Wray Herbert has written about psychology and mental health for many years.

Early on in this timely, ambitious volume, neurobiologist and science writer Dean A. Haycock offers the reader a mental exercise. He presents two case histories, each a biographical sketch of an unidentified but well known public figure who came of age in very difficult circumstances. One was born into a nation at war, narrowly escaping enemy bombs, and later endured repeated beatings at the hands of his troubled father. He ran away from home for the final time at age 15. The other also grew up in a dysfunctional family, with a cruel, then absent, father. He and his mother lived in chronic poverty, continually on the move, and as a result he never had any real education.

After sketching out these early lives, Haycock reveals the identities. The first grew up to be David Clayton-Thomas, the highly successful frontman for the rock band Blood, Sweat and Tears. The other grew up to be Joseph Stalin.

Haycock’s goal in “Tyrannical Minds” is to sort out all of the influences that combine to produce a hateful, immoral despot, and his point here is that it takes a lot more than a terrible childhood to turn someone into a merciless tyrant. Some of the well-known despots Haycock profiles here — Stalin, Adolf Hitler, Mao Zedong, Kim Jong Un, Idi Amin, Moammar Gaddafi and Saddam Hussein — did experience personal dislocation early on, but others — such as Mao — were privileged and coddled. The rare emergence of a full-blown tyrant appears to require much more; an unusual combination of vaulting ambition, bad genes and dark personality, and the opportunity to exploit an ailing nation.

Does President Trump fit in this rogues’ gallery? That’s the underlying question in this historical analysis, and of these contributing factors, it’s personality that most interests Haycock, who draws heavily on others’ psychological profiles of history’s most vile characters. There is wide professional agreement about the traits that make up human personality, supported by an extensive scientific literature, and also about — most relevant here — the traits that add up to malignant personality. Scientists refer to this constellation of traits as the Dark Factor of Personality, or “D-factor,” and it’s worth spelling out these traits in a bit of detail here.

Perhaps most germane to an analysis of political tyranny is Machiavellianism, which describes the “consistent use of deception, lying, manipulation and exploitation of others in order to achieve a goal or maintain power.” Stalin demanded loyalty but had no loyalty to those who helped him gain power, eliminating anyone who was perceived as a threat. Closely related, and also common in the personality of tyrants, is moral disengagement. Despots convince themselves that the usual moral standards don’t apply to them, ignoring or excusing criminal behavior — even murder in the extreme — by any follower who is useful.

Malignant personality is often accompanied by an extraordinary sense of entitlement, Haycock said — the belief that one has the right to, and deserves, better treatment than others. The psychologically entitled crave admiration and praise, and often “demean, insult and begin vendettas against news organizations which ask hard questions or publish critical stories.”

Other dark traits include (to compress a bit) extreme self interest, callousness, emotional deficits, lack of empathy and pathological sadism — taking pleasure in the abuse of others. Finally, and arguably most central to this dark personality, is narcissism — “extreme self-absorption accompanied by an unrealistic, inflated image of oneself.” Serious features of pathological narcissism include harmful, petty and vindictive responses to any criticism or threat to the narcissist’s “over-inflated, fragile self-image.”

Despite Trump’s shadowy presence here, this was not meant to be a book about the president. Haycock says that, when he first outlined his project, he didn’t intend to include any American presidents in his analysis. But in the end, he devotes a third of the book to a history of homegrown tyranny, and to the current president in particular. Trump comes across as a poster boy for malignant personality, overshadowing all the other historical dictators, whose profiles seem skimpy by comparison.

But does this mean the president is mentally ill — as some psychiatrists have publicly argued — or unfit for office? Does this unfortunate constellation of traits — lust for power, sadism, narcissism and more — necessarily add up to a diagnosable mental disorder, such as psychosis or legal insanity? Haycock hedges his bets a bit more than many readers will like on this pressing, overarching question, deferring mostly to other psychological profilers and mental health specialists. He takes pains to distinguish between a narcissistic personality profile, on the one hand, and narcissistic personality disorder, a much more serious and threatening condition. There are many, mostly harmless, people who engage in “everyday narcissism,” he contends, but they rarely have a full-blown psychiatric disorder.

Similarly, most experts would not label Trump psychotic. Unlike someone with schizophrenia, for example, he does not hallucinate a separate reality, even if he does insist on an alternative set of facts. Nor is he legally insane. He knows right from wrong, even if he rejects many commonly held moral standards. What’s more, Trump does not appear distressed by any of his own dark traits. We may not like his maddening egotism and manipulative behavior, but such “Trumpism” does not appear in psychiatry’s diagnostic manual.

Haycock considers Trump’s professional success significant. He has benefited from his malignant traits again and again for a long time, and he has not “decompensated” under the extreme stress of the Oval Office. “Decompensation” is psychiatric jargon: The fact that he has not decompensated means he has not descended into madness. He is pretty much the same disagreeable person he has always been.

But as Haycock seems to conclude, that in itself does not mean he isn’t bad — or bad for the country. Moral impairment is not madness, nor is it certifiable mental illness. But it’s still impairment, and worrisome. The author concludes: “His narcissism guarantees that he will always look out for himself first and last. Donald Trump’s only loyalty is to Donald Trump. He is a successful man trapped in narcissism. Now, to a considerable degree, the nation is, too.”

Tyrannical Minds

Psychological Profiling, Narcissism, and Dictatorship

By Dean A. Haycock

Pegasus. 317 pp. $27.95