It`s difficult to know whether or not your nan realises she is being nasty or is able to control it. You don`t say if anything seems to trigger it.
My husband could be nasty especially if he felt afraid or unsure of himself or if he misunderstood a situation. It was difficult to work out why he was nasty so I just used to walk away and go into another room. Sometimes I made him a cup of tea and by the time I returned to him, the nastiness had gone.
If possible all I can suggest is you ignore your nan when she is like this. Trying to reason with her isn`t likely to work, not is discussion.
I do think you might try to work out if anything does trigger this behaviour.
Getting nasty is very common. Speak to who ever is responsible for her care, either her doctor or mental health team to see what help they can give her. Please keep posting as there is a lot of support and advice available from members of the forum to help you.
Thank you so much for your replies sorry I should have explained, she seems to get nasty when her partner has a break and she comes and stays with my mother until he returns home, only a couple of hours, but it's so hard as we think her partner needs a break xx
So you have found the cause. It is fear, insecurity being away from her partner and in a different house. She will not understand it is temporary.
Her partner does need a break but is there any way your nan can be cared for in her own home so she only has one change to manage, the fact her partner is away. That on its own is a force to be reckoned with.
Thank you breaking our hearts, knowing she is in her own home really will help I think, my mother doesn't want to tell her partner to stop his breaks as she be worried he can't cope and we work so it really is hard but are trying anything for her to stay at home, even thinking of giving up work but then there be the worry of bills etc xx
Try to find things to do that will distract Nan from fixating on her partner being missing. Tidying a drawer, making a cake ready for when he returns or preparing the veg. for lunch. There are lots of small jobs you can do, a chore is not so much a chore when you have someone to chat to while doing them.