Mr Trump and Stern had been long-time friends prior to the Trump presidency, with Stern often interviewing the now-president about the business endeavours of the Trump Administration.
In Stern’s interview with Cooper, the two discussed Mr Trump’s childhood, presidency, and everything in between.
Stern told Cooper: “From what I know of Donald and his relationship with his father, it sounds traumatic.”
“It sounds like the father was very domineering, the father expected a lot of him, and there was military schooling.”
The president, who grew up in Forest Hills, Queens, attended a private military boarding school.
Stern continued: “I can assure you he’s been traumatised. Donald, his level of narcissism is so strong. He has trouble with empathy, we know that.
“I wish he’d go into psychotherapy, I’d be so proud of him if he did.”
Cooper asked Stern what he thinks of Mr Trump being in the White House, given the pair’s history. Stern replied: “First of all, it’s unbelievable to me. I’ve documented my thoughts about how this whole candidacy even came about - this was a publicity stunt.”
Stern attributes Mr Trump’s presidential run to an attempt to drive up falling ratings for Mr Trump’s show The Apprentice. Stern claims that as Mr Trump was denied a raise, he went along for the ride. “What’s a better way to get NBC’s interest? I’ll run for president.”
Cooper then asked Stern if he thought Donald Trump enjoyed being president, which Stern gave a definitive no to.
But he added: “I think he enjoyed winning the presidency. He likes to win.”