I meant to add, they also will interview you and any other family members who can be available for an in-person discussion. That helps elicit details about behaviors and thoughts that you might not ever see because your'e not always around.
Depending on your dad's symptoms, if you think he probably has dementia, the first step you could take would be to have him see a neuropsychologist. NP's aren't the same as neurologists. They don't look at physical structures at all, just mental health/symptoms. There is a memory deficit assessment that takes about three hours and is very detailed. From that assessment they can tell you their best estimation of what your dad is facing and how likely they think it is to progress. NP's also aren't psychiatrists. They can't prescribe any medicines for your dad, but they can tell you generally what options exist, which you can then hand on to your dad's doctor. Hope this helps!
I often would mail or fax my mother's neurologist an update right before an appointment. Sometimes, he would meet with me before coming into the room to talk with my mom.
However, you do it, let the doctor know your observations! Elderly patients try very hard to come across healthier than they are.
You know Dad better than anybody does, even the MD. Patients are very good at hiding their deficits. MD's have to learn to read between the lines. Go with him to the MD office and stand behind Dad but facing the MD. When Dad tells a fib, just shake your head "No" and say nothing. Let Dad do all the talking and the MD will pick up on your cues. It works.
However, you do it, let the doctor know your observations! Elderly patients try very hard to come across healthier than they are.