Like everyone else here, I have no secret knowledge of him and I am reluctant to mock anyone, even him, for disabilities they can't control. My own uninformed guess is that he has the acquired laziness and corresponding impatience that comes from a lifetime of having every whim catered to. I suspect he has average (certainly not exceptional) intelligence and ordinary reading comprehension but usually can't be bothered because he can rely on others to do the demanding things for him. It does appear that age and neglectful lifestyle are cutting into his cognitive abilities. I think he is probably exhibiting signs of dementia.