Why I was comparing alcoholism to dementia
Back when my boyfriend was still drinking and in denial, he would frequently ask me, "what's it to you how much I drink?" and "how do my drinking habits affect you?" and so I gave the most accurate (to me anyway) description I could: "when you're drunk, you act just like your grandmothers do" (both of his grandmothers have forms of dementia and repeat the same things over and over again, one of them says things that don't make sense, and they exhibit other behaviors similar to a drunk person). So that's where the comparison comes from.