USSC Honorary Associate Dr Harry Melkonian speaks to The Nightly Five podcast about the concerns around President Joe Biden's cognitive health and the serious implications of this for the office of the presidency.

"Look, the president is someone who can get a phone call in the middle of the night from the airforce saying that a Soviet jet has entered American airspace, what do we do? And whoever the president is, has to be someone who is not confused. And who can make a rational, sound decision very quickly," said Dr Melkonian.

"There have been candidates in the past who have had bad debates," he said of the presidential debate.

"With the case of Joe Biden it was not that he wasn't well prepared or that he was tired, it was basically his mental condition - his cognitive skills that were scary."

"He can't turn himself into a middle-aged man again, is his problem."