Does it ever help to try an intervention-type discussion?
My mother-in-law is 83 and making my 89-year-old father-in-law batty. We can all see it coming: the repeating of the stories, the buying cheese (and apples and meat and whatever) every time she goes to the store because she forgot she bought them last time but forgetting the things that she does need, and the asking "What do you want for dinner?" three or four times before making whatever it is she wants to make. She is losing it.
Her best friend, when I called about something else, said that she would be on board for sitting down with her and my father-in-law and confronting her that she needs to go to a doctor to at least be evaulated and get a baseline test done. (This woman friend is normally a "hands-off-mind-my-own-business" lady. So I was shocked.) My husband says his mom is going to do what she's going to do and that she will totally ignore all of us until she forgets where she is one day when she's out driving. And then he says she will continue to ignore us. I feel that he is dodging the issue. But I also feel that confronting her will not do us any good either. But I really feel bad for my FIL.
My MIL says that he is making her take "stupid pills" because he thinks she is stupid. (He has managed to get her to take a few herbal supplements which won't do a thing, in my opinion.) I have no place in this discussion in a lot of ways because I am the daughter-in-law, but I also see that it will be my job down the road to deal with this woman as I work part time while my husband works full time plus overtime. So thanks for letting me vent. But, seriously, if all of us (her husband, her friends, the only son, the grown grandkids and another set of their friends) were to sit down with her, will it just be a painful waste of time? My FIL is going to put my husband on the bank accounts, but he's been putting it off.
Everyone else is in denial - MIL, FIL, hubby, etc... But that's normal. I did the same - hiding my head under the sand - for years. When I finally realized the situation, it was years into caregiving and realizing that this could go on for years and years. Mom lasted 20 years after her diagnosis. You're correct to start looking into the situation now before it's too late.
With FIL and the bank account, don't approach it as a doomsday solution. Because if he's in denial, by actually doing the bank account is admitting there's a problem. Make it something Positive. One day, you might not be able to go to the bank and hubby can do it for you. Oh, online banking is great. Hubby can set it up so that he keep an eye and make sure bills are being paid. Here's the bank statement, see what's happening with your money in the bank... etc... Make the joint bank account as something positive and not as an admission that one day his health would be so bad, that your hubby would take over. This is only because it sounds like they're in denial. If FIL was not in denial, he would have already done the joint bank account.
https://www.agingcare.com/topics/5/alzheimers-dementia
then look into what kind of resources may be available for them in your area (try the department on aging), if you want to be thorough you could cost out some agencies and assisted living places.
do they have any legal papers done with an attorney, like a will, POA or trustee?
is the FIL still pretty good as far as his memory?
also if she is still driving, that can be big trouble sorry :(