N2 amplitude modulation across the antisocial spectrum: a meta-analysis

Despite the accumulated knowledge on antisocial behavior and the positive event-related potential peaking around 300 ms (P3), less is known about the preceding negative electrophysiological response around 200 ms (N2). A systematic search of the literature was conducted to analyze the N2 modulation across the antisocial spectrum. Thirty-seven studies (n =1199) were retrieved to the quantitative analysis. Reduced N2 amplitudes were found in the more severe antisocial manifestations (violent behavior and antisocial personality disorder), which is consistent with previous findings on P3 alterations and N2 reduced amplitudes in externalizing disorders. Findings on psychopathy were mixed, also in accordance with previous P3 results. From a dimensional lens, this supports the heterogeneity of the psychopathic personality structure: impulsivity features are a closer attribute of antisocial behavior and thus may be associated with N2 reduction, while adaptive psychopathic traits may be associated with intact (or even increased) N2 amplitude. The increased N2 amplitudes observed in impulsive behavior challenge, however, the previous meta-analytic findings. As most of the studies on impulsivity include subclinical samples, it leads to the hypothesis that some compensatory mechanisms can still occur at a subclinical level, reflecting the need for heightened allocation of brain resources to yield similar performances. Importantly, inhibition was the core deficit to explain N2 blunted amplitudes, alongside with deficits in the frontal brain region. From our findings, the reduction in P3 amplitude across the antisocial spectrum may be detected in the previous N2 time window.