue is particularly difficult to assign here.

How does this paper deal with the possible cases of doctors putting those patients who are progressing most rapidly or who appear to have been diagnosed later on levodopa sooner?

Interestingly, perhaps, my own experience has if anything been in support of the paper: diagnosed 12 years, I initially went drug free, then rasagiline was prescribed, then ropinirole was added, before levodopa was added after 4 years, and I still have no sign of dyskinesia.

To take it further I've only seen one case of dyskinesia in my support group of about 20 PwP. However, let me point out that there are many confounding issues, not least, the self-selection of people who attend support groups.

John