My grandfather had it, my wife’s grandmother had it, and it begins like this....................
My mother feared Alzheimers above all.
When I would go to visit, she would make recitations. She would recite the left handed cousins. ( I am left handed and to her dying day she would apologize for me being left handed). There was a family we knew with 10 kids. She would recite them in order. She would casually introduce the subject of marriage and then recite which of my highschool classmates ( of 40 years ago) married which. An on and on, birth days, anniversaries etc.
Her mind remained pretty sharp till the end
My mom has it and it is really sad. Most of the times she has no idea who I am.