"It is my opinion that both of the adults residing in the White House leave much to be desired when it comes to intellectual ability and cognition. I believe that I have posited plausible arguments at AT, e.g., here, here and here.
Now there is a scientific explanation providing validation.
First, a quote from FLOTUS:
"I am a believer there is a beet gene. People who love beets love them and people who hate beets can't stand them. Neither the President nor I have the beet gene..."
Second, the explanation and validation:
Daily Dose Of Beet Juice Promotes Brain Health In Older AdultsResearchers for the first time have shown that drinking beet juice can increase blood flow to the brain in older adults - a finding that could hold great potential for combating the progression of dementia. "