The analysis of the prefrontal cortex and its facilitator role of violence: conclusions of a systematic review and meta-analysis based on neuroimaging results

The prefrontal cortex (PFC) is a key brain region for behavioral regulation; therefore, PFC abnormalities might partly be responsible for violence proneness. However, less is known about whether these alterations in PFC subregions are present in various types of individuals with a history of violent behaviors, including those who have committed violent crimes and those engaging in violent attacks against others, with or without mental or personality disorders. Therefore, the main objective of this review is to summarize the key findings from neuroimaging research that measures whether differences in the PFC exist between different samples of violent and criminal adults compared to non-violent individuals. It also examines the relationship between the PFC and violence-related concepts. A systematic review was conducted following the PRISMA quality criteria for reviews, using four digital databases and complemented with a snowballing search process. A total of 86 papers that met all the inclusion criteria were finally included. Most of these studies were conducted with men. Most individuals with histories of violent behavior (with and without mental and personality disorders) exhibited reduced volume in the orbitofrontal cortex compared to non-violent individuals. Other alterations included a lower synthesis of 5-HT in the OFC, along with higher levels of 5-HT2A receptors in the OFC and (dorsolateral PFC) DLPFC. However, these serotoninergic differences were only observed in a few groups of violent individuals, particularly those with high impulsivity. Violent individuals also exhibited different resting-state functional connectivity patterns between the OFC and lateral PFC (both dorsal and ventral) with the amygdala and cerebellum compared to non-violent individuals. This review specifies which PFC alterations may be generalizable and specific to different groups of violent individuals, with and without mental and personality disorders.