Lower serotonin responsiveness in the brain during childhood predicts the development of antisocial personality disorder in early adulthood, according to a new study.

Low levels of serotonin, a neurotransmitter in the central nervous system, have been associated with several disorders, including increased aggression and depression.

It is known that impulsive aggression in adulthood is associated with disturbances in serotonergic function, but until now research examining this association in childhood has produced inconsistent results.

This prospective study, published in the May issue of the British Journal of Psychiatry, examined the relationship between serotonergic function measured in childhood and the later emergence of personality disorder.

Hormonal response to a serotonin-releasing agent was assessed in 58 children with attention-deficit hyperactivity disorder (ADHD) between 1990 and 1997, when they were aged between 7 and 11.

Approximately 9 years later, they were evaluated for antisocial personality disorder. 29% of the sample met the criteria for the condition and as a group had lower responses to the releasing agent during childhood, relative to the people who did not have antisocial personality disorder.

Boys who went on to develop antisocial personality disorder were also found to have more relatives with the diagnosis.

The researchers comment that these are remarkable findings, given that serotonergic responsivity was measured 9 years before the assessment of antisocial personality disorder, and was not at the time associated with severity of childhood aggression.

These results provide a critical link between research among children and adults on impulsive aggression and serotonergic function, because this is the only study that spans the developmental period between childhood and early adulthood.

The researchers comment that they do not suggest that disturbances in serotonergic function are the only feature leading to antisocial personality disorder, but are one aspect of a complex interplay between biological and psychosocial variables.