Yes, actually one should assume that; not doing so is irrational. There are many other diseases that one might have without even knowing they exist. It would be

Yes, actually one should assume that; not doing so is irrational. There are many other diseases that one might have without even knowing they exist. It would be extremely foolhardy to get tested for them if/when you become aware of them. "given that most of the research is around prevention of damage" Given that aren't any preventative treatments, you're barking up the wrong tree. "surely it's better to get tested early if you even remotely suspect there is a chance of it being Alzheimer's." No, it's surely not.