[Violent behavior in men due to genetic predisposition and childhood abuse: an hypothesis]

Caspi et al. recently reported that the likelihood of an abused child becoming violent as an adult hinges on a gene regulating the expression of monoamine oxidase A. This enzyme metabolises neurotransmitters. The scientists followed 442 boys from birth to their mid twenties and found an interaction between childhood abuse and a genetic polymorphism. Major strengths of the study are the longitudinal design and the excellent follow-up rate. Moreover, childhood abuse and antisocial behaviour are operationalised in various manners. The different forms of childhood abuse and neglect are, however, summarised and individual results are only presented for the different outcomes. In this way the consistency of the results is shown, but significance is only reached for one outcome: 'antisocial personality disorder symptoms'. It is especially important to replicate the study that investigated an association but no causal mechanism. Thus, conclusions about susceptibility to childhood abuse or medical treatment options for neglected children are premature.