Antisocial behaviour ranging from lying, stealing and manipulating to physical violence, torture or killing is an aspect of mental health I am frequently asked about.
Of course, behaviours such as these can really range from mild to severe and cause varying levels of dysfunction or danger to both individuals and those they come in contact with.
Generally antisocial behaviours crop up in childhood or adolescence and can continue throughout life if they are not dealt with.
As with most things, there are both biological and environmental contributions to antisocial behaviours.
In severe cases, antisocial personality disorder could be involved, but this is not always the case. Some people simply behave badly but don’t have a specific psychiatric diagnosis.
In case you needed one more reason to quit smoking, maternal smoking during pregnancy has been implicated in some studies as a potential contributing factor for antisocial behaviour– and this connection remained even after controlling for other factors such as socioeconomic issues, education, marital state and antisocial behaviour in the mother.
Head injuries can also contribute to antisocial behaviour. In a study of 145 serial killers, approximately one quarter had experienced lengthy periods of unconsciousness from head injury during childhood or early adolescence.
Childhood abuse is the most common contributor to antisocial behaviour. Boys who have been abused are at risk for antisocial personality disorder and future violent offences. In the case of abuse, the earlier the abuse is experienced, the more likely the victim will develop problems with antisocial behaviour.
Serial killers often come from horrific backgrounds where they have been brutalized by one or both parents.
In the absence of abuse, good parenting and early life relationships likely have a protective effect. It isn’t surprising to learn that inconsistent discipline and lack of supervision during childhood has been associated with later development of maladaptive or antisocial behaviours.
Further, hanging out with the wrong crowd or witnessing violence firsthand or via the media can also contribute.
Children with no friends are also at higher risk for developing problems. A majority of serial killers are loners and unable to enter into normal relationships. In fact, the rate of schizoid personality disorder – characterized by a pervasive pattern of detachment from social relationships and emotions in interpersonal settings - is about 50 times higher among serial killers than in the general population.
Aside from these environmental influences, genetics can also play a role and it seems physical aggression is more often inherited than simple rule breaking behaviour.
So far a handful of genes have been implicated. Those identified are involved in the creation of various neurotransmitters and their receptors within the body.
One example is the gene for monoamine oxidase A (MAOA). In studies of mice, aggression increases when this gene is removed and it lessens when the gene is restored. Among humans, a study found five men in a single family who lacked this particular gene and all had engaged in antisocial behaviours including arson, exhibitionism and attempted rape.
Another study found two variants of this MAOA gene accounted for why some boys developed antisocial behaviour after childhood abuse while some did not.
Boys who had been abused and had a short version of this gene accounted for only 12 per cent of the study sample, but 44 per cent of the convictions for violent acts. Of those who had been severely abused and also had the short version of this gene, 85 per cent had engaged in some sort of antisocial behaviour.
Although genetic vulnerabilities exist, the best data to date still shows that much antisocial behaviour could be prevented. We need to ensure children are given the proper environment during their early years – free of abuse and neglect.