Not a proud night for Trump.

A sad night for the United States.

That’s my take after watching the presidential debate, but I didn’t watch alone. I enlisted three experts on aging to share their observations. I was focused on a single question while watching President Biden debate former President Trump. At their advanced ages — Biden at 81, Trump at 78 — is either up to the task of running the country?

This has been a hot topic for months, with many people convinced that Biden has lost his mental sharpness. (Not that Trump’s mental state hasn’t come into question.) I asked my three experts not to do a political analysis, or to make a medical diagnosis, because as I’ve written more than once, that’s a complicated process that can’t be performed from a distance.

California is about to be hit by an aging population wave, and Steve Lopez is riding it. His column focuses on the blessings and burdens of advancing age — and how some folks are challenging the stigma associated with older adults.

What I wanted was their take on command, coherence, competence, composure, reason and skills of communication and articulation. Aging takes a toll, physical and mental, but you can be an old 60-year-old and a young 85-year-old because everyone ages differently.

Biden froze up early on. He failed to come up with a word he was fumbling for while speaking about the national debt, and he looked lost.

One of my experts, Dr. Zaldy Tan, director of the Memory and Aging Program at Cedars-Sinai, emailed to say a televised debate can be like a “cognitive stress test” and is “bound to bring about subtle, albeit normal, age-related changes in one’s mental agility.”

It seemed to me, however, that with a scratchy, weak voice and a sometimes-vacant look in his eyes, Biden might be in trouble.

He and Trump both seemed pretty agile though during one exchange in which they took off the gloves and went bare-knuckle.

“You have the morals of an alley cat,” Biden said, staring down his foe while listing a few of Trump’s many transgressions.

“I didn’t have sex with a porn star,” Trump insisted, and if there’s a political campaign button with that claim on it, I’d like to buy a bushel of them.

The candidates took turns accusing each other of being criminals, which made me think back on another low point in American politics, when Richard Nixon insisted, as his presidency was in flames, “I am not a crook.”

Former President Trump and President Biden took turns accusing each other of being criminals during the debate.

(Gerald Herbert / Associated Press)

Another of my debate watchers was Dr. Myron Shapero, an urgent care physician in Beverly Hills. I wanted his perspective because he’s older than either Biden or Trump by a good stretch. Shapero is 90, and he thought Biden did not have a good night.

“I think it’s obvious that Biden is not Biden anymore,” said Shapero. “What Trump needed was someone sharp, sure, strong, who could counterpunch … and Joe always had that capacity.” On Thursday, “he didn’t have it.”

Shapero said the word that came to mind, as the night wore on and he studied Biden’s performance, was “flustered.”

“It’s the aging process, and everyone handles it differently,” said Shapero. “He was vacant. He was not fully present, and it was painful to see.”

Dr. Tan was more forgiving in his assessment.

“Besides the speech impediment,” he said, referencing a longtime Biden affliction, “it is possible that he experienced mind wandering, more commonly referred to as losing one’s train of thought. The tendency to mind wander increases with higher stress levels, sleep deprivation and taking certain medications.”

Caroline Cicero, an associate professor in the Leonard Davis School of Gerontology at USC, said she saw a sitting president who was not at his best.

“Viewers surely noticed that President Biden did not command confidence in his performance,” Cicero said. “His blank stares left me wondering if his strategy was not to react and to stay stone-faced, so that he didn’t appear to be a grumpy old man.”

Cicero said she wondered why Biden at times did not respond “more directly” to Trump attacks. “Reaction times do slow with age,” she said.

Tanzella Young, left, Crystal Blakley and Jason Sanford watch the presidential debate at the M Lounge in the South Loop neighborhood of Chicago.

(Charles Rex Arbogast / Associated Press)

Early in the debate, when Biden trailed off, Trump said: “I really don’t know what he said at the end of that sentence. I don’t think he knows what he said, either.”

Trump went in for the kill, as Dr. Shapero saw it.

“Smelling blood made him nastier and more pathological,” Shapero said. “I feel that substance-wise, [Trump] was filled with lies, but stylistically, I think he came off stronger because he was less maniacal” than he usually is.

One can ask whether Trump, a man aggressively removed from truth and civility, is fit for office. And Biden scored some points in exposing his opponent’s many barnacles, including the fact that he’s a convicted felon.

But what I saw in Biden was a decent man and career public servant who is past his prime.

What I saw in Trump was the usual boast and bluster, with no apparent ability or desire to control his own worst instincts.

They ended the debate arguing about who had the better golf handicap.

Lord help us.

Steve.lopez@latimes.com