The world’s notorious criminals are known for perpetrating some of the most violent, gruesome crimes, such as the serial killer Ted Bundy from the 1970s. You may have heard the terms “sociopath” and “psychopath” referred to such individuals who commit illegal and even unusual acts. Despite how loosely these labels are often used, there are key differences between sociopathy and psychopathy.

Sociopathy is a broad term that refers to an individual who has Antisocial Personality Disorder (ASPD). According to the Diagnostic and Statistical Manual of Mental Disorders (DSM), which is the standard handbook used by clinicians and psychiatrists to assess and diagnose mental disorders, ASPD is characterized by the lack of conformity to social expectations by perpetrating antisocial behaviors that disregard or violate other people’s rights (Friedman et al., 2021).

Psychopathy involves characteristics similar to ASPD. However, psychopathy is specifically defined by two factors. Factor 1 describes the emotional and interpersonal dimension of psychopathy, which refers to the core personality traits that people may often associate with psychopathy: fearlessness, boldness, excitement-seeking, absence of empathy, lack of remorse, and manipulative (Crego & Widiger, 2022; Friedman et al., 2021). Factor 2 defines the impulsive and irresponsible dimension of psychopathy, which describes the antisocial lifestyle and socially deviant behavioral aspect (Friedman et al., 2021). Although the second factor of psychopathy overlaps with the diagnostic criteria of ASPD, the first factor is not observed in all individuals diagnosed with ASPD.

In other words, most people who exhibit psychopathy also meet the criteria for ASPD, but not all people diagnosed with ASPD show psychopathic traits (Baliousis et al., 2019).

Despite criticism and numerous research studies that have identified distinctions between ASPD and psychopathy, the DSM still fails to represent the differences between them (Baliousis et al., 2019). ASPD can be formally diagnosed, yet psychopathy remains a term to describe a set of traits—not an official clinical diagnosis.

As a fan of reading and learning about true crime, which is a genre that involves the analysis of real crime cases, and a student studying neuroscience, I wondered about the neuroscience behind the actions of criminals. What is going on inside their minds to perpetrate such crimes? Who can we label as a sociopath or psychopath? Studies have suggested differences in brain structure and functioning in individuals who meet the criteria for antisocial personality disorder and those who also meet the criteria for psychopathy (Baliousis et al., 2019; Gregory et al., 2012).

Structural and functional imaging of the brain suggest the important role of the ventromedial prefrontal cortex (vmPFC) and the amygdala (Gregory et al., 2012). The vmPFC is important for moral decision making, as well as emotional thoughts and behaviors in social settings (Baliousis et al., 2019). Meanwhile, the amygdala plays a key role in emotional processing, especially for aggression and fear (Gregory et al., 2012).

The connection between these two brain regions allows people to regulate their emotional reactions and behaviors to frustration and threats in the environment, particularly concerning other people’s distress (Waller et al., 2019). In a study with people at high risk for antisocial behavior, individuals who scored higher on a psychopathic traits scale had a significantly weakened connection between the vmPFC and amygdala when they viewed images of fearful faces than individuals who scored lower for psychopathic traits (Waller et al., 2019). In addition, criminals who demonstrated psychopathic traits had both reduced structural and functional connectivity of the vmPFC and amygdala than criminals who did not exhibit psychopathy (Motzkin et al., 2011).

Thus, offenders with psychopathic traits than those without psychopathic traits may have greater impairment of the vmPFC and amygdala, as well as their connectivity. Psychopaths’ absolutely fearless, remorseless traits and reactions toward other people compared to sociopaths may be explained by their inability to regulate emotions and behaviors through the vmPFC-amygdala.

Now to be clear, I am not putting the blame of criminals’ behaviors solely on the anatomy and wiring of their brains. Ted Bundy’s psychopathic crimes are inexcusable. However, it is important to consider his possibly impaired brain structure and function, especially in the vmPFC and amygdala, that may have contributed to his thoughts and behaviors toward others. The next time you come across a criminal case, it may be worth analyzing whether the perpetrator is truly a sociopath or psychopath.

References

Baliousis, M., Duggan, C., McCarthy, L., Huband, N., & Völlm, B. (2019). Executive function, attention, and memory deficits in antisocial personality disorder and psychopathy. Psychiatry Research, 278, 151–161. https://doi.org/10.1016/j.psychres.2019.05.046

Crego, C., & Widiger, T. A. (2022). Core traits of psychopathy. Personality Disorders: Theory, Research, and Treatment. https://doi.org/10.1037/per0000550

Friedman, N. P., Rhee, S. H., Ross, J. M., Corley, R. P., & Hewitt, J. K. (2021). Genetic and environmental relations of executive functions to antisocial personality disorder symptoms and psychopathy. International Journal of Psychophysiology, 163, 67–78. https://doi.org/10.1016/j.ijpsycho.2018.12.007

Gregory, S., Simmons, A., Kumari, V., Howard, M., Hodgins, S., & Blackwood, N. (2012). The antisocial brain: psychopathy matters: a structural MRI investigation of antisocial male violent offenders. Archives of General Psychiatry, 69(9), 962-972. https://doi.org/10.1001/archgenpsychiatry.2012.222

Motzkin, J. C., Newman, J. P., Kiehl, K. A., & Koenigs, M. (2011). Reduced prefrontal connectivity in psychopathy. Journal of Neuroscience, 31(48), 17348-17357. https://doi.org/10.1523/JNEUROSCI.4215-11.2011