Using both an electroencephalograph (EEG), which measures electrical activity in the brain, and functional magnetic resonance imaging scans, which measure oxygen use, [Kent A. Kiehl] found striking differences between psychopaths and non-psychopaths in the activity of several regions of the brain. He is particularly intrigued by abnormalities in psychopaths' brains, in what he calls the paralimbic system, a loose organization of brain structures involved in processing emotion.
The precise nature of the affective deficit seen in psychopaths remains unclear. Some authors have emphasized deficiencies in the experience and expression of specific emotions such as fear (Lykken, 1957) and empathy (Blair, 1995). Other authors (e.g., Schalling, 1978) have proposed that psychopaths display a global affective deficit which would impair their experience and/or expression of a broad spectrum of emotions, both negative and positive, making them both desireless and fearless.
Is there a drug that would reduce the risk of psychopaths? There is not much research on drug treatment for psychopathy, but it is a sensible avenue for exploration. Psychopaths have a different physical make up; giving them a drug to make their neurophysiology more similar to ours might make them less dangerous.
Psychologists estimate that one in every 100 people is unfeeling enough to qualify as a psychopath, with an especially heavy concentration among criminals.
The ranks include serial killers such as Ted Bundy, who charmed and killed dozens of young women in the 1970s, and cannibal- murderer Jeffrey Dahmer, who fatally seduced 17 men and boys before he was caught in 1991, as well as a great many other people who never commit a crime punishable by law, but go through life heartlessly using and manipulating others without remorse.
A preliminary examination of the mean differences between psychopaths and nonpsychopaths with regard to childhood variables found significant differences for a number of childhood variables, with inconsistent discipline and supervision emerging particularly strongly (see Table 2). Both school variables were also significantly different, with psychopaths doing less well at school and perceiving school more negatively than nonpsychopaths.
Psychopaths, of course, are well-known for their resistance to punishment. Their lack of fear means they don’t worry about physical pain or harm, and their lack of concern for the feelings of others means social punishment doesn’t work either. If you don’t care if you hurt or disappoint people — and aren’t bothered by rejection — you won’t feel ashamed or guilty or embarrassed, and consequently won’t be motivated to avoid those feelings.
Virtually all psychopaths are men. She says they can be so likable that "they're able to make some of the female staff members fall in love with them." They are less affected by punishment than other people. Many of the most severe sex offenders, particularly rapists, are psychopaths. Psychopaths are the most treatment- resistant of all criminals, Rice's research shows.
A key-defining characteristic of psychopaths is that they have no conscience ( Hercz, 2001;  Stout, 2005b) and are incapable of experiencing the feelings of others. Their other characteristics however ( Walker, 2005) make them appear very hireable and worthy of promotion; they are smooth, adroit at manipulating conversations to subjects they want to talk about, willing to put others down, are accomplished liars, totally ruthless and opportunistic, calculating and without remorse.
One in 25 bosses may be psychopaths — a rate that’s four times greater than in the general population — according to research by psychologist and executive coach Paul Babiak.
Babiak studied 203 American corporate professionals who had been chosen by their companies to participate in a management training program. He evaluated their psychopathic traits using a version of the standard psychopathy checklist developed by Robert Hare, an expert in psychopathy at the University of British Columbia in Canada.
Research on psychopaths has "skyrocketed" in recent years, Hare says, particularly in the United States, Canada, Scandinavia and Germany.
Researchers examining brain activity have tended to find abnormal activity in the amygdala, a part of the brain seen as the seat of basic emotions like fear, and the orbito-frontal cortex, which is involved in helping people adjust their behaviour in response to reward or punishment.
Some studies also indicate problems in the connection between the deep, emotional brain and the thinking part of the brain.