Seeking the Roots of Autism and Antisocial Personality in the Brain

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Experts have long noted that both autism and antisocial personality disorder are marked by problems with empathy, yet the differences between the two conditions couldn’t be starker.

Autistic people are anxious and misread social cues, but they typically care about not hurting others; they are also often incapable of manipulation. Those with antisocial personality disorder, however, are masters of bending people to their will and tend to have little fear. They actually enjoy causing people pain.

In recent research, scientists highlighted the brain differences associated with autistic and antisocial traits, finding clear distinctions that remain stable during children’s development. Researchers imaged 323 typically developing youth, starting at an average age of 11. They children were also rated by their parents on levels of autistic and antisocial traits: for example, autistic traits might include “has difficulty relating to peers” or “would rather be alone than with others,” and parents would be asked to designate how well these phrases fit their child. Antisocial traits included things like “lies easily and skillfully” and “acts without thinking of the consequences.”

None of the participants met the full criteria for either autism or antisocial personality disorder (in children, the latter is known as conduct disorder), and while diagnoses occur only when an individual embodies many characteristic traits, people with fewer or milder versions of the traits can be found throughout the population. Those who have what are known as subclinical traits (in autism spectrum conditions, this is also known as the “broader phenotype”) tend also to have less exaggerated versions of the brain differences seen in those who do have the diagnosis.

Although there was some correlation between the two types of traits — meaning that a person who had some autistic traits was also more likely to have some antisocial traits — that probably reflects the fact that both conditions can produce behavior that doesn’t conform to social norms, rather than genuine similarities in the underlying causes.

Indeed, the authors write: “Notably, the [brain] regions associated with autistic and antisocial traits were largely anatomically distinct,” calling them “strikingly different.”

Children with high autistic traits showed thinning (less brain tissue) mainly in the superior temporal and temperoparietal cortex, a region previously found to be smaller in autistic people. The area is associated with the processing of socially relevant information, particularly the ability to understand the minds of others and take different perspectives.

In the children with high levels of antisocial traits, however, thinning was seen in the anterior prefrontal cortex, a region previously shown to be diminished in adult psychopaths. The area is associated with moral reasoning, which is obviously impaired in those who enjoy manipulating and harming others.

Although the current research found that the differences in these areas were stable as the children grew up, fortunately, it is known that many children who are diagnosed with these conditions overcome related disabilities and some even “outgrow” the diagnosis entirely. For example, one recent study found that 10% of low-functioning autistic children “bloom” by adolescence and become high-functioning, and many high-functioning youth also improve significantly, some enough to lose the diagnosis entirely.

With conduct disorder, about 60% of children diagnosed with the condition develop antisocial personality disorder as adults, but far fewer wind up on the extreme end of the antisocial personality disorder spectrum, known as psychopathy or sociopathy.

The new study was published in the Journal of Neuroscience and conducted by researchers at the National Institute of Mental Health.

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