Veteran journalist and Donald Trump biographer David Cay Johnston weighed in on the president’s mental health and fitness for office in an interview with The Intercept published Thursday.

According to Johnston, Trump is a “clear and present danger” to the United States, and to the world. The journalist — who has been covering Donald Trump since the 1980s — said that Trump believes that he is genetically superior and smarter than everyone else, which is why he has long held the belief that he should be running the entire world, and not just the United States.

“Donald has always been deeply mentally ill. He literally believes that he should be running not just the U.S. but the whole world, that the rest of us are all fools and idiots, and that he is genetically superior.”

Johnston explained that the Trump family believes in the “horse race breeding theory of genetics,” which is why the president frequently claims to be an expert on various subjects he is actually not at all familiar with.

The bigger danger, according to Trump’s biographer, is the fact that many of the president’s supporters believe that he is indeed an expert and the fact that the majority of Americans — unlike Canadians or Europeans, for instance — do not have critical thinking skills.

Johnston also suggested that Donald Trump might be abusing drugs. The journalist noted that he has no proof to back up his claims, but explained that the president’s behavior — during the 2016 presidential debates, for example — indicates that he may be on drugs.

There has never been a president quite like Trump: the all-caps tweets; his obsession with election results and crowd sizes; his bragging, his boasting, his childish point-scoring. https://t.co/kpkNRotx0s — The Intercept (@theintercept) February 21, 2019

“He often talks like somebody who seems to be under the influence of drugs beginning with his repeated sniffling during one of the presidential debates to when he goes off in sing-song fashion as he did in the Rose Garden a few days ago,” Johnston said.

The journalist added that he thinks Donald Trump’s mental health has deteriorated, along with his cognitive abilities, claiming that the president is no longer capable of “keeping together a long string of thoughts.”

Johnston also discussed Trump’s closest allies, like Vice President Mike Pence, opining that none of them are stepping up and opposing the president or his agenda because Trump has surrounded himself with yes-men who are not willing to stand up to him. None of them, Pence included, are qualified for their positions, according to the journalist.

The writer concluded the interview by explaining that Donald Trump lives in his own parallel reality, that he “never learns anything,” and doesn’t care for objective facts.

“Donald has a completely unstructured mind. He never studied. He never learns anything,” he said.

David Cay Johnston is not the first person to publicly warn about Donald Trump’s allegedly deteriorating mental health and unfitness for office. As detailed by a previous Inquisitr report, Yale psychiatrist Bandy X. Lee has long urged that U.S. lawmakers seek help from mental health experts in order to properly deal with Donald Trump and counter his worst impulses.