@EMH1810 my husband had a similar experience. He is considerably older than your father, I was already worried about him as he was developing habits which I now know to be typical of early Alzheimer’s disease. He was due to attend the memory clinic but he could function perfectly well, driving and leading a fairly normal life. He had memory problems and suffered from fainting occasionally but in February he collapsed at a dinner with colleagues and friends when I was not with him. I caught up with him in A&E where I was shocked to find him in dementia, there is no other word for it. I hardly recognised him as he had never been like this before. He stayed in hospital for a couple of days and was uncooperative, trying to leave and was persuaded to stay quite unlike his usual self. He has been diagnosed with mixed Alzheimer’s with some VD and although he is not the same as he was before, he has recovered to a certain extent and can look after his personal needs. He can no longer drive and although he has recovered from the hospital induced dementia, he has not returned to the way he was before. I do hope this helps and that your father recovers some of his abilities too.