I'll post a little about my dad. What I gather from reading about other people's experiences, after the early stages, the symptoms/behaviours are quite similar amongst the different types of dementia.
Initially (before diagnosis) my dad seemed to be acting very strangely. He wasn't forgetful but he'd do things that were very out of character - buying things from people selling door to door, accusing people of stealing, becoming angry at perceived slights etc.
He became very bad with money, he lost a few £k to a PPI scam, became paranoid that he couldn't afford to do his weekly food shop etc.
Socially, he became more withdrawn, especially in large groups. Eventually we found out that his colleagues at work had been covering for him. He hadn't been doing his work or supervising his staff properly. He became very anxious about work when he got a new boss who wasn't familiar with him. (His colleagues were well intentioned, but ultimately this may have delayed his diagnosis)
Gradually he became more and more forgetful. When driving he needed directions in areas where he'd lived/worked most of his life, forgot/became confused about which year/month/day it was etc.
He couldn't make food for himself any more. He struggled to make tea or coffee and an attempt to make himself a ham and cheese sandwich resulted in coffee grounds and sugar amongst the filling. He drove my mum round the bend a few times when poured orange juice into the milk.
He stopped washing himself, no showering, no brushing his teeth or wearing clean clothes every day. He seemed to struggle to get his words outs/explain things.
He took 3 weeks off of work over christmas (one more week than he was supposed to) and when he went back it took him over 4 hours to get drive home from work (his normal commute was ~45mins). That's when my mum took him to the GP and had him signed off of work.
He had been going to the memory clinic every 6 months for a few years by this point, but leaving work seemed to really push the consultants for a diagnosis.
In the two and a half years since his diagnosis, he has deteriorated very quickly. Within a year of diagnosis he had started going to the toilet (number 1) in his bedroom. Struggled to get even basic sentences out, lost the ability to understand even basic concepts. Had accidents with number 1&2, became more aggressive and violent, refused personal care etc.
ETA: He also tries to eat/drink non food items, e.g. cleaning products, so these need to be locked away from him.
He attended a day centre run by Age UK for almost a year until he had to leave due to too many violent incidences. Before he went to a retirement club until he walked out and was found by the police after being reported missing.
He has probably needed full time care for a long time now. We hope to have a place for him in a good care home within the first few months of the new year.
From what I gather his quick deterioration is pretty abnormal.
