It seemed like a sensible suggestion for assessing the capabilities of an 81-year-old man seeking voters’ approval to remain in the White House until January 2029.

To reassure the American people, ABC’s George Stephanopoulos asked President Biden, would he be willing to take a cognitive test and share the results with the American people?

Biden demurred. In carrying out his duties as leader of the free world, he said, “I have a cognitive test every single day.”

Though the president dismissed the suggestion, medical experts said the idea of having Biden — along with his 78-year-old challenger, former President Trump — take some kind of cognitive exam had merit.

“Let’s give it to both of them,” said Dr. Louise Aronson, a geriatrician at UC San Francisco.

Kevin Duff, a neuropsychologist at the Oregon Health & Science University’s Alzheimer’s Disease Research Center, likened the proposal to the long-standing practice of asking presidential contenders to release their tax returns.

There would be several types of tests to choose from. A simple screening exam could involve just a handful of questions and be completed in minutes. An in-depth evaluation could take a full day.

When former White House physician Dr. Ronny Jackson evaluated Trump in 2018, he opted for the popular Montreal Cognitive Assessment, or MoCA Test. Over the course of about 15 minutes, patients are asked to recall a list of five words, draw a clock with its hands set to a particular time, do subtraction with double-digit numbers, and come up with the names of animals in a drawing, among other tasks. At the time, Trump scored a perfect 30 out of 30.

Whether long or short, a good test measures multiple “domains of cognition,” Aronson said. There’s short-term memory and long-term memory. There’s the ability to communicate through both spoken and written language. There’s attention, comprehension, judgment, reasoning, problem-solving, decision-making and more.

“If a person completely aces a test, that tells you something,” said Dr. Laura Mosqueda, a professor of family medicine and geriatrics at USC’s Keck School of Medicine. “And if they bomb a test, it tells you something.”

A score that’s somewhere in between can be trickier, experts say.

An abnormal result on a cognitive test doesn’t necessarily mean that a patient has a true cognitive problem. In about 10% of cases, it can be chalked up to a side effect of medications, an infection, a thyroid problem, a vitamin deficiency, a mood disorder such as anxiety or depression, or something else that’s reversible.

“The thing we see constantly as geriatricians are medication reactions,” Aronson said. “I can’t tell you how often we withdraw medications and then the person goes back to normal.”

Sometimes it’s even simpler than that.

“I’ve seen people diagnosed with dementia who’ve actually had a hearing problem but didn’t want to admit it,” Mosqueda said. “They couldn’t hear the questions and so they were giving weird answers.”

Some cognitive changes are a normal part of the aging process. Thinking speed is a prime example.

“As we age, we will do things more slowly,” Aronson said. That isn’t necessarily a sign of cognitive impairment, she said, recalling a 101-year-old patient who missed only one point on a test but needed extra time to complete it.

If a patient’s cognitive problems persist, or if caregivers want to get a better handle on the subtleties of their condition, a more in-depth assessment may be in order.

The tasks are more challenging, Duff said. For instance, instead of seeing whether a patient can remember five words after five minutes, a neuropsychologist might give a patient 15 words and see how many they recall half an hour later.

On the MoCA Test, a score of 25 or lower is considered abnormal regardless of any other factors. With a more sensitive test, the results are compared with the performance of other people of the same age, educational background, career history and other characteristics, Duff said.

A person with Biden’s background would probably perform well on a MoCA test even if his cognition has declined, experts agreed.

“In certain patients who are particularly verbal, they won’t remember the word they want but they can work their way around it,” Aronson said. In such cases, a normal score on the test “would not necessarily rule out cognitive impairment.”

Duff said it would be like having an IndyCar driver who wants to compete in the Indianapolis 500 take the same behind-the-wheel test that the DMV uses for 16-year-olds.

“My concern is that a relatively easy test still doesn’t mean you’re up to the challenge of leading one of the most powerful countries in the world,” he said.

This isn’t an issue limited to presidential candidates. It may be appropriate to ask airline pilots, bus drivers, surgeons and other people with jobs that entail a high degree of responsibility to take cognitive tests as they get older, experts said.

“I think you can argue this is a job where your brain should be working pretty well,” Aronson said.

There is no expert consensus on whether to screen all older adults for cognitive impairment. The U.S. Preventive Services Task Force weighed the issue in 2020 and determined there wasn’t enough evidence to make a broad recommendation one way or the other.

One of the reasons for the hesitation is that screening tests aren’t good enough, said Dr. Colleen Christmas, a geriatrician at the Johns Hopkins School of Medicine.

“You’re going to catch a lot of people who don’t have issues, and you’re going to miss a lot of people who do,” she said.

There’s also the fact that the aging process varies greatly from person to person.

“It’s incredibly heterogeneous,” Christmas said. “There’s no way to say 80 equals old whereas 75 equals young.”

Besides, no test, no matter how sensitive, can provide a full picture of a patient’s cognitive function. Doctors also need the results of blood tests, brain scans, and information from family members, among other things. If an MRI revealed evidence of several small strokes in parts of the brain that align with the patient’s cognitive deficits, for example, it would suggest a diagnosis of vascular dementia.

“It’s like putting a puzzle together,” Mosqueda said.

Biden may be in a unique position, but his bristling reaction to the idea of taking a cognitive test was pretty typical, Christmas said.

“I think people are so afraid of the diagnosis of dementia that it’s upsetting to have your doctor or a family member suggest that you need cognitive testing,” she said. “It’s a really scary prospect.”