当时她已经不认识我的其他的同学和朋友了

Alzheimer disease对于现代医学还是不治之症，最多也只能减缓病情的恶化。2014年有一部电影"Still Alice"就是有关Alzheimer disease的故事，Julianne Moore因此获得当年奥斯卡最佳女演员奖，值得一看。

google了一下：

Why is Alzheimer's disease so devastating?

"As the disease progresses, an individual loses his memory as well as mental and physical function — it is this function loss that leads ultimately to death. Once the disease starts, we are able to slow the progression with currently available medications — but we can't stop it or reverse it."