New neuroscience research links psychopathy’s antisocial features to distinct brain structure abnormalities

A new study published in the European Archives of Psychiatry and Clinical Neuroscience provides evidence that individuals who exhibit psychopathic traits tend to show structural differences across widespread brain regions. Using advanced brain imaging techniques, researchers found that impulsive and antisocial behaviors—a core feature of psychopathy—are strongly associated with reduced volume in brain areas involved in behavioral regulation and self-control. In contrast, traits related to shallow emotions and manipulativeness appeared to show more variable and weaker associations with brain structure.

Psychopathy refers to a set of personality traits linked to a heightened risk of aggression, violence, and persistent antisocial behavior. People high in these traits often show a lack of empathy and remorse, combined with manipulative tendencies and emotional detachment. They also tend to exhibit impulsive, irresponsible behavior and a higher likelihood of criminal activity and reoffending. Unlike antisocial personality disorder, psychopathy is not formally classified as a clinical diagnosis in many diagnostic systems, but it remains a widely studied and influential construct in both forensic psychology and psychiatry.

Researchers commonly measure psychopathy using the Psychopathy Checklist–Revised, a 20-item assessment tool. It produces a total score along with two dimensions. The first, sometimes called the interpersonal-affective factor, reflects traits like superficial charm, deceitfulness, and emotional coldness. The second, known as the lifestyle-antisocial factor, captures traits such as impulsivity, poor behavioral controls, and a tendency toward antisocial actions. Although these two dimensions often co-occur, they represent distinct behavioral patterns and may involve different underlying brain mechanisms.

While previous research has linked psychopathy to structural brain differences, findings have varied considerably across studies. Some of the inconsistency may stem from small sample sizes, differences in assessment tools, or variability in the characteristics of the participants. Many studies have also relied on nonclinical populations—such as university students—to infer conclusions about psychopathy.

The new study aimed to overcome these limitations by analyzing neuroimaging data from a relatively large sample of forensic cases, focusing specifically on individuals with high psychopathy scores. The researchers wanted to examine whether the two dimensions of psychopathy—affective-interpersonal traits and antisocial behavior—show different patterns of brain structure abnormalities.

“Psychopathy is associated with aggressive and violent behaviour. Elucidating its neurobiological causes could help to find new strategies for therapy or early diagnosis, which is important because currently psychopathy of adults is considered to be difficult or impossible to treat,” said study author Peter Pieperhoff of the Institute of Neuroscience and Medicine at Forschungszentrum Jülich.

The study included 39 right-handed men with high psychopathy scores (20 or above on the Psychopathy Checklist–Revised). Participants were recruited from forensic hospitals and parole offices across three German sites. An age-matched group of control participants was also included for comparison. All participants were screened to exclude major psychiatric or neurological disorders, although substance use history was allowed, provided there was a period of abstinence prior to participation.

Each participant underwent a magnetic resonance imaging (MRI) scan. The researchers used a method called deformation-based morphometry to estimate the volumes of various brain regions. These estimates were then analyzed in relation to each participant’s psychopathy scores. The analysis employed the Julich-Brain Atlas, a detailed neuroanatomical mapping system, along with statistical methods designed to reduce false positives when examining multiple brain regions.

The most consistent finding was that individuals with high scores on the second dimension of psychopathy (impulsive and antisocial behavior) tended to show smaller volumes in several brain areas involved in behavioral control. These included structures within the brainstem, basal ganglia, and thalamus, as well as areas of the frontal cortex and cerebellum. Many of these regions play key roles in motor coordination, inhibition, decision-making, and emotional regulation.

Specifically, the researchers found reduced volumes in the subthalamic nucleus, substantia nigra, thalamic nuclei, and regions of the orbitofrontal cortex. These areas are part of frontal-subcortical circuits, which form feedback loops between the cortex and deeper brain structures. These loops are believed to be essential for regulating impulses, evaluating risks, and modulating emotions. The findings suggest that structural impairments in these networks may contribute to the impulsivity and antisocial tendencies seen in psychopathy.

“The clinical definition of psychopathy encompasses two groups of personality features: Interpersonal/affective and lifestyle/antisocial features,” Pieperhoff told PsyPost. “The latter group of features describes e.g. impulsive, irresponsible behaviour or criminal behavior. In our study, we found that increased scores of this feature group are associated with structural deficits, i.e. reduced volumes of specific brain regions, which are part of certain neuronal circuits. This finding is particularly interesting, because it is known that many brain functions are formed by similar circuits.”

In contrast, the first psychopathy dimension (interpersonal and affective traits) showed much weaker and more variable associations with brain structure. While a few small areas in the orbitofrontal cortex and hippocampus were positively or negatively linked to these traits, the results did not hold up after correcting for multiple comparisons.

This may indicate that these traits are either more behaviorally nuanced or less dependent on consistent structural alterations. Alternatively, the variability could reflect the presence of “successful psychopaths,” who score high on affective and interpersonal traits but manage to avoid overt criminal behavior and may even function effectively in society.

When comparing the brain scans of psychopathic individuals to controls, the researchers observed an overall reduction in total brain volume in the psychopathy group. The most prominent regional volume differences were found in the right subiculum, part of the hippocampus, which plays a role in memory and spatial navigation.

“The mean global brain volume of psychopathic subjects was lower than that of control subjects, which could indicate a disturbance of brain development in psychopathy.”

The researchers acknowledged several limitations. Although the sample size was larger than many previous studies, it was still relatively small given the complexity of the analyses. The psychopathy group came from forensic populations, which often include individuals with varying histories of substance use or cognitive impairment—factors that may also affect brain structure. Intelligence levels were not matched or measured across all participants, which may have introduced additional variability.

“It would be desirable to conduct more in-depth behavioural or psychological investigations of psychopathic subjects, in particular to disentangle their interpersonal/affective peculiarities,” Pieperhoff said.

Another limitation is that the study used structural imaging alone, without incorporating functional data. While changes in brain volume provide important clues, they do not fully capture how these brain regions operate during tasks involving emotion, inhibition, or decision-making. Future research could combine structural and functional imaging to better understand the dynamic processes involved in psychopathy.

“Our study suggests that some people might have more difficulties to behave in a socially adequate way because of certain deviations in their brain structure,” Pieperhoff noted. “But these findings neither relieve anyone of the responsibility for his/her own behaviour, nor do they answer the question what is an adequate protection against psychopathic criminals, recidivism or prevention of violent behaviour in a certain situation. In particular, the causes of these structural deviations of the brain was not answered by our study.”

Despite these limitations, the findings suggest that psychopathy—particularly its antisocial and impulsive features—is linked to disruptions in brain circuits responsible for behavioral regulation. The interpersonal and emotional traits of psychopathy may be less consistently tied to structural abnormalities, or they may involve more individualized patterns of brain differences. Further research is needed to determine how genetic, developmental, and environmental factors shape these neurobiological profiles, and whether they might be useful for clinical or forensic assessments in the future.

The study, “Associations of brain structure with psychopathy,” was authored by Peter Pieperhoff, Lena Hofhansel, Frank Schneider, Jürgen Müller, Katrin Amunts, Sabrina Weber-Papen, Carmen Weidler, Benjamin Clemens, Adrian Raine, and Ute Habel.