Your best bet against dementia is being healthy and exercising. Nothing you can do other than that.
Knowing you have dementia-ridden relatives will only depress you.
So far my tests have been accurate with Nebula. I find the problem. I go into the Dr. They do the official $4 grand genetic check and it turns out it was correct.
The problem with Dr genetic testing is that in my experience they dont check as many variants for the gene. It was explained to me that they check the well established and ones they can do something about.
Whereas Nebula is giving you all the variants they find and you will get many that are of uncertain significance.