I can remember forgetting what I was going to bring up in conversation back in my twenties though. I blame this all on my not very linear mind. You could call me scattered or you could call my mind playful. Let's say it flits about hither and yon making connections as a regular conversation is going on. Once in a while I'll start to bring up the connection, and then blank on it... usually the connector pops back up a little bit later. I suppose this phenomenon is worse now, but it was not entirely new in my menopause years.
On words - since I'm not working in landscape design anymore and am in a new state where my local planting vocabulary is on the spare side, my much larger old planting vocabulary is getting rusty. Even some general cultural names are dropping like flies. For example, the other day I was trying to remember the guy who opened the aqueduct to LA with the words "There it is. Take it." Started with M. First I thought of Mallinkrodt, an old chemical company. Then Marshall. Then what, I dunno, but several other M words. I refilled my coffee cup and came up with it. Mulholland. Brrrr, I call this word outflow.
Which reminds me, anyone read the fascinating description of what it is like for a writer/poet to lose his word access because of a glioblastoma brain tumor? I read this within the past week or so. Too bad I didn't keep a link, as I don't remember where I read it. I guessed the Guardian, but can't find it there.
Aha, it's in the Observer - I take it the Sunday edition of the Guardian.
http://www.guardian.co.uk/books/2010/nov/07/tom-lubbock-brain-tumour-language