Thanks lot for posting your questions in this web site. The problem in elderly individual is generally difficult to handle and a given medical problem can have mutiple causes. Regarding your father, if you are very sure that the problem has started very recently, a medical condition called as delirium needs to be ruled out. This a medical condition which may present similar to your father, provided that the onset of illness is of short duration. As the causes of delirium are so many, your father would require blood tests to rule out any infections, altered liver funtions, kidney functions, CT scan or MRI scan of brain to rule of any tumor/stroke which may explain his problem. The second part of the story is that this illness might have started earlier in a less severe form and might have worsened now. If this is true, a possibility of dementia is high on the card. My advise will be to get the blood tests, liver and kidney function tests, serum sodium, thyroid function including MRI Brain. If all these tests are inconlusive, he may be subjecetd to a detailed neuropsycological evaluation to see if he has dementia or not and we can manage accordingly after establishing the diagnosis. The third part of the story in these types of cases is that a single patient can have both and if delirium is treated properly, he gets back to the previous state. Hope this will help you If your father is in India, they can contact me Best wishes