From Genes to Brain to Antisocial Behavior

This review summarizes recent brain-imaging and molecular-genetic findings on antisocial, violent, and psychopathic behavior. A ‘‘genes to brain to antisocial behavior’’ model hypothesizes that specific genes result in structural and functional brain alterations that, in turn, predispose to antisocial behavior. For instance, a common polymorphism in the monoamine oxidase A (MAOA) gene has been associated with both antisocial behavior and also reductions in the volume of the amygdala and orbitofrontal (ventral prefrontal) cortex—brain structures that are found to be compromised in antisocial individuals. Here I highlight key brain regions implicated in antisocial behavior, with an emphasis on the prefrontal cortex, along with ways these areas give expression to risk factors for antisocial behavior. Environmental influences may alter gene expression to trigger the cascade of events that translate genes into antisocial behavior. Neuroethical considerations include how responsibility and punishment should be determined given the hypothesis that neural circuits underlying morality are compromised in antisocial individuals. KEYWORDS—brain imaging; genetics; antisocial; moral; treatment What specific genes predispose an individual to commit crime? How do they change brain processes to give rise to antisocial behavior? And what role does the environment play? While these questions may seem enigmatic, we are currently witnessing scientific advances that hold the promise of beginning to answer them and revolutionizing our understanding of antisocial, violent, and psychopathic behavior. The key concept highlighted in this review is that specific genes result in structural and functional brain alterations that, in turn, predispose to antisocial behavior. This article summarizes current research supporting this ‘‘genes to brain to antisocial behavior’’ hypothesis, places that knowledge into the context of the social environment, and explores wider neuroethical considerations for society and the criminal justice system. Antisocial behavior is here viewed as a dimension rather than as a category, and is defined as failure to conform to social norms for lawful behavior.