By Jordan SmollerJanuary 17, 2014


The Psychopath Inside: A Neuroscientist's Personal Journey into the Dark Side of the Brain by James Fallon

I HAVE A CONFESSION: I carry a genetic marker that studies have found to be the strongest known predictor of violent crime. It’s found in more than 90 percent of prison inmates in the US. It’s associated with antisocial personality disorder and psychopathic traits. In fact, those who carry the marker are about seven times more likely to commit murder compared to non-carriers. Brain imaging studies have documented a number of differences between carriers and non-carriers, including less gray matter in the orbitofrontal cortex, which in turn is also associated with antisocial personality and psychopathy. Should I be worried? Should I warn my friends and family? What is this powerful genetic predictor? It’s called the Y chromosome. 

If most psychopaths have a Y chromosome (that is, they are men), and I have a Y chromosome, then I’m likely to be a psychopath inside. If I told you this, you would easily see the error of my logic. But, surprisingly, the neuroscientist James Fallon bases his new book on just this kind of premise. 

Fallon has been the subject of a good deal of media attention since his story was featured in a 2009 Wall Street Journal article. He is a neuroscientist whose work has included research on brain imaging, stem cells, and neurochemistry. In 2005, a colleague asked him to look at brain scans from a series of about 50 murderers and see whether he could find any distinctive patterns. Fallon asked to have the killers’ scans mixed with others taken of healthy people and psychiatric patients and have the group labels removed so that he could review them blindly. Based on findings from previous research and his own experience as a neuroscientist, he identified abnormalities in several brain regions that distinguished the killers. Around the same time, he was conducting brain imaging and genetic research on Alzheimer’s disease and decided to include himself, his children, and other family members as healthy comparison subjects (perhaps tellingly, this is not something a research ethics board would typically approve). When he reviewed the scans, he claims that one had the unmistakable signature of a killer. It turned out to be Fallon’s own scan. He initially shrugged it off, but that episode set off a saga of self-examination that led Fallon to get in touch with his inner psychopath. 

The concept of psychopathy, like most psychiatric labels, has undergone several transformations since it was first described in the early 19th century. Philippe Pinel, a founding father of modern psychiatry, is credited with one of the earliest descriptions of psychopathy as a disorder. Pinel is remembered for his humane approach to mental patients, arguing for the “moral” treatment of the insane at a time when asylums were little more than dank and brutal warehouses for “lunatics.” He also produced one of the first modern classifications of mental illness around the turn of the 19th century, and in 1801 introduced a diagnosis of “manie sans délire” (mania without delirium) to describe patients who were rational and not psychotic but prone to impulsive violence and self-destructive behavior. 

Over the next 150 years, a succession of names were applied to describe the problems of patients who seemed to know right from wrong but who could be manipulative, violent, cruel, and criminal without a sense of remorse or empathy: “moral insanity,” “psychopathic inferiority,” “sociopathic personality.” What physicians called them and how they described these patients depended for the most part on which side they took in an ongoing debate: Are psychopaths born or made? Are they morally depraved or genetically defective? By the 20th century, though, leading clinicians had largely reached consensus on one point: these were people who were beyond treatment or rehabilitation. 

In 1941, the psychiatrist Hervey Cleckley ushered in the modern view of psychopathy and introduced the term to popular culture with his book, The Mask of Sanity. Cleckley, who lamented that the psychopath was “the forgotten man of psychiatry,” derived a clinical profile of the psychopath from detailed case studies. As the book’s title indicated, psychopaths appeared to be sane, intelligent, and charming, but behind this mask was a caldron of insincerity, remorselessness, pathologic egocentricity, and an impoverished emotional life. The psychopath was prone to antisocial behavior, but had a lack of anxiety, and was unable to form meaningful social connections. Cleckley was later a psychiatric expert for the prosecution of Ted Bundy, an exemplar of the psychopathic serial killer. 

Today, psychopathy is one of the most familiar psychiatric conditions — a staple of the criminal justice system and TV crime dramas. So it may come as a surprise that it doesn’t appear as a disorder in the DSM, psychiatry’s diagnostic manual. Instead, the DSM offers antisocial personality disorder (ASPD), a close cousin that involves a persistent pattern of criminal behavior, dishonesty, impulsivity, aggression, and a lack of remorse, Robert Hare, a psychologist who has become the most influential researcher on psychopathy, suggests that the split between the ASPD camp and the psychopathy camp emerged at a 1975 conference sponsored by NATO (yes, that NATO). Researchers who were influential in developing the modern DSM argued that the diagnosis should be based mainly on observable patterns of behavior rather than psychological constructs. And so, ASPD emphasizes aggressive behavior, rule-breaking, and criminal acts. Not surprisingly, 80–90 percent of inmates in maximum security prisons meet criteria for ASPD, though only 15–20 percent qualify as psychopaths. 

In recent years, the dominance of biological psychiatry and neuroscience has brought psychopathy under the lens of fancy brain scanning technologies and into the genetics lab. That’s the context in which Fallon encountered his own “psychopathic” brain. After reviewing his brain scan, he began to investigate further. He tells the story of attending a family barbecue where he learned that his family tree had some evil branches. From patricidal English monarchs in the 12th century to distant cousin Lizzie Borden, his father’s side of the family had more than its share of murderers. Looking back on his life, he now saw signs of his own bad-boy tendencies. Much of the book is a recounting of his dubious behavior. And he’s not afraid to paint a rather unflattering self-portrait to make the case, even when it comes to his own family. He recounts that after his wife was diagnosed with lymphoma, he hurt her deeply by flirting with other women. As he writes about his lack of empathy towards his wife, the reader can’t help but feel some sympathy for her:

I’ve never truly felt fully emotionally connected to Diane. My connection with her emerged partially because I didn’t connect empathically. I never understood her. She was fascinating to me, and still is. We have common goals and values — family, Libertarianism, agnosticism — so there’s a like-mindedness, but she always felt like someone from outer space. Fortunately, that has always been more than enough for me. 

He also acknowledges an emotional distance from his children: “I love my kids as friends. I have a lot of respect for them, but I almost forget they’re my kids.” 

Most of the behavior he describes is certainly unappealing, but is it psychopathic? He is a sore loser at Scrabble, blows off presentations to go meet girls at a bar, and doesn’t RSVP to party invitations in case something more exciting comes up. He enjoys manipulating others and has been known to lie to people to gain their trust. He absentmindedly leaves his young grandson at home alone to attend a family dinner. But, he’s careful to say, he has never been violent or intentionally harmed anyone, and his forays into rule-breaking are not exactly badass:

When I see a sign directing me to park somewhere proper and legal, whether for a restaurant or sports event, I will continue to ignore the rules, knowing that the sign is there to serve whoever put up the sign, and not the rest of us. I’ll find a place on the grass or next to a real space close to the door, partly because I’m lazy and partly because I like getting away with it. While these scofflaw behaviors are not really psychopathic in any serious sense, they do signify that I can be a real jerk, or as less polite people might call me, an asshole.

As Fallon’s litany of self-disclosure goes on, the reader is apt to feel like Fallon’s psychiatrist friend who, after hearing Fallon recite his putatively psychopathic traits, “just waved his hand to my face and said, ‘That’s okay, Jim, you needn’t tell me any more.’” 

Fallon’s story is further complicated because his self-diagnosis is not limited to being a “borderline psychopath.” He also reports that he developed obsessive-compulsive disorder as a teen, suffered recurrent panic attacks, and, after discussing his past with psychiatric friends and colleagues, decides that he also suffers from a type of bipolar disorder (which could explain the grandiosity and self-indulgence that he elsewhere attributes to psychopathy). 

In the course of telling his story, Fallon does make the important point that psychiatric disorders are not discrete categories. There is no bright line between normal and abnormal, between mental health and mental disorder. Robert Hare’s Psychopathy Checklist (PCL-R), the most frequently used scale to measure psychopathic traits, treats psychopathy as a dimension with scores ranging from 0 to 40 (although a cut-off of 30 is often used to classify clinically significant psychopathy). In studies of the wider population, about 2 percent score in the “possible psychopathy” range on a screening version of the PCL, and up to 30 percent endorse at least one or two items. The line that marks disorder is ultimately a normative judgment call. In the DSM, the line is typically drawn at the point that symptoms cause significant distress or impairment. But underneath it all, most of psychopathology is dimensional, not categorical. 

Ironically, the real problem with Fallon’s account is that he tends to overplay the science. In concluding that he has a psychopath’s brain, Fallon seems to have fallen prey to the “ecological fallacy” — the mistaken idea that group averages apply to an individual case. Research showing a connection between brain patterns and psychopathy are based on comparing groups of psychopaths to healthy controls. Studies have indeed found that, on average, psychopaths show statistical differences in the structure and function of circuits involving the prefrontal cortex and amygdala (as well as the striatum). But that doesn’t mean those patterns can be used to classify an individual: the distributions of the two groups overlap. And, like the Y chromosome, brain variations that may be correlated with psychopathy are not necessarily biological causes. So far, there are no known features of brain scans that are diagnostic of psychopathy. 

When he turns to genetics, the situation gets even more dicey. Fallon has his DNA genotyped for a few genes that have been associated with antisocial behavior or reactivity to stress in some studies. A variation in one of these, MAO-A, has even been dubbed “the warrior gene.” But the studies linking this gene to antisocial behavior suggest that carriers only show this link if they also have a history of childhood maltreatment — which he clearly says he does not. The other genes he discusses have shown no convincing association with ASPD or psychopathy. And even if they did, they wouldn’t add up to much. It’s increasingly clear that the genetic component of psychiatric traits and disorders involves thousands of genetic variations, each of which may have a tiny individual effect. There are no genes that that are known to predict psychopathic traits with any diagnostic validity. 

In other places, Fallon offers scientific hypotheses that have little or no basis in data. He speculates that “in areas with chronic violence, from Gaza to East L.A., the concentration of genes associated with psychopathy might be increasing as women mate with bad boys for protection and aggressive genes spread, increasing the violence and repeating the loop.” At another point, he claims that the MAO-A gene (located on the X chromosome) explains in part why there are more aggressive males in the population than females. He also suggests that Libertarians have a high-functioning prefrontal cortex and low-functioning amygdala and that psychopaths may be immune to most diseases because their resistance to stress bolsters their immune systems.

In the end, Fallon acknowledges that his behavior (let alone his brain and genes) doesn't really add up to a picture of psychopathy. He claims that he has many features of a psychopath except for being antisocial, and suggests that his upbringing in a supportive family spared him from becoming a full-blown case. He prefers to think of himself as a “pro-social psychopath”: “I tend to use my powers of charm, manipulation, and hedonism for good, or at least not bad.” 

Of course, like many us, Fallon does have one biomarker that is clearly associated with psychopathy: a Y chromosome. 


Dr. Jordan Smoller is associate vice chair of the MGH Department of Psychiatry and professor of psychiatry at Harvard Medical School. He is the author of The Other Side of Normal (William Morrow/HarperCollins, 2012).

LARB Contributor

Dr. Jordan Smoller is associate vice chair of the MGH Department of Psychiatry and director of psychiatric genetics. He is professor of psychiatry at Harvard Medical School and professor in the Department of Epidemiology at the Harvard School of Public Health in Boston. He is director of the Psychiatric and Neurodevelopmental Genetics Unit (PNGU) in the MGH Center for Human Genetics Research. Dr. Smoller also serves as co-director of the Genetics and Genomics Unit of the MGH Clinical Research Program. At Harvard Medical School, he is director of the Translational Genetics and Bioinformatics Program of the Harvard Catalyst. He is also science director of the Science of Health and Development Initiative at the Center on the Developing Child at Harvard University. Dr. Smoller is an associate member of the Broad Institute and a senior scientist at the Broad’s Stanley Center for Psychiatric Research. He is the author of The Other Side of Normal (William Morrow/HarperCollins, 2012).


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