What is a cognitive test and can it really tell us if Biden, Trump are mentally fit?

Joe Biden and Donald Trump are, respectively, the oldest and second oldest presidents in American history. As both attack each other over their mental acuity in the 2024 election, they have also fielded calls for cognitive tests because of their age.

After a stumbling debate performance by Biden in which he seemed hard to follow and would lose his train of thought, concerns about his age and mental fitness have ratcheted up.

In a Friday night interview with ABC’s George Stephanopoulos, Biden, 81, refused to commit to taking a cognitive test. “I have a cognitive test every day,” said Biden, who would be 86 when he leaves office if re-elected in November.

Trump, 78, also faced questions about his cognition when he was in office. In 2018, his White House doctor, Ronny Jackson, now a Republican congressman, said Trump took the Montreal Cognitive Assessment, or MoCA, a common and quick test used by health professionals to help identify dementia or cognitive loss. Trump had a “normal” score of “30/30,” Jackson said. Trump said he “aced” it.

In January, Trump, who would be 82 by the time he leaves office, boasted that he had again aced the MoCA test, adding he had to point out a whale among animals with questions getting progressively harder. However, the test doesn’t include a whale, MoCA’s developer, Dr.  Ziad Nasreddine, told the Washington Post.

The MoCA test only looks for minimum cognitive faculties, not someone’s rigor. In other words, MoCA is supposed to be easy for someone who has no cognitive impairment, Nasreddine previously told MarketWatch.

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What do cognitive tests do?

Cognitive tests can assess mental awareness, reasoning and memory. Cognitive tests are not for gaffes, as Biden and Trump have been prone to make. Biden has had a stutter his entire life, which impacts his public speaking, but not his cognitive ability.

The tests are usually conducted if people show signs of mental decline or impairment of oneself, family or friends, according to the Cleveland Clinic. The tests don’t require preparation or study. They are meant to be quick and basic.

Early detection of cognitive decline can help identify treatments or lifestyle changes that can slow decline, according to the Alzheimer's Association.

What kinds of tests are there?

MoCA, the 15-minute test Trump said he aced, involves memorizing a short lists of words, naming objects in pictures and copying shapes in pictures. In addition to MoCA, other tests include the 10-minute Mini-Mental State Exam, which requires the test-taker to count backward, identify objects in the room, stating the date and other “common, well-known facts,” according to the Cleveland Clinic.

The Mini-Cog is the shortest and easiest to complete at three minutes. It includes memorizing and recalling a three-word list of unrelated words and drawing a circle clock with time points and then showing the hands for a specific time.

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What can't they tell us?

It should be noted older people’s brains perform differently than younger people's, Dr. Alvaro Pascual-Leone, a professor of neurology at Harvard Medical School, previously told USA TODAY. So while there is heightened risk of brain disease with age, he said, there are strengths and weaknesses at every age. Young people can learn new facts more quickly, for example, but elderly people can put those facts into the big picture, what's typically called "wisdom," he said.

Additionally, people shouldn’t rely on a single snapshot that might miss a high-functioning person’s decline.

A cognitive test, such as MoCA, has results online, so someone could study ahead of time. That’s why it’s important for brain health screening exams to be given routinely starting in middle age, several experts told USA TODAY, to show changes that may signal decline even in someone who can "ace" the tests.

However, the publicly available summaries of both the president's and former president’s annual physicals did not include cognitive testing.

This is reflective of the public more broadly: Most doctors do not perform cognitive testing on their older patients, even though most people say they'd like to get screened to better detect brain disease early, Pascual-Leone said.

“There is a huge gap between the expressed desire and need, the awareness by clinicians and the reality of what is being done," he said.

Are cognitive tests a good test for presidential fitness?

Readily available cognitive tests are not a great gauge of fitness for the rigors of the presidency, experts told USA TODAY.

There isn’t a perfect way to judge someone’s mental fitness for office, Jamie Reilly, a professor of speech-language pathology and neuroscience in the College of Public Health at Temple University in Philadelphia, previously told USA TODAY.

Biden noted during his ABC interview that he proves his fitness for the job of president every day.

Accusing either candidate of having dementia or lacking mental competence may score political points with some voters but could worsen existing stigma against older people and prevent those with legitimate concerns about their memory and language from seeking help, he said.

Karen Weintraub and Jeanine Santucci of USA TODAY contributed to this report.

This article originally appeared on USA TODAY: Can a cognitive test tell us if Biden, Trump are mentally fit?