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Brain stimulation may reduce intent to commit violence
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Study findings published in The Journal of Neuroscience indicated that increasing activity in the prefrontal cortex using transcranial direct current stimulation can diminish a person’s intentions to commit aggressive acts and boost their perceptions of moral judgment.
"It was important to show experimentally that enhancing prefrontal activity can reduce aggressive intent and enhance moral judgment because prior neuroimaging and neuropsychological studies have largely only been able to make correlational rather than causal conclusions about the role of the prefrontal cortex on antisocial and aggressive behavior," Olivia Choy, PhD, from the department of psychology, Nanyang Technological University, Singapore, told Healio Psychiatry. "The study aimed to better understand the neural basis of violent behavior."
Researchers examined whether using transcranial direct current stimulation (tDCS) to stimulate the dorsolateral prefrontal cortex decreases the likelihood of performing aggressive acts, as well as the mechanism underlying this connection, in a double-blind, stratified, placebo-controlled, randomized trial.
They randomly allocated 39 adults to receive stimulation of the prefrontal cortex for 20 minutes (active condition) and 42 to receive a low current for 30 seconds (placebo condition), with follow-up 1 day after the experiment session. Participants were given two hypothetical situations after receiving stimulation, asking them to rate on a 0 to 10 scale the likelihood they would act as the protagonist in the vignettes, as well as perception of the moral wrongness of the aggressive acts, according to a related press release.
The results showed participants who received tDCS reported a significantly lower likelihood of engaging in aggression compared with the control group (P < .01). Further analyses demonstrated that adults in the active tDCS group also had a lower intent to commit physical assault and sexual assault (both P = .02).
The group receiving anodal stimulation perceived aggressive acts as more morally wrong compared with controls (P = .04); the main effect of treatment was significant regarding sexual assault, but not physical assault. The authors also found that perceptions of greater moral wrongfulness accounted for 31% of the total effect of tDCS on intention to commit aggression.
"This is an early step in the application of tDCS to better understand antisocial and aggressive behavior, and findings certainly need to be replicated and extended before practical applications are considered. However, the study may help inform future approaches to reducing aggressive intent and behavior through a non-invasive, relatively benign intervention that targets a biological risk factor for crime," Choy told Healio Psychiatry. "We should also note that the reductions produced by tDCS were limited to aggressive intent, rather than aggressive behavior. It might be that repeated sessions over a longer time period could produce changes in behavior. Nevertheless, this is a first step.” – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.
Editor's note: This article was updated on July 11 with comments from the study author.
Perspective
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Abhishek Jain, MD
Can electrode stimulation of certain brain regions decrease violent behavior? In a recently published study, Choy and colleagues examined whether transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) reduces intentions to commit aggression. While the experiment suggests increasing prefrontal brain activity via tDCS may offer a non-invasive intervention to reduce aggressive intent and improve moral perceptions of physical and sexual violence, the findings are far from conclusive.
As the researchers point out, this study is “a modest step towards advancing knowledge about the neural mechanisms that regulate aggression.” The study only administered a single session of tDCS, the sample size is not generalizable, the long-term impact (ie, beyond 1 day) on aggression is unknown, and specificity to the DLPFC brain region is undetermined. Moreover, although participants who received tDCS reported being less likely to engage in aggressive behavior, they actually demonstrated a slight, albeit non-significant, increase in aggressive behavior.
Overall, tDCS is still in an investigational stage, and its application in reducing violence is even less clear. Future studies are needed to replicate findings, investigate applicability to various populations, and further elucidate the neurological link between perception, intent, and action relating to physical aggression. Furthermore, social and ethical considerations, such as potential adverse outcomes in vulnerable individuals with psychiatric or neurologic illness, coercive use in legal settings, and the risk of false reassurance among high-risk violent offenders, need to be explored prior to the practical application of this intervention.
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