There can be many signs but speaking from my own experience with my mother and grandmother, the argumentativeness can stem from embarrassment at having miss judged something or forgotten something - a cover in other words. People can lose social boundaries too and become obsessive and secretive. My mother used to create imagined visitors and conversations and she’d constantly get lost or lose things. Paranoia is another sign.

It's hard to judge what is dementia and what is odd behaviour engendered by isolation and loneliness. I recognise some of this behaviour from my own mother. Attention seeking in groups, ill judging social situations, dogmatic opinions, rudeness. Talking at you rather than to you, not remembering what she has said before or what you have said to her. Sudden bursts of aggressive attitude. I don't have Power of Attorney so have no idea how to approach things. I am left doing the caring , no other member of the family is interested. It's a real worry.
My mother can be all sweetness and light and then suddenly become suspicious and nasty. I sympathise with you.

Another thing, obsessing about childhood as though her whole adult life never happened. Is that normal or not? No idea. I don't know much about dementia.

I'm also noticing signs in elderly parent, but I'm not sure if he's lacking insight or it's as I've got older I can see through him more

All of this can be down to the aging process, whilst they are potential signs of dementia just concentrate on enjoying the years you have with your mum because even if you went to the gp there's nothing they can actually do.

We are at the other end of the dementia spectrum, it's a cruel horrible disease, in just glad that she had a "normal" life so far in because grandad covered for her.

We have a family situation caused by dementia so feel your frustration. I'd have a look online about support groups etc and tests you can try to sneak on them to avoid doctors, one is asking them to draw a clock. Ultimately, you will need a doctor and the sooner you get a diagnosis the better, as hard as it is.
Good luck x

Sorry to hear this OP. With my lovely MIL the obvious signs were she could no longer play very simple board games with the kids (think snakes & ladders with a 4 year old & FIL). She'd get confused, she didn't understand what she was seeing, she couldn't process the images or symbols. She also started sending cash gifts in birthday cards, having always been happy to use online banking and making transfers as gifts. Then forgetting birthdays and little things like Valentines (she always used to send her adult kids & grandchildren some cute silly token chocolates). Then she didn't want to use the dishwasher any more, it felt too complicatded. After FIL died unexpectadly about 1.5 years ago if became very obvious, he had been 'covering' for her, and my DH helped her get a diagnosis. She's still OK on her own with a lovely cleaner a few times a week who also takes her food shopping and to the hairdresser etc, but we can see this won't last sadly. Her world is shrinking. She's still all there in a sense, and not a danger to herself, cooks simple meals and showers, but she struggles with short term memory and often can't remember our youngest DC. It's very sad.

P.S: This started in her late 60s. We live 2 h away.

It could be lots of things including normal aging. If you can manage to talk to her in a calm way when she is not in one of the situations you describe and see if she is concerned at all. It depends on where you live as to the diagnostic route but a GP is a good start. You can talk to the GP yourself about your concerns but he or she cannot get into a discussion with you. If it turns out this is the early stages of dementia then there are drugs that treat the brain function but as yet there is no drug therapy for dementia. It is a good idea to get other things ruled out. I would google the dementia diagnostic pathway for your area. Also contact the Alzheimers Society who do much to support families and have a helpful website. Good luck

I had a very helpful chat with a dementia advisor this week. Definitely get in touch with someone like this & have a quick chat.

What is normal aging though? DM is obsessed with the TV she puts it on in the morning and sits in front of it, I do put on some music she likes but often she says she wants 'peace and quiet' and puts on the telly over the music! She reads the newspaper but not books that she used to love.

She refuses to have any one else in her flat (warden assisted) dsis and I share her care, she refuses to wash up or do her washing etc. Oh and she goes shopping with dsis and unless properly guided she keeps buying food that she won't cook, it's so wasteful and sad because she used to love cooking and was a good cook.

I’m sorry you are going through this op.
With my mother the first signs were loss of empathy and humour, both of which she’d had in spades.
She was rude to people having been the politest person I knew.
My df was an alcoholic and my dm put up with his abuse for years and years (largely because she feared if she went the family business which she ran would go bust). I sometime wonder if her personality change was due to the edit facility in her brain failing and years and years of pent up anger came out.