One man thinks the Second World War may soon start; the other can’t remember who the leaders of France and Germany are.
Both are running for US president, an all-consuming and sleep-depriving job often described as the hardest in the world.
Joe Biden, 81, and Donald Trump, 77, are the presumed nominees for the Democrats and Republicans in this year’s general election, leaving Americans to choose between two candidates who are well past their prime.
Each is making gaffe after gaffe, raising questions about their fitness for office and whether they can function properly at the helm of global affairs.
A Quinnipiac University poll published on Wednesday found that most Americans think Mr Biden and Mr Trump are both too old and mentally unfit for the White House.
The issue is particularly acute for Mr Biden, who is already the oldest president in US history. If he is re-elected on November 5, he would be 86 at the end of his second term.
According to the poll, 67 per cent of voters think he is too old to effectively serve another term, compared with 57 per cent for Mr Trump.
Barely a day goes by without Mr Biden making some sort of slip – verbal or physical.
A recent news conference in which he tried to refute his image as a “well-meaning, elderly man with a poor memory” only made things worse.
The description came from Robert Hur, a Republican lawyer who said Mr Biden mishandled classified documents after he left the vice presidency in 2017. The former prosecutor said in a report that charges should not be brought because jurors would feel sorry for Mr Biden due to his age.
At a news conference that day, a defiant Mr Biden told reporters that his “memory is fine”.
Then, moments later, he mistakenly referred to Egyptian President Abdel Fattah El Sisi as the leader of Mexico.
Republicans seized on the blunder as another example of what they say is Mr Biden’s diminishing mental acuity.
The issue has gathered so much attention that even the liberal-leaning New York Times published an editorial questioning the US President’s “cognitive sharpness and temperament”.
But even as Republicans attack Mr Biden for his age, they studiously avoid discussing the cognitive issues their candidate, Mr Trump, who turns 78 in June, is encountering.
In a recent speech, he said Mr Biden is “cognitively impaired”, before warning that the President could start “World War Two” – which ended in 1945.
He called Hungarian Prime Minister Viktor Orban “the leader of Turkey” and repeatedly confused his Republican challenger Nikki Haley with former Democratic speaker of the House of Representatives Nancy Pelosi.
Last month, he devolved into speaking gibberish at a rally, saying: “We can’t do anything. We are an institute in a powerful death penalty. We will put this on.”
Not to be outdone, Mr Biden this month confused the late German chancellor Helmut Kohl with former chancellor Angela Merkel, and French President Emmanuel Macron with former French leader Francois Mitterand, who died in 1996.
Ms Haley, 52, who trails Mr Trump distantly in polls, this week highlighted some his lapses and alluded to his increasing use of Nazi-like rhetoric, saying he is becoming “more unstable and unhinged”.
Not only is he running for office, Mr Trump is also simultaneously fighting four federal criminal indictments, and recent civil cases have found him liable for sexual assault and fraud.
Dr Sandi Petersen, vice president of health and wellness at Pegasus Senior Living and an expert on ageing, said Mr Biden is a victim of stress and time.
“The continued stress of the role and the even more stressful campaign trail will not be kind to him in terms of his ability to lead, think critically and meet the daunting challenges of the future in the country,” Dr Petersen told The National.
“I think the recent memory lapses are symptomatic of this decline and may represent a threat to his ongoing well-being, as well as his ability to lead effectively.”
The assessment is not much better for Mr Trump. The former president last month bragged about a cognitive test he took while in office, boasting that he was able to correctly identify a whale among a series of other animals.
“When one considers his legal and financial troubles, as well as the stress of campaigning, is it any wonder that the stress levels he is enduring would result in lapses?” Dr Petersen asked.
“The body, as we age, is hypersensitive to rising cortisol [a stress hormone] levels.
"Both Biden and Trump, from both physical and mental health perspectives, are undoubtedly under the influence of stress hormones that affect both memory and mood.
“That, coupled with the normal response to ageing, will not bode well for them in a highly visible, highly stressful role.”
The presidency requires frequent international travel across time zones and chronic sleep deprivation makes it harder for people to retrieve information, especially newer memories.
“People who are put in a position where they are not able to consistently get restorative sleep, if that's something they need, can have reduced ability to attend, can look like they're not paying attention to what's going on and could potentially look like they're not able to remember what has been immediately said to them,” Dr Christina Prather, director of George Washington University’s division of geriatrics and palliative medicine, told The National.
The US public should not only be concerned about the two candidates’ minds. Dr Prather said there was the “very real possibility” that either could suffer a health crisis.
“Anyone's ability to withstand a major health event as they go into advanced age is entirely personal but also is reduced as someone ages,” she said.
But getting older is not all doom and gloom.
“Over the course of a lifetime, our reactivity often decreases and one's life experience favours more rational and less reactive decision making,” Dr Prather said.
“That is what we should be looking for … their ability to do the position, not necessarily their numeric age.”
