Donald Trump may be a “world-class narcissist”, but he does not display signs of having narcissistic personality disorder, according to the psychiatrist who wrote the criteria that defines the disorder.

Professor Allen Frances, the psychiatrist who wrote the defining clinical characteristics for narcissistic personality disorder (NPD) said the President does not meet them, and warned against labelling Mr Trump as “mentally ill”.

In a letter to the New York Times, Professor Frances said that such psychiatric name-calling “is a stigmatising insult to the mentally ill (who are mostly well behaved and well meaning) to be lumped with Mr. Trump (who is neither)”.

“He may be a world-class narcissist, but this doesn’t make him mentally ill, because he does not suffer from the distress and impairment required to diagnose mental disorder,” he said.

According to Psychology Today, to which Professor Frances contributes, NPD is indicated by five or more of the following symptoms:

Exaggerates own importance

Is preoccupied with fantasies of success, power, beauty, intelligence or ideal romance

Believes he or she is special and can only be understood by other special people or institutions

Requires constant attention and admiration from others

Has unreasonable expectations of favourable treatment

Takes advantage of others to reach his or her own goals

Disregards the feelings of others, lacks empathy

Is often envious of others or believes other people are envious of him or her

Shows arrogant behaviours and attitudes

Psychology Today notes that 50-75 per cent of the people diagnosed with narcissistic personality disorder are male.

It also warns that it is common for many adolescents to display the characteristics listed above but says “this does not indicate that they will later develop narcissistic personality disorder”.

Professor Frances, who is currently professor emeritus of psychiatry and behavioural sciences at Duke University Medical College, finished his letter with a withering verdict on Mr Trump’s cognitive impetuses and indicated that challenging the President’s mental health would be unproductive.

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