“We choose truth over facts,” former Vice President and 2020 Democratic nominee hopeful Joe Biden announced at the Iowa State Fair last month, much to the confusion of his supporters. This misquote is one of many gaffes that Biden has made on his current campaign trail. In addition to providing fodder for President Trump’s campaign, these moments have also led voters on both sides of the aisle to wonder if his age is impeding his ability to serve as a political leader.
Considering the effect of aging on the brain in healthy adults, it appears that these ruminations have legitimate scientific backing that should influence the way voters evaluate presidential candidates.
At age 76, Biden is not the oldest of the presidential candidates — that distinction goes to Bernie Sanders, who is 78 years old. Senator Elizabeth Warren, another front-runner, is 70. And in the last three years of his first term, President Trump, 73, has said plenty of nonsensical things, like referring to Tim Cook as “Tim Apple” and mixing up his grandfather’s birthplace with his father’s, that have compelled some people to wonder if he is in the early stages of dementia.
Senior rights activists are swift to label this kind of criticism as ageism, and it certainly appears that way on a surface level. However, the scientific evidence supporting cognitive decline in elderly adults shows that in presidential elections, age is a legitimate concern, not just unfounded bias.
The typical course of aging results in a trade-off between the two types of intelligence proposed by psychologist Raymond Cattell in the 1940s: crystallized and fluid. Crystallized intelligence, more commonly thought of as wisdom, is the accumulation of experiences, education and factual knowledge over the years. In contrast, fluid intelligence refers to one’s ability to problem-solve in unfamiliar situations, think analytically and learn new things.
As people age, their crystallized intelligence improves, but fluid intelligence peaks around age 40 and begins to decline soon after. For presidents, both types of intelligence are important — crystallized intelligence is needed to make informed decisions, and fluid intelligence is necessary for coming up with quick solutions in times of crisis. Because it is not possible to peak in both types of intelligence simultaneously, it is important for presidents to surround themselves with Cabinet members who possess the type of intelligence they lack.
Another neurological consequence of aging is the disproportionate loss of prefrontal cortex matter, a phenomenon that begins at the age of 60. As stated in a study by professor of neurology Mark Fisher at UC Irvine, the prefrontal cortex is the part of the brain responsible for executive functions like organization and decision-making.
Fisher’s study shows that while all areas of the brain show decreasing volume with age, the prefrontal cortex shows the greatest volume loss as a result of age. To clarify, this loss of executive function is the typical course for healthy individuals without severe age-related impairments like dementia. Considering that decision-making is perhaps the most important role of the president, this finding has significant implications for the older pool of political candidates.
An important factor to consider in the loss of the prefrontal cortex is the aspects of executive function that it affects. The same study by Fisher states that executive function also encompasses memory and communication, yet interestingly, these abilities are not impacted by the decline in prefrontal cortex matter. This means that even political leaders who come across as sharp in speeches and public appearances may struggle with rapid decision-making in the situation room. Thus, when electing leaders, it is important for voters to consider not just the appearance of candidates and their proposed policies, but also how well they will function in meetings behind closed doors.
Given all this evidence, it is worth noting that there are individual differences in aging, meaning not everyone experiences cognitive decline at the same rate. For example, there are protective factors that can delay or prevent its onset.
According to a review published in the Journal of the Formosan Medical Association, staying physically, mentally and socially active are scientifically proven ways to reduce the risk of severe cognitive decline. The same review also linked less higher education to a higher risk of dementia after the age of 60. Considering that presidential candidates meet all the above criteria, they likely experience less severe cognitive decline than the average senior citizen.
Despite the overwhelming evidence that age-driven cognitive decline plays a role in how well someone can serve as president, it is not a topic that is seriously discussed by the White House or the public.
While presidents do go through physical check-ups that look for cognition problems, they set too low of a standard for someone leading a country. These tests look for conditions like dementia and stroke-related problems, not symptoms of typical age-related cognitive decline that can impact a president’s problem-solving and decision-making capabilities.
Furthermore, these medical examinations come after a president has already been elected, and there is no legal requirement for the all the results to be made public or even for presidents to take them. Without this information, it is up to the voters to gauge how candidates perform on the campaign trail and whether or not they are mentally prepared to take on the decision-making roles that come with the presidency.
With the 2020 elections coming up, voters should factor in how age-related cognitive decline may impact their candidate’s ability to serve as president.
Jessica He is a senior writing about neuroscience. Her column, “Gray Matter,” runs every other Wednesday