Not so long ago a group of psychiatrists broke new ground. The team of experts declared, publicly, that President Donald Trump has a “dangerous mental illness”. An illness which may make him unsafe to lead the US. New concerns suggest that he may have dementia.

Now don’t get me wrong: no one should be stigmatised for disease. Would such a measure lead to harm, be misused and become political? Probably. Would you declare your opposition insane just to keep them out of office? Perhaps. But equally, can we afford to ignore clear signs of illness in man with his finger on the nuclear button?

Long has Trump’s irregular attitude been a source of fascination. Oft described by supporters as “refreshing”, his tumultuous outbursts are now finding new judgement. “Narcissistic, juvenile and dangerous” are just a few words that come to mind.

All leaders must make difficult choices, but most are predictable. What seems to separate Trump from his contemporaries is a complete lack of control. In short, Trump does not act like an adult.

Naturally, questions have been asked. Is he mad? What is his plan? These are important questions. But so is this one: is it right to question a leader’s mental health publicly?

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The team of psychiatrists from Yale obviously think so. And I agree. There are pragmatic safety issues concerned. If Trump is suffering from an undiagnosed mental illness, as unfortunate as it may be, he may not be fit for office. The rationality required to make complex decisions may be simply beyond his grasp. The main crux of the argument can be broken down to three questions:

Is it fair to question a leader’s health?

Can you make a diagnosis on speculation?

What are the next steps?

Within medicine, there are certain rules. One is to respect a patient’s autonomy and confidentiality. By these two mantras, one may argue that satellite diagnosis is always wrong. But equally, we must consider that a large number of mental health cases are brought to doctor’s attention by this very process. Often it is a concerned family member who raises the alarm. Or a member of the public. Or in the case of Donald Trump, millions.

From a societal perspective, it is completely fair to question someone’s ability based on their health. I will make it clear here that I am talking only in situations where the safety of the individual or those they serve are at risk. There is no judgement made of the character of the individual, only a functional assessment.

If I had a heart condition I may be offended at undergoing a medical for a desk job but could understand if I was asking to climb a mountain. Context is important.

When it comes to mental health, the waters are yet murkier. Can you be too depressed to be a doctor? Can you be too elated to be a comedian?

Both questions can be ultimately answered “Yes” when the extremes are considered. Severe depression slows your cognitive ability, and within the depths of my own, I would not consider myself safe. A comedian sparking public outrage for a joke is another example. Once again, context. But suggesting that a history of anxiety means you can’t be a teacher? Absurd.

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A public leader should be held to the same standards. If there is a significant concern, then that concern should be heard.

So: can you make a diagnosis on speculation? Believe it or not, medicine, like all science, is speculative. Certain tests may decrease clinical uncertainty, often to zero. But a patient presenting with chest pain may have one out of 100 problems.

Doctors ask questions, order tests and trial treatments based on the best evidence. A diagnosis may only become evident when a treatment begins to work. There are a whole range of conditions where the same treatment works, so a clear diagnosis may never be made. Such examples include a host of neurological and motor neurone diseases.

But it is crucial to point out that these diagnoses, or treatment plans, are made on good evidence. Speculation from afar is not good evidence. It is at best well-meaning concern or badly meant conjecture.

Psychiatric disease may be hard to spot; often creative comedians showing signs of mania are missed for years, because their symptoms don’t appear abnormal in context. If your accountant ran around the office joking and jumping, you may begin to ask questions. Equally, if your favourite comedian began to do your taxes, you may begin to ask more.

Speculation is only useful when teamed with an investigation. Satellite diagnosis is a poor diagnosis. So: what are the next steps?

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In medicine, if you feel unwell, you see a doctor. If you are concerned that a family member is unwell, you ask them to see a doctor. If they will not see a doctor, you may make them. Or if you feel they are in danger, you may seek professional help.

This happens regularly. When dad collapses with chest pain, you call an ambulance. You don’t think about his decision-making – you act in what you perceive as his best interests. The same could be said of a suicidal friend.

Now imagine that dad has had a heart attack. He has been warned not to undertake strenuous activity. He then decides to go back to work, as a pilot of a large commercial airline. You see him leaving for work, a grimace of pain on his face. Now, what is your responsibility? Another heart attack may not just mean losing dad, but hundreds of lives. It would not be unreasonable to talk him out of it – or, failing that, to pick up the phone.

In the case of public leaders, the approach should be the same. If there is significant concern that a leader’s health poses a real risk to themselves or others, it is the responsibility of the public to point this out. With Trump, the Yale team has done just that.

Perhaps it is time to listen.

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I do not agree that speculative diagnosis is correct or fair. I also believe that there are those who would wrongly use health status to discriminate. But I also believe that actual disease doesn’t give a damn about ethical debate. Cancer killed my grandfather, and he was a nice guy.

In the end, it comes down to whether someone is fit to do a job and whether it is safe for them to do so. For Trump, the stakes are high. I do not believe he should be diagnosed from afar, but I do believe that well-meaning concern should be met with investigation. Then again, that’s just me.