My mother had been pretending to have dementia for 10 years. I allowed her appalling behavior because I thought she was ill, she was spiteful and mean, always wanting gifts or money. She made my 90 year old father's life a misery. Last summer she was in hospital 6 weeks, she has parkinson's and had uti. I would phone every day so she didn't feel alone, I would cry most days as she was so hateful. She was being discharged and I went ballistic at the discharge team, that my father wasn't safe with her home, I did a lot of research and demanded test results....team very quietly said there is nothing wrong with my mother, I was really stern... again nothing wrong with your mother.... I was furious and said next you'll be telling me that she is making it all up..... absolute silence....the penny dropped, of course she was, she has all my life been a mean, spiteful, attention seeking narcissist. They explained all the scans and blood tests, I felt sick, her nurse told me mum enjoyed being nasty on the phone and would laugh after, she would laugh about being spiteful to dad to me. I spoke to her carers who also confirmed no dementia, where had I got that idea....mum told me and I accepted it. She says my sister is a liar and thief, my brother and dad are bully's so I would spend hours on the phone calming her down being kind to a woman who beat and neglected me as a child. She thinks it's funny and the real kicker for me is my dad lied and went along with it as he got all the attention and pity from me for having to live with her. He also calls my sister a thief and both my siblings are after money, they have been heavily subsidized by my parents all their adult lives. At the age of 62 I now realize my siblings and parents are sick, they have been keeping secrets from me that have recently come out and I have had to go no contact and blocked all numbers. I talked to dementia UK who said many oldies do it for attention and to excuse bad behavior as it's such an easy con, I asked if Drs could be wrong, apparently not, the tests can not be manipulated by behavior. So yes people do it and it's really shocking and hurtful. My family are messed up and dysfunctional, for my own sanity I have had to walk away. In hindsight it was bloody obvious but it never occurred to me my whole family were lying. There isn't much you can do tbh, it's sick behavior and pretty disgusting considering what an awful illness dementia is and the suffering it causes.