Yeah, more data is always nice. I do think the next few decades will be interesting as we've already seen increased incidents in countries that previously didn't have many, and more countries seem to be adopting a western lifestyle.
I don't think any single factor will ever be discovered to be the cause, I just think that a slew of factors increase the chance the brain reaches the tipping point where things start to go wonky and the brain is creating more tangles, failing to successfully create new neurons, and isn't properly flushing out the tangles during sleep.
Like, for example, statins, they say they aren't sure if they help or not, but on the one hand you have people who are perhaps suffering more from the vascular aspects and it might help them a bit more than others, but on the other hand it might make things worse for some if there is some interaction where it's interfering with myelin health.
Well that's sort of the deal with medicine, everything has a trade off. Incorporate drugs to modify aspects of your bodies function when the net effect will extend your life. Their ain't no such thing as a free lunch. I take hypertension medication, knowing full well that it's damaging my circulation. I must work to mitigate that damage, but irregardless, I would die much sooner from my blood pressure damaging my arteries and organs the opposite way, then I will from the BP meds.
Same goes for everything, statins are no excepton. They don't come with out a cost, but for some, that cost is less then not using.
I wish people thought more about what medications are, and didn't just think they were cost free.