The Psycho Gene Strong Emotional Impulses

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the MAOA‑L group was less able to inhibit The psycho gene strong emotional impulses. But some trigger is still needed to tip MAOA‑L people towards violence. An ear- While the idea of a ‘criminal gene’ is nonsense, there is growing evidence lier study suggested that this trigger could that some psychopathic behaviour might indeed be grounded in genes be persistent maltreatment during childhood (Caspi et al, 2002). At first sight, Philip Hunter this suggests that nearly half the human population are predisposed to violence given these triggers, but the situation is not he notion that genes play an important gene MAOA encodes monoamine oxidase quite that bad—it is merely nearly half of role in many diseases has been widely A, an enzyme that degrades amine neuro men. Women are protected in two ways: Taccepted, but many find it much transmitters, such as dopamine, noradrenalin the MAOA gene is linked to the X chromo harder to acknowledge a similar link with and serotonin. A rare genetic disorder caused some so that women with the MAOA‑L particular behaviour or even predisposition by an MAOA mutation leads to MAOA defi- variety on one chromosome usually have to crime. Partly for this reason, the study of ciency and in turn an excess of monoamine a normal allele on the other; and there is behavioural genetics remains a controversial transmitters, causing excessive impulsive circumstantial evidence that women are topic, with disagreement not just over the behaviour including hypersexuality, sleep also protected by other genes from being science itself, but even more so about the disorder and extreme mood swings as well disposed to violence. therapeutic, societal and legal implications. as a tendency to violence, which is known as In any case, caution is needed to inter- Too much might have been made too Brunner syndrome. pret the findings of Mayer-Lindenberg’s soon of early findings that made corre group about the MAOA‑L allele, accord- lations between alleles of certain genes and … the study of behavioural ing to Ahmad Hariri, Investigator at the tendencies to antisocial or criminal behav- Institute for Genome Sciences & Policy iour. Indeed, most researchers in the field genetics remains a controversial at Duke University (Durham, NC, USA). were appalled by the decision of an Italian topic, with disagreement not just “This is a significant basic science find- appeal court in 2009 to cut the sentence of over the science itself, but even ing linking genes to brain to behaviour,” a convicted murderer by one year on the more so about the therapeutic, he said. “But it is not a significant clinical grounds that he had a version of the MAOA societal and legal implications finding in and of itself. Only in as much gene, which has been linked to aggression as this very, very, very subtle bias in the and violence (Feresin, 2009). There is equal brain tips the balance toward an aggres- dismay over some US courts that went the But while Brunner’s syndrome is rare, sive response to provocation is this finding other way and accepted genetic factors as having only been identified in five males even remotely clinically relevant.” In fact, evidence for the prosecution, leading to of one extended family, the MAOA‑L vari- as Meyer-Lindenberg himself has com- higher sentences on the basis that people ant is extremely common and occurs in mented, the MAOA-L allele is just one of with particular alleles cannot be cured and about 40% of the population. Clearly, most several genes—most of which are still not will remain a risk to society for longer. of these people are peaceable and have identified—that increase risk of violent or “Taking genetic factors into account never committed a crime, and yet a study antisocial behaviour. when sentencing is plain stupid, unless we involving researchers from Austria, Italy are talking about something like Down’s and the USA—headed by Andreas Meyer- ut the whole story takes a rather dif- syndrome or some other syndrome that Lindenberg, Director of the Central Institute ferent turn in the case of psycho drastically reduces intelligence and execu- of Mental Health in Mannheim, Germany— Bpathy, which is now widely regarded tive functioning,” insisted Anthony Walsh has discovered that at least males with this as a congenital state characterized by lack from the Criminal Justice Department at variant had neurobiological structural fac- of empathy or moral compass and defined Boise State University in Idaho, USA. “This tors that would predispose them to violence at least partly by genes, in contrast to other is the kind of “genetic determinism” that (Meyer et al, 2006). forms of sociopathy or antisocial personality liberals have worried themselves silly over. Using structural MRI scanning, the study disorder (APD), in which environmental fac- They just have to take one or two neuro- identified that people with MAOA‑L were tors make a major contribution (Fontaine & science and genetic classes to dispense more likely to have a smaller limbic sys- Viding, 2008). with their ‘my genes/neurons’ made me do tem—the hippocampus, amygdala, anterior “Psychopathy does seem to be heritable, it. Nothing relieves one of the obligation to thalamic nuclei and limbic cortex—which and appears to have its basis at least in part behave civilized.” participates in emotion, behaviour and in “biological” factors linked to basic emo- long-term memory. The team then applied tional systems, so that the mature psycho onetheless, the case against spe- functional MRI, which measures changes path never develops a complete set of cific alleles has been accumulating, in blood flow, and discovered that the notably for the low-expression vari- MAOA‑L group also showed hyperrespon- N “Taking genetic factors into ant of MAOA, known as MAOA‑L, which has siveness of the amygdala during tasks such been linked in various studies with increased as copying facial expressions. The amygdala account when sentencing is plain risk of violent and aggressive behaviour. The is associated with emotional processing and stupid…”

“…it is useful to think of charm, lack of empathy and guilt, proneness psychopathy as mainly the to boredom and sexual promiscuity. product of genes and sociopathy Although it is not part of the Hare checklist, psychopaths can also be detected by as more subject to environmental their lack of a “startle reflex”, which means influences” failure of their nervous system to respond to images or events that frighten or shock other pro-social emotions like empathy, guilt, and about 0.6% of the population, according to people, such as pictures of a decapitated the ability to truly care about and for others,” a recent study conducted in the UK (Coid corpse. These tests work just as well for psy- said Richard Wiebe, who specializes in the et al, 2009). Obviously, psychopathy does chopaths who have never indulged in vio- link between psychology and criminology not always lead to crime or extreme violence and apparently lead normal lives. They at Fitchburg State College in Fitchburg, MA, lent behaviour; indeed its occurrence in the can also be used to identify psychopathy in USA. Wiebe added though that the herit- population used to be significantly under- children, who exhibit the same symptoms, ability of underlying genetic factors had yet estimated because it was diagnosed only in particular pathological lying, lack of to be conclusively established. “In other in people who had already shown extreme empathy, tendency to violence, and lack of words, we know that the dependent varia- behaviour when many psychopaths do not. startle reflex—in fact, several studies have ble, that is psychopathy, is heritable, but not As there is no genetic or clinical test as found evidence of inherited psychopathy in enough about its causes to say that they are yet, psychopathy is still diagnosed in terms of quite young children (Viding et al, 2005). heritable. Nevertheless it is useful to think of behaviour, but taking account of various fac- psychopathy as mainly the product of genes tors in combination. Robert Hare, who led t also appears that psychopathy is more and sociopathy as more subject to environ- the UK study and is now at the Department common in men than women. This sup- mental influences.” of Psychology of the University of British Iports the theory that psychopathy might Environmental factors do play a part in Columbia in Vancouver, Canada, has be an adaptive personality trait that gives the behaviour of psychopaths, but in a differ- designed a test known as the ‘Psychopathy men a reproductive advantage through ent way than in other people who develop Checklist—Revised’ of about 20 symptoms greater tendency and ability to form numer- antisocial tendencies. The condition is more that he uses to diagnose psychopathy. These ous relationships and so have more chil- common than was once thought and affects include pathological lying, superficial dren. This is unproven, but it is certainly true

that male psychopaths tend to form large … irrespective of where future way morally wrong, according to Jones. But numbers of short-term relationships and can research leads, genes should not they are more likely to respond to reward. have an almost seductive charm. “One example of this is currently underway However, the trait would lose its advan- influence sentencing decisions at a school in Buckinghamshire (UK) for tage if it became too common in the popu- one way or the other because they primary aged children with Emotional and lation. A particular trait tends only to be can never be deemed responsible Behavioural Difficulties,” said Jones. “There advantageous in certain environmental for behaviour have been very encouraging reports from conditions as was pointed out in the context teachers so far. The intervention is largely of psychopathy by Essi Viding, Co-Director reward based, and the pupils gain rewards of the Developmental Risk and Resilience psychopathy and antisocial behaviour at by working toward reaching their behav- Unit at the Department of Psychology at Goldsmiths College, University of London, ioural targets each week. Pupils can ‘cash- University College London, UK. “I think that UK, suggests that the condition could be in’ their rewards daily, or they can save them the simple game of evolution is to ensure much more common among women than up for a more substantial reward later in the survival of the species under different envi- studies suggest . It might be that women will, week.” ronmental conditions,” she said. “In some in many cases, fail to register on the Hare Whether this will help these children conditions it may be adaptive to be anxious Psychopathy Checklist—Revised because to lead constructive adult lives remains to and cooperative, in other conditions it may the more extreme traits are cushioned by be seen. It does provide further evidence be good to exploit and be antisocial. This of other female factors. “There is some evi- though that while it might not be possible course is effectively contrasting alleles that dence to support this idea,” said Jones, cit- to cure psychopaths, it may be possible to have very different effects. Hence, the same ing work by Randy Salekin at the University direct their selfish tendencies away from allele may serve an individual very well (and of Alabama, in the USA (Salekin et al, 1997) crime and violence towards more positive in a socially acceptable manner) in one situ- who found that just as many women as men and creative activities. ation, but not in another.” pass the Hare test in terms of their lack of empathy, but not on the more violent and REFERENCES Caspi A, McClay J, Moffitt TE, Mill J, Martin J, …psychopathy might be an impulsive criteria. “So, while the inter Craig IW, Taylor A, Poulton R (2002) Role of adaptive personality trait personal aspects of psychopathy seem to be genotype in the cycle of violence in maltreated present and similar in males and females, children. Science 297: 851–854 that gives men a reproductive the behavioural aspects of psychopathy are Coid J, Yang M, Ullrich S, Roberts A, Hare RD advantage through greater (2009) Prevalence and correlates of psychopathic very much male-heavy,” said Jones. traits in the household population of Great tendency and ability to form Britain. Int J Law Psychiatry 32: 65–73 numerous relationships and so his comes back to the question of Feresin E (2009) Lighter sentence for murderer with ‘bad genes’. Nature doi:10.1038/news.2009.1050 have more children treatment and sentencing. Viding argues that irrespective of where future Fontaine N, Viding E (2008) Genetics of T personality disorder. Psychiatry 7: 137–141 research leads, genes should not influence Meyer JH, Ginovart N, Boovariwala A, Sagrati S, This leads back to the observation that sentencing decisions one way or the other Hussey D, Garcia A, Young T, Praschak- psychopathy seems to be more common in because they can never be deemed respon- Rieder N, Wilson AA, Houle S (2006) Elevated men than women, which could have two sible for behaviour. “Any gene alone will monoamine oxidase A levels in the brain: an explanation for the monoamine imbalance of possible explanations. First, it might be true be neither necessary, nor sufficient to pre- major depression. Arch Gen Psychiatry 63: at the genetic and neurological level, in dispose someone to high levels of psycho 1209–1216 particular if some of the relevant genes are pathic traits and as such, the responsibility Salekin RT, Rogers R, Sewell W (1997) Construct linked to the X chromosome. Yet, this is spec- for choosing to offend still resides with an validity of psychopathy in female offender ulative as few genes have been identified that individual,” she said. “Most ‘risk genes’ are sample: a multitrait–multimethod evaluation. J Abnorm Psychol 106: 576–585 contribute specifically to psychopathy, with common in the population and yet do not Viding E, Blair RJR, Moffitt TE, Plomin R (2005) most of the evidence for its heritability being cause the majority of the individuals carry- Evidence for substantial genetic risk for statistical. There is the case of the X‑linked ing them to offend.” psychopathy in 7‑year‑olds. J Child Psychol MAOA gene, but that has only been associ- But the situation is different when it comes Psychiatry 46: 592–597 ated with general antisocial tendencies. to treatment—the appropriate therapy will Philip Hunter is a freelance journalist There is in any case an alternative expla- depend on underlying personality tenden- in London, UK. nation for the apparent gender difference cies. Psychopaths tend not to respond well in psychopathic prevalence. Alice Jones, to punishment because they cannot associ- EMBO reports (2010) 11, 667–669. specialist in childhood and adolescent ate it with acts they do not consider in any doi:10.1038/embor.2010.122