People have long been fascinated with the idea of psychopaths, wWatercolour head. Credit: Dr After 123ith violent ‘psychopathic’ characters turning up time and again in books, television and film. However, whilst people with psychopathic characteristics may have an increased risk of violence, this is far from a defining feature. Instead, psychopathy is characterised by an extreme lack of empathy. Psychopaths may also be manipulative, charming and exploitative, and behave in an impulsive and risky manner. They may lack conscience or guilt, and refuse to accept responsibility for their actions. Psychopathy is one of the most well-known and well-studied personality disorders. But is there an underlying biological reason for psychopathy? And if so, can the disorder be cured?

Research has suggested that the areas of the brain involved in emotion processing, empathising and decision making – for example amygdala, insula and ventromedial prefrontal cortex – show reduced activity in people with psychopathic characteristics when they see other people in distress or try to learn consequences of their actions. The impaired functioning of these areas of the brain affects the ability of individuals with psychopathy to form associations between stimuli and consequences, such as hurting other people and the fear and distress others display as a consequence, or making a poor choice and receiving a punishment. Altogether, the reduced activity within these areas of the brain impairs responses to emotional stimuli and decision making. The key question is: do these differences in the brain make someone into a psychopath, or does their behaviour change the brain?

Children that show a lack of empathy, lack of guilt and have shallow emotions, defined as callous-unemotional traits, are at increased risk of developing psychopathy in adulthood. These children are more likely to display anti-social behaviour, such as bullying and aggression. They are less likely to respond to socially rewarding stimuli such as happy faces, and are also less likely to recognise a fearful expression. Adolescents with callous-unemotional traits may be more likely to enjoy being cruel than being kind. They are also less likely to form long-term friendships, as they may not experience enjoyment from these relationships. Twin and adoption studies can be used to investigate whether these behaviours are influenced more by someone’s genes or their environment. Identical twins share all of their DNA, whereas fraternal twins only share half their DNA (like other siblings). If a characteristic is more likely to be shared by identical twins than fraternal twins, this suggests that genetic influences are important in explaining individual differences on that characteristic. Adoption studies are also useful as the child shares no DNA with their adoptive parents, but their adoptive parents provide all their environment. This enables researchers to study the causal impact of parental input on behaviour. Twin and adoption studies have suggested that callous-unemotional traits in childhood have a genetic basis, and that anti-social behaviour coupled with callous-unemotional traits is more influenced by genes than anti-social behaviour alone. However, adoption findings strongly indicate that the genetic vulnerability is not a destiny, but can be counteracted by protective environmental influences.

There are many implications of the research into callous-unemotional traits and psychopathy. As we seek to better understand how these features develop and how people with these features see the world around them, we can better tailor interventions to suit individual needs. It is clear that intervening early in children with callous-unemotional traits could prevent psychopathy in adulthood, with all the psychological and social consequences.

Professor Essi Viding is a leader in this area of research and is the winner of the Royal Society Rosalind Franklin Award and Lecture 2017. Join us on 19 October to hear Professor Viding discuss how psychopathy arises and how it might be prevented in her lecture ‘Why do some people become psychopaths?’.