Scientists know a fair amount about memory loss and brain capability. There is more to it than the proteins. The fact that we talk so much about reversing it without discussing prevention shows where the money is.

Yes, we can mostly prevent Alz/dimentia based on lifestyle. There are whole groups in the world who mostly didn't get it until they adopted certain lifestyle elements.

For example, when cardiovascular disease you often have clogged arteries that reduce the flow of blood. This also reduces the flow of blood to the brain which impedes its performance and ability to clean things up naturally.

Ref: https://www.amazon.com/Alzheimers-Solution-Breakthrough-Symp... [Note, the book language is played up for a general population audience]