"Whether he realized it was an interview or not, I don't know, but it certainly was not off the record", said Wolff. "I had a situation where I was a very excellent student, came out, made billions and billions of dollars, became one of the top business people, went to television and for 10 years was a tremendous success, as you probably have heard".
Mr Bannon, who was sacked in August, was quoted last week quoted in a newly released book Fire and Fury: Inside the Trump White House as saying a June 2016 meeting with a group of Russians attended by Mr Trump Jr and his father's top campaign officials was "treasonous" and "unpatriotic".
He added: 'I consider it a work of fiction and it's a disgrace that somebody's able to do something like that'.
Trump said he had gone from being a successful businessman to TV star to president of the US.
Its author told NBC's Meet the Press he spoke with the president directly several times, but said that Mr Trump might not have been aware they were interviews.
Mr Trump angrily responded to the publication of the comments on Thursday, saying Mr Bannon had lost his mind, while the White House suggested the hard-right news site Breitbart News should part ways with him as its executive chairman.
'That's why Sloppy Steve is now looking for a job, ' he added.
Reagan, the Republican US president from 1981-1989, was diagnosed with Alzheimer's disease in 1994 and died in 2004.
"This morning you were tweeting about your mental state", a reporter began. At times when he was president, Reagan seemed forgetful and would lose his train of thought while talking.
Nikki Haley, the US ambassador to the United Nations, said that she is at the White House once a week, and "no one questions the stability of the president".
Reagan was almost eight months younger.
Bannon walked back many of his remarks on Sunday about the Russian Federation investigation, Trump, and his family.
Bannon praised Trump on Sunday, saying he was the only candidate who was capable of defeating "the Clinton apparatus", referring to Hillary Clinton and her husband, former President Bill Clinton.
"I tried to be inobtrusive", he said.
The president wrote in a tweet this week that he feels "Michael Wolff is a total loser who made up stories in order to sell this really boring and untruthful book".
"That's kind of why he does it".
Theresa Maywas asked about accusations in a new book that he is mentally unfit for office.
Trump is to undergo the first physical examination of his presidency on January 12.
This exam does not typically involve having the president undergo a mental health evaluation, as some Democrats have urged.