People who have a long history of antisocial behavior throughout their life may have a different brain structure to others, according to a new study.

Researchers from University College London have shown that people who persistently exhibit antisocial behavior – such as lying, violence, overaggression, and bullying – throughout their life are more likely to have a thinner cortex and smaller cortical surface area in certain regions of the brain than those who only behaved antisocially during their adolescence.

However, it remains unclear whether this is the product of “nature” or “nurture”. The researchers did not look into what extent these changes are inherited or related to environmental influences, such as childhood abuse, physical trauma, poor nutrition, or drug abuse.

"Our findings support the idea that, for the small proportion of individuals with life-course-persistent antisocial behavior, 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 behavior. These people could benefit from more support throughout their lives,” lead author Dr Christina Carlisi, Division of Psychology and Language Sciences at University College London said in a statement.

"Most people who exhibit antisocial behavior primarily do so only in adolescence, likely as a result of navigating socially difficult years, and these individuals do not display structural brain differences. It is also these individuals who are generally capable of reform and go on to become valuable members of society,” Dr Carlisi added.

Reported in the journal Lancet Psychiatry, researchers carried out MRI brain scans on more than 670 people aged 45 years old, 80 of whom had long-term antisocial behavior and 151 who had antisocial behavior only during their adolescent years. 

The team found that people with life-long antisocial behavior had reduced cortical surface area in 282 of 360 brain regions and a thinner cortex in 11 of 360 regions. The researchers note that many of these regions have previously been implicated in antisocial behavior through their involvement in goal-directed behavior, regulation of emotions, and motivation.

Independent scientists not directly involved with the research have praised this study as the “largest and most persuasive so far” of its kind. However, they also hastened to add that it leaves many questions unanswered about what exactly is causing these changes to the brain. 

“Most twin and adoption studies concur that heredity accounts for about half of variability between individuals in sociability, so that environmental influences such as childhood abuse or poor nutrition probably play equally important roles,” said Professor John Stein, a leading physiologist and trustee of the Institute for Food, Brain, and Behaviour, commenting on the new study.

“Because it is potentially reversible, the devastating effects of poor nutrition on the developing brain, particularly lack of the omega 3 long-chain fatty acid, docosahexaenoicacid (DHA), should be recognized in future studies.”