Dr. Marc Siegel also said he was "concerned" about former Vice President Joe Biden.
Amber Ruffin reminded the president that his cognitive test isn't something to brag about.
Comic Sarah Cooper and others give Trump's cognitive test a new spin.
Person. Woman. Man. Camera. TV.
Dr. Ziad Nasreddine, inventor of the Montreal Cognitive Assessment (MoCA) test, said it measures cognitive impairment, not intelligence.
The "Late Night" host is putting Trump's bragging to the test.