by Jalees Rehman
Can neuroscience help identify individuals who are most prone to engage in violent criminal behavior? Will it help the legal system make decisions about sentencing, probation, parole or even court-mandated treatments? A panel of researchers lead by Dr. Russell Poldrack from Stanford University recently reviewed the current state of research and outlined the challenges that need to be addressed for "neuroprediction" to gain traction. The use of scientific knowledge to predict violent behavior is not new. Social factors such as poverty and unemployment increase the risk for engaging in violent behavior. Twin and family studies suggest that genetic factors also significantly contribute to antisocial and violent behavior but the precise genetic mechanisms remain unclear. A substantial amount of research has focused on genetic variants of the MAOA gene (monoamine oxidase A, an enzyme involved in the metabolism of neurotransmitters). Variants of MAOA have been linked to increased violent behavior but these variants are quite common – up to 40% of the US population may express this variant! As pointed out by John Horgan in Scientific American, it is impossible to derive meaningful predictions of individual behavior based on the presence of such common gene variants.
One fundamental problem of using social and genetic predictors of criminal violent behavior in the legal setting is the group-to-individual problem. Carrying a gene or having been exposed to poverty as a child may increase the group risk for future criminal behavior but it tells us little about an individual who is part of the group. Most people who grow up in poverty or carry the above-mentioned MAOA gene variant do not engage in criminal violent behavior. Since the legal system is concerned with an individual's guilt and his/her likelihood to commit future violent crimes, group characteristics are of little help. This is where brain imaging may represent an advancement because it can assess individual brains. Imaging individual brains might provide much better insights into a person's brain function and potential for violent crimes than more generic assessments of behavior or genetic risk factors.
Poldrack and colleagues cite a landmark study published in 2013 by Eyal Aharoni and colleagues in which 96 adult offenders underwent brain imaging with a mobile MRI scanner before being released from one of two New Mexico state correctional facilities. The prisoners were followed for up to four years after their release and the rate of being arrested again was monitored.


