American President Joe Biden is now 80 years old, and in the next presidential election in November 2024, he will be nearly 82. Four years later, near the end of what could be his second term, he will be 86.

That’s nudging 90. Hence, the question — is there an age beyond which no one should be allowed to run for president? 

Is there a time beyond which humans simply aren’t up to snuff, cognitively speaking, for incredibly demanding jobs such as the presidency of the United States, presidents and prime ministers in other countries, cabinet ministers and supreme court justices?

Biologically speaking, the numbers aren’t encouraging.

The risk of significant cognitive impairment rises steeply much past 80 and is not uncommon in the 70s, whether from Alzheimer’s disease, frontotemporal degeneration, Lewy body dementia, cerebrovascular disease or combinations of any of the above – never mind common, natural age-related senescent changes affecting the brain. 

The results are various functional changes. Older people walk slower and are more prone to stumbling and falls.

They also tend to talk slower and don’t process information with the same speed and fidelity as they did in their younger days.

Memory begins to fail for names and past or upcoming events. I share some of those pitfalls and know others of my generation who are only too aware of their own cognitive failings.

These familiar observations are signs the brain isn’t as sharp and reliable a tool as it used to be.

Compounding these increasingly challenging cognitive issues is the fact that older people tend to tire more readily and find it harder to concentrate and focus on tasks at hand.

It’s not enough, perhaps, to meet diagnostic criteria for mild cognitive impairment but is nonetheless significant and a common prologue to clinical dementia.

Paralleling the foregoing behavioural and performance declines are progressive structural changes in the brain such as atrophy, neocortical thinning and ventricular enlargement. 

Although Biden is said to have had a speech impediment for years, his tendency to mumble and say the wrong thing except in carefully scripted speeches with the teleprompter in front of him, or when he has notes close at hand, seems to be more common as he ages.

Like most presidents, he has highly competent staff nearby to help him out, but I wonder what happens off-camera.

That doesn’t mean Biden’s presidency hasn’t been effective – it has. In his first term, his administration passed important new legislation such as the bill on infrastructure.

But success in achievements, such as that bill, tends to be collaborative by nature and reflects the contributions of a team, of which the president is the ultimate head but not the author of the details on which the success of so many bills depends.  

I worry too because, like Ronald Reagan before him, Biden might be developing significant cognitive impairment, which might impair his judgement in the coming years.

What later became frank clinical signs of Alzheimer’s disease in Reagan probably developed two to three decades earlier based on what we’ve learned over the years from PET scanning studies.

They reveal amyloid and tau accumulation long before “obvious” clinical manifestations develop, such as mild cognitive impairment.

Presidents don’t have to be in their 80s to have cognitive issues. By 1944, former U.S. president Franklin Roosevelt was a shadow of his former self and not up to the job at the Yalta conference of negotiating with Joseph Stalin, former premier of the Soviet Union, about post-war Europe.

Former prime minister Winston Churchill had a history of ischemic heart disease during the war and several strokes in his second term according to his physician.

Or, what about former president Lyndon B. Johnson, who had two severe periods of depression, serious enough to warrant quietly stepping back from his responsibilities, while others managed for short periods, including his wife Ladybird whose diary published after her death revealed the details. 

Surely, it’s in the best interests of the countries they serve to impose age limits on the presidency and other key leadership positions in cabinets, senates, parliaments and the courts. 

It’s not simply a matter of whether Biden, who I’ve chosen to highlight the problem, is competent now to fulfill the responsibilities of his job. It’s whether he or others like him will be able to continue to do so throughout their terms.

If they can’t, what mechanisms are there for monitoring competency and removing those who are no longer cognitively competent to do their jobs? 

Given the aging of so many Western countries and other countries such as Russia and China and their leaders, these are not light matters.  

Leadership at high levels requires attention to biological competencies, as well as others, to serve.

Given the risks of misjudgement these days, those in power need the necessary cognitive skills, emotional maturity, energy and stamina to do their jobs effectively as a prerequisite for serving their country.

For those reasons, it makes sense to impose a limit of 80 years of age, beyond which candidates cannot serve. 

Do you want the pilot and co-pilot in the cockpit of the commercial jet flying you to Europe or Australia? At least pilots have mandatory rest periods. Presidents do not.

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the InfoHealth series at the Niagara-on-the-Lake Public Library.