Barmaid, Thinking of you. Is he coping OK at work?
It may be worthwhile just having a word with one of his colleagues. Someone you trust very well not to discuss it with anybody else.
Personally, I think his drugs/depression/pressure of work are the most likely cause of this. In Mr LL's case it happened after a major heart attack, as I said, as this is quite a common thing. Mr LL copes at work very well still and remembers important dates etc., but just doesn't remember day to day things or conversations we have. He lacks concentration completely when it comes to mundane things.
I wouldn't personally worry too much about Dementia - especially if he is coping at work with such a major issue. It sounds to me very much as if this is taking priority over everything else in his mind and he just isn't coping very well with more mundane issues.
Dementia affects other things apart from memory, e.g. agitation, change in personality.
Take care of yourself, won't you. xxxxxxxx