It's good that your mother had the support structure of other folks to notice the changes, not everyone is so lucky.

You'll eventually know either way, at least you get to plan ahead more with an earlier diagnosis minimizing the potential for hurting yourself or others. That's not the main point though, this can be used to check if treatments are working at slowing the disease or not.

I feel that enough anecdotal experiences should have been relevant to previously determine this. Not that it's good to use that but it seems like everyone already knew this.