Often, science gallops ahead of politics.

We've seen it with climate change when throughout the 1990s, researchers were warning about the consequences of rising greenhouse gas emissions.

Political action didn't occur in any serious way in North America until Barack Obama's second term as president.

The same is true with neuroscience, particularly with regard to psychopathy.

According to a 2007 Scientific American article, "it comprises at least three overlapping, but separable, constellations of traits: interpersonal deficits (such as grandiosity, arrogance and deceitfulness), affective deficits (lack of guilt and empathy, for instance), and impulsive and criminal behaviors (including sexual promiscuity and stealing)."

One of the leading researchers, UBC professor emeritus Robert Hare, was the subject of many articles in the 1990s after publication of his bestselling book, Without Conscience: The Disturbing World of the Psychopaths Among Us.

In 2006, Hare coauthored another book with Paul Babiak called Snakes in Suits: When Psychopaths Go to Work. They have often made the point that psychopaths are not always violent and many thrive in the higher echelons of corporations, where they wreak chaos.

The political world can also be turned upside down if a callous, manipulative, charming but emotionally cold psychopath rises to a high position, such as president, prime minister, premier, or governor.

Brain research provides insights into psychopathy

Advances in neuroscience have shed more light on psychopaths. This has been demonstrated in many papers published in peer-reviewed journals.

One such example last year appeared in the Journal of Personality.

University College London researchers Ana Seara-Cordoso and Essi Viding pointed out that functional magnetic resonance imaging is noninvasive. And it provides "excellent spatial and fairly good temporal resolution" in showing how blood flows and blood oxygenation in the brain respond to neural activity.

Here are their central conclusions from the abstract:

Extant data suggest that individuals with high levels of psychopathic traits show lower activity in affect-processing brain areas to emotional/salient stimuli, and that attenuated activity may be dependent on the precise content of the task. They also seem to show higher activity in regions typically associated with reward processing and cognitive control in tasks involving moral processing, decision making, and reward. Furthermore, affective-interpersonal and lifestyle-antisocial facets of psychopathy appear to be associated with different patterns of atypical neural activity. Neuroimaging findings from community samples typically mirror those observed in clinical samples, and largely support the notion that psychopathy is a dimensional construct.

A simple way of saying this is that functional MRI tests show that the brains of psychopaths light up in different ways than nonpsychopaths when asked to do certain tasks.

One of those tasks could be looking at emotionally loaded imagery or words. Psychopaths will not respond any differently than they would to more neutral pictures or text.

Scientists tend to be a cautious group of people and this paper mentioned "limitations" that needed to be addressed in future studies.

"First, different laboratories used different stimuli and paradigms with variable control conditions," Seara-Cordoso and Vining wrote. "This prevents a comprehensive and systematic evaluation of the contradictory findings. Second, there is still substantial work to be done to gain a fine-grained picture of the precise cognitive-affective deficit associated with psychopathy."

Psychopaths give themselves away through language

A 2012 Federal Bureau of Investigation journal highlighted relatively recent research into the speech patterns of psychopaths. The lead author was UBC associate psychology professor Michael Woodworth.

The article noted that psychopathic murderers "make fewer references to social needs relating to family and friends".

"Research indicated that the selfish, instrumental, goal-driven nature of psychopaths and their inability to focus on emotional aspects of an event is discernible by closely examining their language," the researchers wrote. "Psychopaths’ language is less emotionally intense. They use more past-tense verbs in their narrative, suggesting a greater psychological and emotional detachment from the incident."

Intriguingly, the paper mentioned that computerized language-analysis tools have been used to help researchers.

"The results indicated that when describing their murders, psychopaths more likely would provide information about basic needs, such as food, drink, and money," the researchers wrote.

Another paper in the same FBI journal noted that functional magnetic resonance imaging "indicates psychopaths are incapable of experiencing basic human emotions and feelings of guilt, remorse, or empathy".

"They display emotions only to manipulate individuals around them," wrote Babiak and FBI behavioural analyst Mary Ellen O'Toole. "They mimic other people's emotional responses."

They added: "The impulsive and irresponsible psychopath lives in a parasitic and predatory lifestyle, seeking out and using other people, perhaps, for money, food, shelter, sex, power, and influence."

Should political parties screen for psychopathy?

Anyone who read Ron Rosenbaum's outstanding book on Adolf Hitler, Explaining Hitler: The Search for the Origins of His Evil, could easily conclude that this political monster was very likely a psychopath. Rosenbaum explained how Hitler acted with stealth, deceit, and a great deal of charisma, even trying to distance himself from the massacre of millions of Jews, Gypsies, gays, and lesbians in Nazi concentration camps.

That's what's known as duping delight, which is something psychopaths often engage in.

So here's a question facing political parties around the world: should they screen potential leaders for psychopathy before they're nominated?

Should lawmakers familiar with psychopathy push for legislation requiring psychopathy screening for anyone who might want to become leader of a major political party?

The science makes it possible to conduct this type of testing. But will the public have to wait 20 years and after considerable havoc is created by yet another psychopathic world leader before something is done to alleviate the risk?

The Conservative Party of Canada is in the midst of a leadership campaign. The New Democratic Party of Canada is also about to launch a leadership race.

Perhaps most importantly, the U.S. Republican and Democratic parties are poised to nominate their presidential candidates.

Would Donald Trump and Hillary Clinton be willing to be screened for psychopathy to assure their critics that they're not manipulative, predatory, cold-blooded reptilian politicians purely guided by self-interest? Would their running mates also be willing to do this?

It's a question that influential American broadcasters Anderson Cooper, Christiane Amanpour, Megyn Kelly, or George Stephanopoulos might want to raise before U.S. voters go to the polls in November.