I just caught the last half of this episode. The conclusion: post-mortem brain tissue analysis of "super seniors" (100+) in the study who still had excellent cognition to the end showed the presence of amyloid plaques and tau cell tangles and TDB-43 cells they *thought* were linked to dementia and ALZ. After this study they literally know less than when they started. The scientists leading this study feel that dementia and ALZ are from a gene or a combination of genes.
So solving the AD disease has a long way to go. Misdiagnosis is not unusual. The singer/actor Kris Kristoferson ( A Star is Born) was originally diagnosed with AD because of his memory issues. The drs thought this was brought about by repeated concussions he received many yrs ago. After living for yrs with this tragic diagnosis, a doctor screened Kris for lime disease. It came back positive. Lime disease is treatable and totally recoverable. AD is terminal.