@RM3, please be persistent about saying that your husband has changed significantly and set out what those changes are. I’m concerned that you are looking to be reassured that there’s nothing wrong but there clearly is (it may not be dementia). Bring a list of bullet points so that you don’t forget anything. It will be difficult to talk about your husband’s problems in front of him but if you don’t you may be told that there’s nothing wrong and your husband may be discharged from the memory service. You would then have to start from scratch if you wanted further or new investigations.
Remember that there are other scans that can pick up changes in the brain. Don’t forget to ask about them.
If the doctor thinks that this is just a MH problem e.g. stress, depression, anxiety then ask him/her what medication and lifestyle changes s/he recommends. Try to persuade the doctor to keep your husband ‘on the books’ as it were so that you can go back again if things don’t improve.
I hope that this consultation is productive.