Prefrontal cortex structural and developmental associations with callous-unemotional traits and aggression.

Youths with high levels of callous-unemotional (CU) traits and aggression are at an increased risk for developing antisocial behaviours into adulthood. In this population, neurostructural grey matter abnormalities have been observed in the prefrontal cortex. However, the directionality of these associations is inconsistent, prompting some to suggest they may vary across development. Although similar neurodevelopmental patterns have been observed for other disorders featuring emotional and behavioural dysregulation, few studies have tested this hypothesis for CU traits, and particularly not for aggression subtypes. The current study sought to examine grey matter correlates of CU traits and aggression (including its subtypes), and then determine whether these associations varied by age. Fifty-four youths (10-19 years old) who were characterized for CU traits and aggression underwent MRI. Grey matter volume and surface area within the anterior cingulate cortex was positively associated with CU traits. The correlation between CU traits and medial orbitofrontal cortex (mOFC) volume varied significantly as a function of age, as did the correlation between reactive aggression and mOFC surface area. These associations became more positive with age. There were no significant findings for proactive/total aggression. Results are interpreted considering the potential for delayed cortical maturation in youths with high CU traits/aggression.

Brain structural correlates of psychopathic traits in elite female combat-sports athletes.

Psychopathy is characterized by glibness and superficial charm, as well as a lack of empathy, guilt and remorse, and is often accompanied by antisocial behaviour. The cerebral bases of this syndrome have been mostly studied in violent subjects or those with a criminal history. However, the antisocial component of psychopathy is not central to its conceptualization, and in fact, psychopathic traits are present in well-adjusted, non-criminal individuals within the general population. Interestingly, certain psychopathy characteristics appear to be particularly pronounced in some groups or professions. Importantly, as these so-called adaptive or successful psychopaths do not show antisocial tendencies or have significant psychiatric comorbidities, they may represent an ideal population to study this trait. Here, we investigated such a group, specifically elite female judo athletes, and compared them with matched non-athletes. Participants completed psychopathy, anger, perspective-taking and empathic concern questionnaires and underwent structural magnetic resonance imaging (MRI). Grey matter volume (GMV) was computed using voxel-based morphometry from the T1-weighted images. Athletes scored significantly higher in primary psychopathy and anger and lower in empathy and perspective taking. They also exhibited smaller GMV in the right temporal pole, left occipital cortex and left amygdala/hippocampus. GMV values for the latter cluster significantly correlated with primary psychopathy scores across both groups. These results confirm and extend previous findings to a little-studied population and provide support for the conceptualization of psychopathy as a dimensional personality trait which not only is not necessarily associated with antisocial behaviour but may potentially have adaptive value.

Connectome-based predictive modeling of empathy in adolescents with and without the low-prosocial emotion specifier.

Empathy impairments are an important part of a broader affective impairments defining the youth antisocial phenotype callous-unemotional (CU) traits and the DSM-5 low prosocial emotion (LPE) specifier. While functional connectivity underlying empathy and CU traits have been well studied, less is known about what functional connections underly differences in empathy amongst adolescents qualifying for the LPE specifier. Such information can provide mechanistic distinctions for this clinically relevant specifier. The present study uses connectome-based predictive modeling that uses whole-brain resting-state functional connectivity data to predict cognitive and affective empathy for those meeting the LPE specifier (n = 29) and those that do not (n = 57). Additionally, we tested if models of empathy generalized between groups as well as density differences for each model of empathy between groups. Results indicate the LPE group had lower cognitive and affective empathy as well as higher CU traits and conduct problems. Negative and positive models were identified for affective empathy for both groups, but only the negative model for the LPE and positive model for the normative group reliably predicted cognitive empathy. Models predicting empathy did not generalize between groups. Density differences within the default mode, salience, executive control, limbic, and cerebellar networks were found as well as between the executive control, salience, and default mode networks. And, importantly, connections between the executive control and default mode networks characterized empathy differences the LPE group such that more positive connections characterized cognitive differences and less negative connections characterized affective differences. These findings indicate neural differences in empathy for those meeting LPE criteria that may explain decrements in empathy amongst these youth. These findings support theoretical accounts of empathy decrements in the LPE clinical specifier and extend them to identify specific circuits accounting for variation in empathy impairments. The identified negative models help understand what connections inhibit empathy whereas the positive models reveal what brain patterns are being used to support empathy in those with the LPE specifier. LPE differences from the normative group and could be an appropriate biomarker for predicting CU trait severity. Replication and validation using other large datasets are important next steps.

Effects of Substance Use and Antisocial Personality on Neuroimaging-Based Machine Learning Prediction of Schizophrenia.

BACKGROUND AND HYPOTHESIS: Neuroimaging-based machine learning (ML) algorithms have the potential to aid the clinical diagnosis of schizophrenia. However, literature on the effect of prevalent comorbidities such as substance use disorder (SUD) and antisocial personality (ASPD) on these models' performance has remained unexplored. We investigated whether the presence of SUD or ASPD affects the performance of neuroimaging-based ML models trained to discern patients with schizophrenia (SCH) from controls. STUDY DESIGN: We trained an ML model on structural MRI data from public datasets to distinguish between SCH and controls (SCH = 347, controls = 341). We then investigated the model's performance in two independent samples of individuals undergoing forensic psychiatric examination: sample 1 was used for sensitivity analysis to discern ASPD (N = 52) from SCH (N = 66), and sample 2 was used for specificity analysis to discern ASPD (N = 26) from controls (N = 25). Both samples included individuals with SUD. STUDY RESULTS: In sample 1, 94.4% of SCH with comorbid ASPD and SUD were classified as SCH, followed by patients with SCH + SUD (78.8% classified as SCH) and patients with SCH (60.0% classified as SCH). The model failed to discern SCH without comorbidities from ASPD + SUD (AUC = 0.562, 95%CI = 0.400-0.723). In sample 2, the model's specificity to predict controls was 84.0%. In both samples, about half of the ASPD + SUD were misclassified as SCH. Data-driven functional characterization revealed associations between the classification as SCH and cognition-related brain regions. CONCLUSION: Altogether, ASPD and SUD appear to have effects on ML prediction performance, which potentially results from converging cognition-related brain abnormalities between SCH, ASPD, and SUD.

Psychopathic traits and social brain responses during moral evaluation in adolescence.

Brain functioning underlying moral decision-making in adolescents with psychopathic traits is relatively less understood. This fMRI study examined the neural correlates of moral decision-making in relation to psychopathic traits, as measured by the Youth Psychopathic Traits Inventory (YPI), in a sample of 16 community-recruited youth (mean age=13.94) with reported behavior problems. Participants viewed images that depicted a moral violation, a conflict with no moral violation, and a neutral scenario. We analyzed activation, seed-to-voxel, and seed-to-seed functional connectivity using a social brain mask during moral reasoning and decision-making. Results indicated: a) greater activity in social brain regions while assessing acts of moral, compared to nonmoral, violations; b) positive correlations between activation of several social brain regions and YPI subscale scores; c) a positive association between YPI and functional connectivity between the social brain network and the bilateral middle cingulate cortices; d) significant effects of YPI on connectivity between social brain regions and the rest of the brain; and e) decreased connectivity between several ROIs during moral reasoning: the left temporoparietal junction (lTPJ) and dorsomedial prefrontal cortex (DMPFC), the precuneus (PREC) and left amygdala (lAMYG), and the PREC and rAMYG. Clinical and developmental implications of these findings are discussed.

Larger left hippocampal presubiculum is associated with lower risk of antisocial behavior in healthy adults with childhood conduct history.

Conduct Disorder (CD) is defined as aggressive, antisocial, and rule-breaking behavior during childhood. It is a major risk factor for developing antisocial personality disorder (ASPD) in adulthood. However, nearly half the CDs do not develop ASPD. Identification of reversion factors seems crucial for proper interventions. We identified 40 subjects with childhood history of CD (CC) and 1166 control subjects (HC) from Human Connectome Project. Their psychiatric, emotional, impulsivity, and personality traits were extracted. An emotion recognition task-fMRI analysis was done. We also did subregion analysis of hippocampus and amygdala in 35 CC and 69 demographically matched HCs. CC subjects scored significantly higher in antisocial-related evaluations. No differences in task-fMRI activation of amygdala and hippocampus were observed. CCs had larger subfields of the left hippocampus: presubiculum, CA3, CA4, and dentate gyrus. Further, an interaction model revealed a significant presubiculum volume × group association with antisocial, aggression, and agreeableness scores. Our study shows that healthy young adults with a prior history of CD still exhibit some forms of antisocial-like behavior with larger left hippocampal subfields, including presubiculum that also explains the variability in antisocial behavior. These larger left hippocampal subfield volumes may play a protective role against CD to ASPD conversion.

Resting-state connectivity underlying cognitive control's association with perspective taking in callous-unemotional traits.

Callous-Unemotional (CU) traits are often associated with impairments in perspective taking and cognitive control (regulating goal directed behavior); and adolescents with CU traits demonstrate aberrant brain activation/connectivity in areas underlying these processes. Together cognitive control and perspective taking are thought to link mechanistically to explain CU traits. Because increased cognitive control demands modulate perspective taking ability among both typically developing samples and individuals with elevated CU traits, understanding the neurophysiological substrates of these constructs could inform efforts to alleviate societal costs of antisocial behavior. The present study uses GIMME to examine the heterogenous functional brain properties (i.e., connection density, node centrality) underlying cognitive control's influence on perspective taking among adolescents on a CU trait continuum. Results reveal that cognitive control had a negative indirect association with CU traits via perspective taking; and brain connectivity indirectly associated with lower CU traits - specifically the social network via perspective taking and conflict network via cognitive control. Additionally, less negative connection density between the social and conflict networks was directly associated with higher CU traits. Our results support the growing literature on cognitive control's influence on socio-cognitive functioning in CU traits and extends that work by identifying underlying functional brain properties.

Oxytocin effects on amygdala reactivity to angry faces in males and females with antisocial personality disorder.

The amygdala is a key region in current neurocircuitry models of reactive aggression as it is crucially involved in detecting social threat and provocation. An increased amygdala reactivity to angry faces has been reported in aggression-prone individuals and the neuropeptide oxytocin (OT) could dampen anger-related amygdala reactivity in a number of mental disorders. One example is the antisocial personality disorder (ASPD) which has so far only been studied in limited numbers. To address the question whether OT can normalize amygdala hyperreactivity to emotional faces, we conducted a functional magnetic resonance imaging experiment with 20 men and 18 women with ASPD and 20 male and 20 female healthy control (HC) participants in a double-blind, randomized, placebo (PLC)-controlled within-subject design. Participants were exposed to an emotion classification task (fearful, angry, and happy faces) after receiving an intranasal dose (24 IU) of synthetic OT or PLC. We found OT to attenuate right amygdala hyperactivity to angry faces in participants with ASPD to such an extent that the intensity of amygdala activity in the ASPD group in the OT condition decreased to the level of amygdala activity in the PLC condition in the HC group. There was also a trend that OT effects were generally larger in women than in men. These findings suggest that OT differentially modulates the amygdala following social threatening or provoking cues in dependence of psychopathology (ASPD vs. HC) and sex (male vs. female). Particularly female ASPD patients could benefit from OT in the treatment of reactive aggression.

Antisocial behavior is associated with reduced frontoparietal activity to loss in a population-based sample of adolescents.

BACKGROUND: Adolescent antisocial behavior (AB) is a public health concern due to the high financial and social costs of AB on victims and perpetrators. Neural systems involved in reward and loss processing are thought to contribute to AB. However, investigations into these processes are limited: few have considered anticipatory and consummatory components of reward, response to loss, nor whether associations with AB may vary by level of callous-unemotional (CU) traits. METHODS: A population-based community sample of 128 predominantly low-income youth (mean age = 15.9 years; 42% male) completed a monetary incentive delay task during fMRI. A multi-informant, multi-method latent variable approach was used to test associations between AB and neural response to reward and loss anticipation and outcome and whether CU traits moderated these associations. RESULTS: AB was not associated with neural response to reward but was associated with reduced frontoparietal activity during loss outcomes. This association was moderated by CU traits such that individuals with higher levels of AB and CU traits had the largest reductions in frontoparietal activity. Co-occurring AB and CU traits were also associated with increased precuneus response during loss anticipation. CONCLUSIONS: Findings indicate that AB is associated with reduced activity in brain regions involved in cognitive control, attention, and behavior modification during negative outcomes. Moreover, these reductions are most pronounced in youth with co-occurring CU traits. These findings have implications for understanding why adolescents involved in AB continue these behaviors despite severe negative consequences (e.g. incarceration).

Mirror neurons and empathy-related regions in psychopathy: Systematic review, meta-analysis, and a working model.

Mirror neurons have been associated with empathy. People with psychopathic traits present low levels of empathy. To analyze this, a systematic review of fMRI studies of people with psychopathic traits during an emotional facial expression processing task was performed. The regions of interest were structures associated with the mirror neuron system: ventromedial prefrontal cortex (vmPFC), inferior parietal lobe (IPL), inferior frontal gyrus and superior temporal sulcus. The analysis was also extended to structures related to affective empathy (insula, amygdala and anterior cingulate cortex) and to two more emotional processing areas (orbitofrontal cortex and fusiform gyrus). Hypoactivation was more frequently observed in regions of the mirror neuron system from people with high psychopathic traits, as well as in the emotional processing structures, and those associated with affective empathy, except for the insula, where it presented higher activity. Differences were observed for all types of emotions. The results suggest that the mirror neuron system is altered in psychopathy and their relationship with affective empathy deficits is discussed.

How reliable are amygdala findings in psychopathy? A systematic review of MRI studies.

The amygdala is a key component in predominant neural circuitry models of psychopathy. Yet, after two decades of neuroimaging research on psychopathy, the reproducibility of amygdala findings is questionable. We systematically reviewed MRI studies (81 of adults, 53 of juveniles) to determine the consistency of amygdala findings across studies, as well as within specific types of experimental tasks, community versus forensic populations, and the lowest- versus highest-powered studies. Three primary findings emerged. First, the majority of studies found null relationships between psychopathy and amygdala structure and function, even in the context of theoretically relevant tasks. Second, findings of reduced amygdala activity were more common in studies with low compared to high statistical power. Third, the majority of peak coordinates of reduced amygdala activity did not fall primarily within the anatomical bounds of the amygdala. Collectively, these findings demonstrate significant gaps in the empirical support for the theorized role of the amygdala in psychopathy and indicate the need for novel research perspectives and approaches in this field.

The age of violence: Mapping brain age in psychosis and psychopathy.

Young chronological age is one of the strongest predictors for antisocial behaviour in the general population and for violent offending in individuals with psychotic disorders. An individual's age can be predicted with high accuracy using neuroimaging and machine-learning. The deviation between predicted and chronological age, i.e., brain age gap (BAG) has been suggested to reflect brain health, likely relating partly to neurodevelopmental and aging-related processes and specific disease mechanisms. Higher BAG has been demonstrated in patients with psychotic disorders. However, little is known about the brain-age in violent offenders with psychosis and the possible associations with psychopathy traits. We estimated brain-age in 782 male individuals using T1-weighted MRI scans. Three machine learning models (random forest, extreme gradient boosting with and without hyper parameter tuning) were first trained and tested on healthy controls (HC, n = 586). The obtained BAGs were compared between HC and age matched violent offenders with psychosis (PSY-V, n = 38), violent offenders without psychosis (NPV, n = 20) and non-violent psychosis patients (PSY-NV, n = 138). We ran additional comparisons between BAG of PSY-V and PSY-NV and associations with Positive and Negative Syndrome Scale (PANSS) total score as a measure of psychosis symptoms. Psychopathy traits in the violence groups were assessed with Psychopathy Checklist-revised (PCL-R) and investigated for associations with BAG. We found significantly higher BAG in PSY-V compared with HC (4.9 years, Cohen'sd = 0.87) and in PSY-NV compared with HC (2.7 years, d = 0.41). Total PCL-R scores were negatively associated with BAG in the violence groups (d = 1.17, p < 0.05). Additionally, there was a positive association between psychosis symptoms and BAG in the psychosis groups (d = 1.12, p < 0.05). While the significant BAG differences related to psychosis and not violence suggest larger BAG for psychosis, the negative associations between BAG and psychopathy suggest a complex interplay with psychopathy traits. This proof-of-concept application of brain age prediction in severe mental disorders with a history of violence and psychopathy traits should be tested and replicated in larger samples.

The implications of frontotemporal dementia for brain dysfunction in psychopathy.

Understanding how psychopathy compares with brain disease can help clarify its underlying mechanisms. This literature review is a broad overview of the neurobiology of psychopathic traits in comparison to behavioral variant frontotemporal dementia (bvFTD), a disorder uniquely associated with criminal behavior. In addition to violation of social norms, both psychopathy and bvFTD result in impaired socioemotional perception and empathy, impulsivity, and altered moral judgment. Despite wide areas of decreased function in psychopathy, structural changes are primarily evident in amygdala and, to a lesser extent, anterior insula, whereas in bvFTD neuropathology involves a wider paralimbic region. In psychopathy, relatively intact medial prefrontal and anterior cingulate cortices facilitate theory of mind and psychopathic traits such as deceitfulness and manipulation, bold fearlessness, and risk-taking behavior. In conclusion, many frontotemporal areas are hypoactive in psychopathy and bvFTD, but differences in dysfunctional connectivity in psychopathy vs. direct involvement in bvFTD potentially explain similarities and differences between these two conditions.

Larger striatal volume is associated with increased adult psychopathy.

Prior studies have inconsistently reported increased volumes of the striatum in adults with psychopathy. A meta-analysis presented here indicates an overall effect size of d = 0.44. Nevertheless, variability in findings exist, and questions remain on confounding clinical conditions and generalizability to females. This study tests the hypothesis that striatal volumes are increased in adults with psychopathic traits, and that this relationship is mediated by stimulation-seeking and impulsivity. Striatal volume was assessed using magnetic resonance imaging in 108 adult community-dwelling males alongside psychopathy using the Psychopathy Checklist - Revised. Subsidiary, exploratory analyses were conducted on a small sample of females. Correlational analyses showed that increased striatal volumes were associated with more psychopathic traits (p = .001). Effects were observed for all striatal regions, controlling for age, substance dependence and abuse, antisocial personality disorder, attention deficit hyperactivity disorder, social adversity, and total brain volume. An analysis of 18 psychopathic individuals showed that striatal volumes were increased 9.4% compared with 18 matched controls (p = .01). Psychopathy in females was also significantly associated with increased striatal volume (p = .02). Stimulation-seeking and impulsivity partly mediated the striatal-psychopathy relationship, accounting for 49.4% of this association. Findings from these two samples replicate and build on initial studies indicating striatal enlargement in adults with psychopathy, yielding an updated effect size of d = 0.48. Results are consistent with the notion that striatal abnormalities in individuals with psychopathy partly reflect increased sensation-seeking and impulsivity, and support the hypothesis of abnormal reward processing in psychopathy.

Altered effective connectivity from the posterior insula to the amygdala mediates the relationship between psychopathic traits and endorsement of the Harm foundation.

Psychopathic traits have been demonstrated to be associated with different moral foundations. However, the neuropsychological mechanism underlying the relationship between psychopathic traits and moral foundations remains obscure. Our study examined the effective connectivity (EC) of psychopathy-related brain regions and its association with endorsement to moral foundations (Harm, Fairness, Loyalty, Authority, and Purity)-combining questionnaire measures, resting-state fMRI (RS-fMRI), and Granger causality analysis. We administered the Levenson Self-Report Psychopathy Scale and Moral Foundation Questionnaire to 78 college students after RS-fMRI scanning. Our results showed that total and primary psychopathy negatively predicted endorsement of the Harm foundation. The EC from the posterior insula to the amygdala was negatively associated with primary psychopathy but positively associated with endorsement of the Harm foundation. Altered posterior insula-amygdala EC partially mediated the relationship between primary psychopathy and endorsement of the Harm foundation. Our findings demonstrated that individuals with elevated psychopathic traits may have atypical processes in recognizing and integrating bodily state information into emotional responses -leading to less concern for harm-related morality. Our findings deepen the understanding of the neuropsychological mechanism underlying the relationship between psychopathic traits and morality, providing potential neurobiological explanations for increased moral transgressions, especially those harm-related transgressions, committed by psychopathic individuals.

Sex matters: association between callous-unemotional traits and uncinate fasciculus microstructure in youths with conduct disorder.

Among youths with conduct disorder, those with callous-unemotional traits are at increased risk for persistent antisocial behaviour. Although callous-unemotional traits have been found to be associated with white-matter brain abnormalities, previous diffusion imaging studies were conducted in small samples, preventing examination of potential sex by callous-unemotional traits interaction effects on white matter. Here, we used tract-based spatial statistics at a whole-brain level and within regions of interest to compare the white matter correlates of callous-unemotional traits in female vs. male youths with conduct disorder, in a sample (n = 124) recruited through a multi-site protocol. A sex-specific association between callous-unemotional traits and white matter was found in the left uncinate fasciculus, where callous-unemotional traits were positively associated with axial diffusivity in males, while an opposite pattern was found in females. These findings are in line with previous studies suggesting that the uncinate fasciculus is a key tract implicated in the development of psychopathy, but also add to recent evidence showing that sexual dimorphism needs to be taken into account when examining the structural correlates of mental disorders in general, and callous-unemotional traits in conduct disorder in particular.

A multidimensional examination of psychopathy traits and gray matter volume in adults.

Uncovering the neurobiological abnormalities that may contribute to the manifestation of psychopathic traits is an important step toward understanding the etiology of this disorder. Although many studies have examined gray matter volume (GMV) in relation to psychopathy, few have examined how dimensions of psychopathic traits interactively relate to GMV, an approach that holds promise for parsing heterogeneity in neurobiological risk factors for this disorder. The aim of this study was to investigate the affective-interpersonal (Factor 1) and impulsive-antisocial (Factor 2) dimensions of psychopathy in relation to cortical surface and subcortical GMV in a mixed-gender, high-risk community sample with significant justice-system involvement (N = 156, 50.0% men). Cortex-wide analysis indicated that (i) the Factor 1 traits correlated negatively with GMV in two cortical clusters, one in the right rostral middle frontal region and one in the occipital lobe, and (ii) the interaction of the affective-interpersonal and impulsive-antisocial traits was negatively associated with GMV bilaterally in the parietal lobe, such that individuals high on both trait dimensions evidenced reduced GMV relative to individuals high on only one psychopathy factor. An interactive effect also emerged for bilateral amygdalar and hippocampal GMV, such that Factor 1 psychopathic traits were significantly negatively associated with GMV only at high (but not low) levels of Factor 2 traits. Results extend prior research by demonstrating the neurobiological correlates of psychopathy differ based on the presentation of Factor 1 and 2 traits.

Connectome-based model predicts individual psychopathic traits in college students.

BACKGROUND: Psychopathic traits have been suggested to increase the risk of violations of socio-moral norms. Previous studies revealed that abnormal neural signatures are associated with elevated psychopathic traits; however, whether the intrinsic network architecture can predict psychopathic traits at the individual level remains unclear. METHODS: The present study utilized connectome-based predictive modeling (CPM) to investigate whether whole-brain resting-state functional connectivity (RSFC) can predict psychopathic traits in the general population. Resting-state fMRI data were collected from 84 college students with varying psychopathic traits measured by the Levenson Self-Report Psychopathy Scale (LSRP). RESULTS: Functional connections that were negatively correlated with psychopathic traits predicted individual differences in total LSRP and secondary psychopathy score but not primary score. Particularly, nodes with the most connections in the predictive connectome anchored in the prefrontal cortex (e.g., anterior prefrontal cortex and orbitofrontal cortex) and limbic system (e.g., anterior cingulate cortex and insula). In addition, the connections between the occipital network (OCCN) and cingulo-opercular network (CON) served as a significant predictive connectome for total LSRP and secondary psychopathy score. CONCLUSION: CPM constituted by whole-brain RSFC significantly predicted psychopathic traits individually in the general population. The brain areas including the prefrontal cortex and limbic system and large-scale networks including the CON and OCCN play special roles in the predictive model-possibly reflecting atypical cognitive control and affective processing for individuals with elevated psychopathic traits. These findings may facilitate detection and potential intervention of individuals with maladaptive psychopathic tendency.

Associations between amygdala nuclei volumes, psychosis, psychopathy, and violent offending.

The amygdala is involved in fear perception and aggression regulation, and smaller volumes have been associated with psychotic and non-psychotic violence. We explored the relationship between amygdala nuclei volumes in violent offenders with and without psychosis, and the association to psychopathy traits. 3T MRI scans (n = 204, males, 18-66 years) were obtained from psychotic violent offenders (PSY-V, n = 29), non-psychotic violent offenders (NPV, n = 19), non-violent psychosis patients (PSY-NV, n = 67), and healthy controls (HC, n = 89). Total amygdala and 9 amygdala nuclei volumes were obtained with FreeSurfer. Psychopathy traits were measured with the Psychopathy Checklist-revised (PCL-R). Multivariate analyses explored diagnostic differences in amygdala nuclei volumes and associations to psychosis, violence, and psychopathy traits. PSY-V had a smaller basal nucleus, anterior amygdaloid area, and cortical amygdalar transition area (CATA), whereas PSY-NV had a smaller CATA than HC. Volumes in NPV did not differ from HC, and there were no associations between PCL-R total or factor scores and any of the nuclei or whole amygdala volumes. The lower volumes of amygdala nuclei involved in fear modulation, stress responses, and social interpretation may point towards some mechanisms of relevance to violence in psychosis, but the results warrant replication in larger subject samples.