Thank you very much for that question.
I think you're absolutely right, and it's really been a shift in the way we think about Parkinson's disease. Literally 15 years ago people were completely focused on the motor components—the tremor, the slowness in movement. As we've gotten better at treating those parts of the disease, it's become very clear that patients have many other features. Maybe more interestingly, and I think this is what you're getting at, some of these features appear years if not decades before the motor manifestation.
I think this is really an opportunity to identify these people. I won't call them “patients”, because they're not really patients yet, necessarily. There are certain features...for example, a loss of smell. Almost all patients with Parkinson's lose smell. This is something that you could easily identify, possibly on a population level, as you were hinting at. Other things include sleep abnormalities, which occur sometimes a decade before.
One study led by a Canadian group—Ron Postuma at McGill—showed that there's a certain kind of sleep disorder, called REM sleep behaviour disorder, a very distinctive sleep disorder, and about half of the people who have that disorder, which is a huge amount, go on in the next decade to develop Parkinson's or Parkinson's-like disorders. You can imagine that if we had a way of identifying this subset in the population, it would be tremendous. You could not only potentially help them symptomatically, but if there were new breakthroughs in neuro-protective therapies, these would be the ideal patients to try to target.
I don't know if we this mentioned earlier, but by the time someone presents in your office with Parkinson's disease, about 70% of their dopamine neurons are gone. It's very late in the game by the time you see the patients. So if you could identify these people 10 or 15 years earlier, that would be tremendous.
I think Canada is ideally positioned to do those kinds of studies you're hinting at, because there's a very good cooperative, collegial atmosphere among the different research centres, among the different Parkinson's clinics. I think we're really poised to do those kinds of studies.