(NewsNation) —  President Joe Biden, 81, and former President Donald Trump, 77, are both under the microscope for recent gaffes and memory mix-ups.

The mental fitness of both candidates has become a major storyline of the 2024 campaign, including repeated mentions of age limits and competency tests. It has also sparked conversation about the best ways to keep brains from aging.

Dr. Tom Pitts, a board-certified neurologist, explained Monday on NewsNation’s “Morning in America” that over time, humans lose their ability to clear metabolic debris and it accumulates abnormal proteins that shrink and wear down the brain. This process causes people to slowly lose their mental acuity.

To slow down this process, Pitts suggests eating fresh, unprocessed food, cooking more often, sleeping better and exercising. These four steps will help support mental fitness in the long term.

If a patient or family member of a patient had some cognitive concerns, Pitts said doctors would start with a sleep study and bloodwork to look for any deficiencies or unusual brain function. Competency tests are an option, but usually, an EEG is conducted to rule out seizure activity or any abnormal brain activity.

Neurological testing would be the most important test if there are cognitive concerns, Pitts said.

“Neuropsychologists test attention concentration, memory, speech, word retrieval, and they can tell if you are more on a mild cognitive age-related path or more on the dementia pathway and if you do have dementia, what kind it is and how severe it may be,” Pitts said. “It’s single-handedly the most valuable test for you.”