@jackic Hi, friend. This sounds familiar... lots of tests, no answers, etc. etc. Anyway, even at his age it is possible to suggest some possibilities. First, has he had a sleep study? Sleep Apnea? At that age I was sleeping less than an hour per night. Second, tests such as ANA, BUN, Ribosomal P Protein, sFLC would seem in order. The sFLC is usually thought of for much older folks, but a relative of mine would have flunked it at age 15. Good image work of lungs, heart, kidneys, thyroid, brain, etc., might pick up deposits of mis-folded proteins in the cerebrum, as mine did. Eyes Checked? Have you kept all his testing paperwork? Get it all together, and the two of you go over every note or comment, and make sure that everything the doctor said or questioned is noted. Lots of things get sort of tossed out into the air, and never make it to a dX assessment because the doc forgets or questions her or his own judgment. I have found, after 70 years of this, that the most valuable part of my memory has been the lab and consult papers we have kept. Now I have written them up, and made my own notes to help me and the docs think this thing through. You can see the result at https://bit.Ly/1w7j4j8 under "Amyloidosis Dossier". I would suggest you and your son do your own systematic study to try to come up with something. And keep trying. It has taken me 70 years to understand my dilemma.