Mum's personality is changing ...worried

[Sonolanona]

Mum is in her late 70s.. intelligent and funny, if a little judgemental. Lives alone (long divorced and my Dad died years ago)
She has become MUCH more anxious over the last couple of years... stresses over everything. Neurotic about her cat, convinced he can't cope if she is away overnight, that he's anxious .. reality is he is simply an old ,demanding cat, no different to most and he manages fine for one night with the neighbour feeding him.
But what is worrying me is she has become quite rude/offensive. She bitches about her few friends, she was horribly rude about my lovely autistic son back in the summer... to the point where DD2 , who was with us out having a meal , was shocked enough to tell my Mum that that was out of order.
She's with us for New year and she upset DD2 by completely ignoring her toddler, while fawning over the other toddler with us, didn't even greet DD2 or her dh, and just isn't herself.
Her memory seems fine and she seems to function fine day to day, but it's like her social filter has gone... and heaven forbid you dare say anything.

Is this the start of dementia? She doesn't seem depressed (often complains she's bored but does a fair few social activities) she's got a few health problems but nothing obviously dreadful, and I'm just worried about her; and miss my Mum as she was :(

Just to add..... i understand that with alzheimers there is medication which can help

Would be helpful if she'd sign a letter which allowed you to talk to her GP surgery. It's one of the most useful things we've done for everyone's sake.

I'm going through this with my gran. She's completely alert and oriented and remembers all the day to day stuff but just generally much more selfish and rude at times about things when she was always such a delight. People who she hasn't seen for a few years she often completely forgets as if they never existed. Even if she bought them a Christmas present every year.

My grandad'a first sign was very subtle. We were playing a game at Christmas and he had to draw a giraffe. He drew a crocodile and the kids were saying crocodile and he 100% thought he had drawn a giraffe. It was so bizarre and all the adults in the room were were looking at each other worrying and the kids were just annoyed they missed a point.

The older generations can be more prickly, rude, DS said dad's got no filter these days. But I've noticed it in his old cronies too. He's very good with technology but doesn't suffer fools even though he can be one too. He's more intolerant too. But I wouldn't say it dementia. He has aches and pains which don't help. He really doesn't like getting old.

Is she dehydrated OP? Things like kidney infections and other UTIs can cause all sorts of issues in the elderly, including increased agitation

When my Dad started to show signs of cognitive changes, I rang his GP surgery and had a good chat to the receptionist. She added my concerns to Dad's notes, and when he was next in, they did some checks.

Dad's changes sadly turned out to be cancer related - so it isn't always dementia, and as a PP mentioned, really simple things like dehydration or a UTI can make someone agitated/not themselves. I'm sorry to say that you need to start getting investigations done - I would start the ball rolling with her GP surgery.