I had to get a spinal tap done when I was younger. I was hospitalized for a little while and I thought I felt fucked up because of the drugs or the illness. When I got sent home from the hospital I still couldn't move around very well and was stuck in bed. But no, years later I had another bout of whatever it was I had, and this time I didn't get a spinal tap, and was up and about in a couple of days after the illness had past. The most horrendous part is that they lost the results of the test for which the spinal tap was taken.
Of course, given the choice between getting Alzheimer's treated early on and being laid up for a week, I think I'd rather avoid the Alzheimer's. My friend's grandmother had it and my grandfather had it. For me, there's hardly anything worse.