Though President Biden dismissed the suggestion, experts say having him take a cognitive exam has merit. Here's how the tests work, and what they might tell us.

This is the most recent time the former president has claimed to have passed a cognitive test, which experts say are simple exams meant to test for brain function problems.

Age-appropriate cognitive assessments have been done at five points, so far. The team found that looking at cognitive tests in infancy could predict about 13% of the variance in scores at age 30.

On the heels of President Joe Biden's lackluster debate, Fox News Digital spoke with leading neurologists to determine how cognitive tests work, as well as what they can and can’t identify.

Donald Trump not only received a clean bill of health during his physical exam, but the president claimed he also scored “the highest mark” on a cognitive test while bashing his predecessor.

Barack Obama’s former physician said a cognitive test would have helped the White House and the public understand whether Biden was up to serving another four years.