My father has been on a drug trial which entail is affecting his memory, he sold his grandson a car & said he lost the title which in truth he still owes on a loan for it & the bank has the title, he has gotten rid of everything, he says people are doing or not doing things which the people in question do not even know about, he does not seem to remember anything etc..
He just turned 70, has a full time job & seems capable in all capacities , but it turns out, he is not seeming to be capable of things
He needs to evaluated by a doctor training in identifying dementia and Alzheimer's. This is really a medical question and your father needs to go through a series of tests in order to determine his cognitive abilities. If he is determined to be incompetent, you then will need to contact an attorney to set up a guardianship or conservatorship.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.