Antisocial personality traits linked to blunted brain responses to angry faces

A new neuroimaging study published in the Journal of Psychiatric Research has found that adults who report higher levels of antisocial personality traits show reduced brain responses to threatening social cues. Specifically, the study found that individuals with more symptoms of antisocial personality disorder, or ASPD, showed lower activation in brain regions involved in processing emotional and social information when confronted with angry faces appearing to loom toward them.

Antisocial personality disorder is typically characterized by a consistent disregard for the rights of others, often beginning in adolescence and persisting into adulthood. Individuals with ASPD tend to engage in behaviors that are impulsive, aggressive, and sometimes violent. While ASPD is sometimes confused with psychopathy, the two are not identical. Psychopathy includes emotional traits like callousness and shallow affect, while ASPD is primarily diagnosed based on observable antisocial behaviors.

People with ASPD are at increased risk of aggression, which can take the form of reactive aggression—impulsive responses to provocation—or goal-directed aggression intended to achieve a specific outcome. Past research has suggested that threat processing may play a role in both forms of aggression. For example, hypersensitivity to threat has been associated with reactive aggression, while a blunted response to threat may be linked to instrumental aggression. In either case, how individuals perceive and process social cues related to anger or danger may be central to their behavioral responses.

Much of the prior work in this area has focused on adolescents with conduct disorder or callous-unemotional traits. These studies have pointed to abnormalities in regions such as the amygdala and other parts of the brain involved in fear processing and emotion regulation. Less is known about how these systems function in adults with ASPD.

To explore this, the researchers recruited 54 men from Sichuan Province in China, including 27 violent offenders incarcerated at a judicial police hospital and 27 individuals from the general community. Participants completed a self-report questionnaire measuring ASPD symptoms and underwent brain scans while participating in a task designed to simulate social threat.

The task involved looking at photographs of faces displaying either angry or neutral expressions. These images were animated to appear as if they were either approaching (looming) or moving away (receding) from the viewer. Looming angry faces, in particular, were intended to evoke a sense of threat. Participants were asked to press a button as soon as they saw a face, which allowed researchers to measure their behavioral response times in addition to their brain activity.

The facial images were drawn from a validated database tailored for Chinese participants, and the angry and neutral expressions were matched for clarity and recognizability. The task was repeated over two scanning sessions, and the researchers analyzed brain responses using functional magnetic resonance imaging, or fMRI.

To assess the severity of antisocial traits, the researchers used a standardized subscale of the Personality Diagnostic Questionnaire. This measure asked participants to endorse statements such as “I enjoy taking risks” or “I have frequently engaged in physical fights.” ASPD scores were calculated based on how many such statements the individual endorsed.

While participants’ reaction times to the facial stimuli did not vary significantly based on emotion or movement direction, the brain scan data revealed a striking pattern. Individuals who scored higher on the ASPD scale showed significantly reduced neural responses when viewing looming angry faces, compared to looming neutral faces. This effect was most pronounced in three specific brain areas: the left superior temporal gyrus, the left inferior temporal gyrus, and the right ventral tegmental area.

The superior temporal gyrus is believed to play a role in understanding others’ mental states and interpreting social cues—a capacity sometimes referred to as Theory of Mind. The inferior temporal gyrus is involved in facial recognition, particularly in distinguishing facial identity and features. The ventral tegmental area is part of the brain’s reward and aversion system and is known to be responsive to emotionally salient stimuli, including those that are threatening.

Reduced activity in these regions when viewing threatening faces may suggest a diminished ability to recognize or respond to social signals that typically indicate potential danger or the need to adjust one’s behavior. This could help explain why some individuals with high levels of antisocial traits fail to avoid situations that lead to conflict or punishment.

The findings align with earlier studies in younger populations. For instance, adolescents with disruptive behavior problems and high levels of callous-unemotional traits tend to show similar patterns of reduced activity in brain regions related to empathy and threat detection. The present study suggests that this pattern may extend into adulthood and may be associated with self-reported antisocial behavior.

The ability to detect and respond to social threats plays an important role in regulating behavior. People who can quickly identify anger or disapproval in others are more likely to adjust their actions to avoid conflict or negative consequences. A reduced sensitivity to these cues, on the other hand, may contribute to aggressive or antisocial behavior by lowering the perceived risks of acting out.

From a clinical perspective, these findings point to the possibility of using brain-based measures to better identify individuals at heightened risk of aggression. The National Institute of Mental Health has proposed a research framework called the Research Domain Criteria, or RDoC, which encourages the integration of behavioral and biological data to improve psychiatric diagnosis. Under this framework, measures of threat processing might one day help refine assessments of antisocial tendencies.

The study also hints at potential directions for intervention. Training individuals with high levels of antisocial traits to better recognize facial expressions and emotional cues might help reduce aggressive behavior. Similar training programs have been explored in other populations, such as individuals with autism or social anxiety, though their effectiveness in ASPD remains to be tested.

There are some limitations that need to be considered. The sample size was relatively small, and the findings may not generalize beyond the specific population studied. Many of the participants were incarcerated, which may influence their responses in ways not fully accounted for. Additionally, the strength of the MRI scanner used was lower than the more commonly used 3T machines, which may have reduced the sensitivity of some measurements.

Another limitation is that the researchers relied on a self-report questionnaire to assess ASPD symptoms. While the tool is widely used, it does not capture the full clinical picture and cannot replace a formal diagnosis by a mental health professional.

The study also did not distinguish between different types of aggression. Individuals with ASPD may engage in both reactive aggression, which is impulsive and driven by emotional responses, and instrumental aggression, which is calculated and goal-directed. Future studies might explore how different forms of aggression relate to neural threat processing.

The study, “Negative correlation between level of self-reported antisocial personality disorder symptoms and neural responsiveness to looming threats,” was authored by Hui Zhao, R. James R. Blair, Huali Zhou, Changjian Zhai, Qianglong Wang, Yaran Zhang, Xinyu Ding, Ping Song, Zhuo Zhang, and Bo Yang.