Brain alterations potentially associated with aggression and terrorism

Abstract

A large proportion of the persons who join terrorist groups as well as lone-acting terrorists have a history of violent behavior or mental disorder that predated their becoming terrorists. This suggests that brain alterations found to occur in violent perpetrators may also be present in a significant percentage of terrorists. After a short delineation of phylogenetically old neuronal networks that are important for the generation of aggressive behavior in inconspicuous brains, this review summarizes structural and functional brain-imaging studies in violent offenders published over the last 10 years. Depending on the subtype of violence (impulsive or instrumental), deviations in structure or function were mainly found in the prefrontal, orbitofrontal, and insular cortex, as well as in temporolimbic structures (e.g., the amygdala, hippocampus, and parahippocampus). These brain areas are essentially responsible for the control of the archaic neuronal generators of aggression located in the hypothalamus and limbic system. This regional distribution of brain alterations also shows a remarkable overlap with those brain regions that are crucial for such prosocial traits as empathy and compassion. Feelings of superiority, dominance, and satisfaction gained by performing violent and terroristic attacks suggest that a hedonistic component via an activation of brain reward systems plays an additional role. In our current debate about the causes of terrorism, aspects of brain dysfunction should receive more attention.

Serotonergic Contributions to Human Brain Aggression Networks

“…In a similar vein, reduced gray matter in amygdala and PFC regions including the OFC have consistently been associated with trait aggression as well (Ermer et al, 2012). Functional neuroimaging studies corroborate the relevance of this frontolimbic system for the control of aggressive impulses; specifically, reduced IFG-amygdala connectivity is frequently observed in overly aggressive individuals (see Bogerts et al, 2018, for a review). Similar findings have also been obtained for the OFC; amygdala-OFC connectivity shows a negative association with trait anger (Fulwiler et al, 2012).…”

Terrorism and mental illness: a pragmatic approach for the clinician

“…Bogerts et al ’s (2018) review of violent offenders also found structural and functional abnormalities in brain regions crucial for empathy and compassion. Similar deficits have been found in individuals with antisocial personality disorder (Blair 2005; Marazziti 2013), and Marazziti (2016) has proposed that psychopathy could be a starting point for researchers trying to make sense of possible psychological profiles and features of terrorists.…”

“…Recent studies have revealed various socio-environmental and neurobiological factors associated with terrorist behaviour (Box 2).

Socio-environmental and neurobiological factors associated with terrorist behaviour Socio-environmental factors Socio-environmental risk factors that predispose a person to terrorism include (Campelo 2018): family dysfunctionfriendships with radicalised individualsunstable geopolitical environmentsocietal polarisation (unequal socio-economic conditions in the country) Neurobiological factors Violent offenders were found to have the following (Bogerts 2018): decreased grey matter in the orbitofrontal and prefrontal cortexdecreased volume of all temporolimbic structures and the posterior cingulate cortexreduced functional connectivity between the frontal cortex and the limbic areas, anterior insula and posterior cingulate cortexStructural and functional deficits in brain regions crucial for empathy and compassion, similar to those in individuals with antisocial personality disorder, have also been found (Blair 2005; Marazziti 2013).

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“…Violent offenders were found to have the following (Bogerts 2018): decreased grey matter in the orbitofrontal and prefrontal cortexdecreased volume of all temporolimbic structures and the posterior cingulate cortexreduced functional connectivity between the frontal cortex and the limbic areas, anterior insula and posterior cingulate cortexStructural and functional deficits in brain regions crucial for empathy and compassion, similar to those in individuals with antisocial personality disorder, have also been found (Blair 2005; Marazziti 2013). …”

“…A recent review of structural and functional brain imaging studies in violent offenders over the past 10 years by Bogerts et al (2018) offers a glimpse into the possible neurobiological factors specific to terrorists. They concluded that, among violent offenders who exhibited proactive violence (a subtype of violence the authors believe to be more applicable to terrorists), there was decreased grey matter in the orbitofrontal and prefrontal cortex, and decreased volume of all temporolimbic structures and the posterior cingulate cortex.…”