@Roberta,
I have a pretty swifty short term memory, but am lagging on occasional words I used to know. Haven't worked re specifying plants in seven years and am starting to forget some of the latin names, although I can picture the plant and its location if I'd seen it and not just read about it. I'll have an idea that it starts with, say, C, and will be apt to remember the word in something like five minutes. It sort of pops to the top through the brain jelly, having been there but buried. Similarly, I've spaced out on the names of some of my husband's friends/acquaintances, or, egads, some of mine from long ago, and similarly, they pop up on the front page after a while. I know this isn't alzheimer's but it can be aggravating. Yet I think I've always had this process going on in some way.