My brother's wife has got the beginnings of dementia (she hasn't yet been properly diagnosed, so we're not sure of the type). It's really sad. She's a lovely, quiet, gentle woman - or was - who used to be a carer (so did I, and my brother, too, we all worked for the same company). My brother is finding it all a bit much - suddenly having to do everything in the home as well as cope with his wife's aggression, accusations, etc.
My other sister-in-law (husband's sister) rang my husband the yesterday, wanting a favour (the only time she ever gets in touch - we haven't seen her for 3 years - and so I spoke to her as well. I happened to mention my brother's lovely wife (they'd met a couple of times, many years ago) and how her short-term memory has gone, to the point that she (lovely SIL) couldn't remember what she'd had for dinner, 2 hours previously. Husband's sister laughed at that! When I said it's not funny at all, she accused me of being too serious, said I should have a laugh about it. Stupid, insensitive cow. No empathy at all.
Sorry for the long ramble, I needed to get it off my chest.