“Cognitive decline”: Is Donald Trump sick? Top psychologist sees “first signs”. “I view this cognitive decline as further danger to an already volatile, mentally challenged individual who should not be anywhere near the White House,” said Cornell University psychologist Harry Segal.
Trump's mental deterioration occur "sporadicly," according to Segal, and typically manifested themselves during late-night appearances. The expert also claims to have noticed that the complexity of Trump's language has changed.