Opinion | Trump Says He ‘Aced’ a Cognition Test. What Does That Tell Us?

President Trump said on Thursday that he “aced” a cognitive test administered at the Walter Reed National Military Medical Center.

Neither he nor the White House, however, would elaborate on any details about the test, leaving the public in the dark on how to evaluate his claim. But it’s a fair guess that he was given a routine cognitive screening test that doctors use all the time to check for dementia.

If that’s the case, let me give you an idea of what “acing” such a cognitive test might mean. One commonly used screen is the Mini-Mental Status Exam or MMSE. Ready to try it?

OK, tell me today’s date.

Now, spell “WORLD” backward.

Next, here’s a piece of paper. Write a simple sentence. It must have a subject and verb and make sense, like “Hey, this is not a very difficult exam to pass.” (The maximum score for this test is 30; a score below 20 usually indicates cognitive impairment.)

You get the idea. These cognitive tests are basic and, unless you have dementia or some other medical or psychiatric problem that would impair your cognition, you, too, will likely “ace” any of these tests. If Mr. Trump wants to impress the public with his cognitive prowess, perhaps he should take the SAT.

I doubt that Mr. Trump will see it this way, but by bragging about his cognitive abilities, he’s asking us to consider what to expect, cognitively, of older people — and what cognitive attributes matter most in a president. After all, he and his likely challenger, former Vice President Joseph Biden, are well into their 70s, and their cognitive function is unlikely to be what it was in their 20s. And for a very good reason.

Just like the heart, kidneys and muscles, the brain ages and typically loses some function, something that scientists refer to as normal cognitive aging. Which is to say that you are not as mentally fast or agile at 75 as you were at 20. Your short-term memory is also probably not the same. And, at 70, you are probably not going to outperform your 17-year-old self on the SAT — or any test that requires fast reasoning. Not that you care, since you aren’t applying to college.

Yet, if you peer inside the brain — it’s easy to examine neurons under a microscope in a post-mortem exam — you will find that with age people don’t lose too many neurons in the prefrontal cortex, the brain’s executive control center and reasoner-in-chief.

The prefrontal cortex makes it possible to think strategically, consider the possible consequences of any actions, control impulses and plan for the future, among many other things. Yes, some large neurons shrink as you grow older, but few are lost.

Move over to the hippocampus, the region that is critical to memory, and you see something striking. Although the number of neurons doesn’t change much with age, the number of connections — or synapses — among neurons decreases substantially. And it is probably this loss of synaptic connectivity that correlates with memory loss, the most common age-related cognitive problem. Starting at around age 55, the hippocampus shrinks on average about 1 percent to 2 percent each year, something that may be potentially reversible with activities like exercise.

But the good news is that as we age, so-called crystallized intelligence — our knowledge and skills — stays pretty much preserved, even if fluid intelligence — our ability to solve novel problems — declines a bit over time.

Which brings us back to the cognitive functions that matter most in a president. Being president isn’t like taking the SAT — coming up with the best strategy to a Russian threat doesn’t need to happen in five minutes. Being president is more about having superior executive function: accumulated knowledge, judgment, empathy and wisdom. These are far more important than glibness or speed. The presidency requires the ability to be open to argument and challenge and work well with others.

(The president no doubt will attempt to portray Mr. Biden, well known for his verbal flubs, as somehow not cognitively up to the job — despite the fact that Mr. Biden has always had this tendency, so it’s very unlikely to be a cognitive impairment of any significance.)

So did President Trump really “ace” his cognitive exam? Perhaps. But if so, it’s a good bet that it didn’t assess executive functioning.

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