Kids who lie, steal, bully well into adulthood may have smaller brain surface area: Lancet study

People who exhibit lifelong, persistent antisocial behaviour, may have smaller surface areas in several brain regions compared to those who do not exhibit the trait, according to a study which may lead to better interventions for juvenile offenders.

The study, published in the journal The Lancet Psychiatry, noted that individuals exhibiting life-course-persistent antisocial behaviour like stealing, lying, bullying, or violence may have thinner outer brain layer, the cortex, and smaller surface area in regions associated with antisocial behaviour, compared to those who do not exhibit the trait.

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According to the researchers, including those from the University College London (UCL) in the UK, some people display life-course-persistent antisocial behaviour that begins in childhood and lasts into adulthood, whereas others exhibit the trait in adolescence which desists as they mature into adults.

In the study, they compared structural brain differences using MRI scans in people with either life-course-persistent or adolescent-only antisocial behaviour, and those without the trait.They said the results provided the first robust evidence to suggest that underlying neurological differences are primarily associated with life-course-persistent antisocial behaviour.

"Our findings support the idea that, for the small proportion of individuals with life-course-persistent antisocial behaviour, there may be differences in their brain structure that make it difficult for them to develop social skills that prevent them from engaging in antisocial behaviour," said study lead author Christina Carlisi from UCL.Carlisi said these people could benefit from more support throughout their lives.

"Most people who exhibit antisocial behaviour primarily do so only in adolescence, likely as a result of navigating socially difficult years, and these individuals do not display structural brain differences," she added.

According to Carlisi, these individuals are generally capable of reform, and go on to become valuable members of society.In the study, the researchers used MRI brain scans from 672 participants aged about 45 years.

They assessed reports on conduct problems of the participants from parents, carers, and teachers, as well as self-reports between ages seven and 26 years.

Based on these reports, the scientists categorised the participants in terms of the patterns of behaviour they exhibited -- 12 per cent (80 people) had life-course-persistent antisocial behaviour, 23 per cent (151) had adolescent-only antisocial behaviour, and 66 per cent (441) had no history of persistent antisocial behaviour.

Using the brain scans of the participants, they also measured and compared the average thickness and surface area of the cortices between the three groups.The researchers also analysed differences in the surface area and cortical thickness of 360 different regions of the cortex, the study noted.

The findings revealed that, across the entire brain, individuals with life-course-persistent antisocial behaviour had, on average, a smaller surface area, and lower cortical thickness than people who showed no persistent antisocial behaviour.

People who showed life-course-persistent antisocial behaviour also had reduced surface area in 282 of 360 brain regions, and had thinner cortex in 11 of 360 regions, the scientists reported.Most of these regions, they said, are associated with antisocial behaviour through their involvement in goal-directed behaviour, regulation of emotions, and motivation.

According to the researchers, the findings provide the first robust evidence to suggest that neurological differences exist in people with life-course-persistent antisocial behaviour with implications for the way juvenile offenders are treated.

However, they cautioned that the study is only observational, and does not reveal if these brain characteristics are inherited, or resulting from experiences early in life.

"It is unclear whether these brain differences are inherited and precede antisocial behaviour, or whether they are the result of a lifetime of confounding risk factors (eg, substance abuse, low IQ, and mental health problems) and are therefore a consequence of a persistently antisocial lifestyle," said study co-author Essi Viding from UCL.