Long time lurker but felt that I had to share my own experience here. My Grandmother (Mum’s Mum) lived with us and eventually she sadly developed dimentia . It was very gradual to start with (or we were slow realising) but once it was obvious it accelerated quite quickly to the stage where she wandered about the house ‘lost’ at night and she got confused and (understandably) frustrated about many things. That in itself wasn’t too big a deal but of course it progressed and sadly, the incontinence started soon after.
Before I say any more, I feel I have to explain how cool my Gran was - she was widowed during the Second World War when my Mum was just a toddler and she raised my Mum and her older brother on her own, she was an amazing lady and the best Grannie I could have had and seeing her brought so low was devastating to all of us, but especially to my Mum.
Gran would mess her bed, I would lift her out of it and carry her to the bath, bathe, dry and talc her and pop her into a fresh nightie while Mum stripped and changed the bed. Gran would be back in her bed for 5 or 10 minutes and she would have another accident. This went on for several years with no help or outside assistance whatsoever. Mum was exhausted with it all and ended up having a bit of a breakdown and I was supposed to be studying for my exams but Gran needed us 24/7.
I loved my Gran (still do) but latterly she didn’t even recognise me, she was the most mild mannered lady but she used to batter me in the face with her fists when I’d be trying to bathe her… because by this time she did not know who I was and thought she was being molested by a stranger.
I still feel like I'm betraying Gran by sharing this but I see that the OP has children of exam age too and I see similarities with my situation all those years ago.