I face the same problem. Have they done a brain MRI on him. If not, insist on one. The positive result woke my provider up. They still haven't done much more. The coroner for my mother gave vascular dementia as the cause of death--that helped. Out of frustration, my family doctor put me on Aricept which has been a great help, but I have also tested positive since then on an amyloid PET scan (my grandmother's diagnosis was Alzheimer's) so I don't know what is going on. In frustration I have had my neurologist refer me to Mayo and am now waiting for a response. I should mention that I am almost 83 and have had adverse reactions to around 55 medications, to date. I have had autoimmune problems since the 3rd grade. Good luck! I look to Mayo for better guidance and diagnosis than I have gotten in Idaho (which is almost nothing).