The effects of comorbid psychopathy

Personality Disorders: Theory, Research, and Treatments

Criminal Behavior and Cognitive Processing in Male Offenders With Antisocial Personality Disorder With and Without Comorbid Psychopathy

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Topic: Effects of Comorbid Psychopathy


Antisocial personality disorder (ASPD) and psychopathy are two syndromes which are effective in predicting antisocial behavior and identifying dangerous subsets of criminal offenders (Serin, 1991). The distinction between both disorders is often blurred, with DSM-IV–TR suggesting that ASPD and psychopathy can be used interchangeably (American Psychiatric Association, 2006). The two syndromes share important correlates, which does raise the distinct possibility that both ASPD and psychopathy may reflect the same underlying disorder. Conversely, there is evidence that suggests that both syndromes contrast with regards to cognitive and affective correlates. Individuals with psychopathy display adequate cognitive functioning under normal conditions but performance suffers on a variety of cognitive tasks when heavy demand is placed on the brain’s Left Hemisphere (LH); deficits not associated with ASPD (Llanes & Kosson, 2006). Prior research has also revealed that individuals with both ASPD and psychopathy exhibit greater criminal activity and weaker affective facilitation than those with ASPD only, suggesting the notion that a qualitative distinction exists between ASPD and psychopathy (Kosson, Lorenz, & Newman, 2006). Consequently, it is uncertain if the two disorders reflect the same underlying pathophysiologies, whether they are two distinct syndromes, or whether one is simply a more severe expression of the other.

The current study was carried out to address this issue and it does so by measuring the variance in criminal behavior and cognitive processing in an independent sample with regards to the presence of ASPD with versus without comorbid psychopathy. The study, which utilized six-hundred-and-seventy-four [674] male inmates of an Illinois county jail as its sample, was subdivided into two portions; the first which measured criminal behavior based on participant’s prior criminal records and the second which utilized data from a global-local processing task (conducted on a prior occasion) as a laboratory measure of cognitive processing. Participants exhibited either ASPD and comorbid psychopathy, ASPD but not psychopathy, or neither ASPD nor psychopathy.

Associated Theories

The criminal behavior analysis was conducted under the supposition that the presence of ASPD with comorbid psychopathy in participants would exhibit more severe and varied criminal histories when compared to control or participants with ASPD only. For the cognitive processing portion of the study, the LHA hypothesis was utilized. This theory predicts that psychopaths will display general cognitive ineptness and will respond more slowly than non-psychopaths when primary LH processing systems, specifically the attention, motor, language, and perceptual systems, are substantially and differentially activated.


The study evaluates three perspectives. The primary hypothesis of the experiment (H1: ASPD with and without comorbid psychopathy are disorders characterized by distinctly different underlying mechanisms) would be proven if ASPD with and without psychopathy reveal different patterns of performance in cognitive processing and show differences in criminal behavior. If both groups manifest similar measures of both criminal behavior and cognitive processing, it provides evidence for the null hypothesis (H0: ASPD with and without comorbid psychopathy are disorders that reflect the same underlying mechanism). The study also specifies a co-primary hypothesis (H2: ASPD with and without comorbid psychopathy are disorders that are distinct only in their severity) where criminal behavior and cognitive task performance impairments differ only in degree.

Sample and Selection Procedure

A stringent criterion was utilized in the selection of the six-hundred-and-seventy-four [674] detainees of an Illinois county jail whom comprised the primary sample used for the study. One-hundred-and-fifty-six [156] men from this primary sample, all whom had previously completed the global-local task, further comprised a secondary sub-sample which was used in the analyses of cognitive processing. In accordance to the inclusion criteria, all subjects were eighteen [18] – forty-five [45] year old males who had estimated IQ levels above seventy [70], could read English, were informed about their prior criminal histories, did not currently take medication that displayed neurocognitive side effects, did not exhibit psychotic symptoms, and were right handed (for analyses of cognitive processing task). Before being classified into groups, the primary sample was subject to a series of interviews and evaluations in order for diagnosis of the relevant disorders. Following an in-depth interview and review of available files, the Hare Psychopathy Checklist – Revised (PCL-R) was used to assess the presence of psychopathy in the participants. Inmates had to score at least 30/40 to be diagnosed with the disorder. PCL-R scores were slightly modified in order to avoid overlap between psychopathy scores and antisocial behavior The DSM-IV diagnostic criterion was used to assess ASPD. Following an interview and a review of available file material, inmates had to display at least 3 of 7 symptoms be diagnosed with the disorder. Inmates were then subdivided into one of three groups: ASPD with comorbid psychopathy (ASPD + PSY; n = 145), ASPD without comorbid psychopathy (ASPD-only; n = 201), and neither ASPD nor psychopathy (controls; n = 328). Outliers in both portions of the study were identified and dealt with accordingly, resulting in a final sample of one-hundred-and-fifty-three [153] inmates for cognitive analyses with no change to the primary sample (where extremities were not excluded but modified).


For the criminal history analysis, the ASPD-only, ASPD+PSY and control groups were evaluated based on three distinctions of criminal behavior: violent crime (murder, sexual assault, armed robbery), nonviolent crime (theft, forgery, arson), and criminal versatility (the variety of offences the inmates were charged with). The Independent variable (IV) in this case would be the grouping of inmates based on their disorders, and the Dependent variable (DV) would be their corresponding criminal charges.

The global-local processing task was utilized for the measurement of cognitive processing. This task is designed in such a way that the frequency of presented stimuli on global or local levels could be varied to differentially activate the relevant hemisphere-specific perceptual system. Each participant was provided a computer which displayed stimuli in the form of alphabet letters on the screen; specifically the target stimulus (S or H) presented on a local or global level, and a distraction stimulus (A or E) at the opposite level. Each stimulus was presented for a duration of one-hundred-and-fifty [150] milliseconds and participants responded by pressing the corresponding key (S or H) on the keyboard. Target frequency, the Independent Variable (IV), was fluctuated to manipulate LH versus RH processing while response latency and accuracy of the inmates, the Dependent Variable (DV), was calculated. Under Local Bias conditions (L) the targets had an appearance rate of 80% at the local level and 20% at the global level. The opposite occurred in Global Bias conditions (G). In the Neutral condition (N), the target had chance to appear equally as often at either global or local levels. Participants completed eight [8] practice runs and sixty-four [64] trials per condition.


A variety of statistical tests were utilized throughout the current study. Chi-square (X2) distribution was used to show that no relationship existed between ethnicity and group membership, and Welch F’ and t’ tests were used to demonstrate that demographic variables such as IQ, and age were not associated with any indices of criminal behavior or cognitive processing in any condition. Analyses of variance (ANOVAs) and complement t’ tests were the primary means of comparing groups on both the criminal behavior and cognitive processing portions. Cohen’s measure of effect size was used throughout to measure the impacts of the IV in both portions of the study. All the obtained results had very low p values, suggesting that they were not due to simple chance.

Primary analyses of criminal behavior expressed that both ASPD-only and ASPD+PSY groups were charged with more violent, more nonviolent, and more types of criminal offences than control groups with a relatively small effect size. Furthermore, ASPD+PSY inmates showed more severity on all three distinctions of measured criminal conduct compared to ASPD-only inmates with small to medium effects. Additionally, the above analyses was repeated but this time involving a much more stringent criteria to diagnose ASPD (5 of 7 symptoms or 71.4%) to make it more comparable to the strict selection criteria for psychopathy (PCL-R score of 30/40 or 75%). The new analyses which involved the updated ‘severe’ ASPD inmates did not bring about any significant change to the results.

Primary analyses of cognitive processing illustrated that, for local targets in local bias conditions, the response latencies of ASPD+PSY inmates were greater than both control and ASPD-only inmates to a large effect. However, the ASPD-only group did not differ from the control. The groups also differed in response latencies for global targets in local bias conditions with ASPD+PSY inmates responding more slowly than the ASPD-only group, but not slower than the control group (to a small effect). There were no significant group differences in response latencies for local or global targets under both neutral and global bias conditions.


Dear Dr. Neo Cortex

Over the course of writing this paper, I have learnt quite a few things about these two particular personality disorders. Rarely have the relationships between ASPD and psychopathy been explored within the same study, so this particular research provides plenty of new evidence and perspectives into the nature of both syndromes. I would like to discuss with you the end results of the study, which of the observed hypotheses are substantiated, and the implications it might have.

Both before and after the stringent criteria was utilized to re-diagnose ASPD, inmates with ASPD with comorbid psychopathy averaged more violent charges and a greater variety of charges than ASPD only inmates. From this, it can be inferred that criminal behavior does not indeed correlate to the severity of the criteria used to diagnose psychopathy. This invalidates the co-primary hypothesis H2 that psychopathy is merely a severe form of ASPD.

Also, the results from the cognitive processing analyses are inconsistent with the null hypothesis H0 which states that ASPD with and without comorbid psychopathy are disorders that reflect the same underlying mechanism. Under local bias conditions (L), the ASPD+PSY group demonstrated poor response latencies in accordance to LHA hypothesis. However, not only did the ASPD-only group not show similar deficits in cognitive processing, they performed on par with the controls and even better than the ASPD+PSY group in responding to global and local targets under local bias conditions (L). This demonstrates that individuals with psychopathy may host a neurocognitive defect that is not shared by those with antisocial personality disorder only.

These results obtained from both the criminal behavior and cognitive processing analyses provide validation for the primary hypothesis H1, that ASPD with and without comorbid psychopathy are not two syndromes which reflect the same underlying pathophysiology but are disorders characterized by distinct mechanisms. The implications of this study are worthy of note, as such findings are inconsistent with the personality disorder revisions in Section II of DSM –V, which continues to categorize psychopathy and ASPD as a singular diagnosis. This would undoubtedly lead to a reduction of diagnostic specificity, especially since this and other studies have (somewhat) established that ASPD with and without comorbid psychopathy are different on the neural, cognitive, and emotional levels.

Having said that, this study is not in any way without its flaws and limitations, despite the numerous precautions taken by the researchers. The biggest limitation that I find in this study is that it is restricted within a male population. The study could have greatly benefited from including female participants, or have held separate analyses for women. I assume that females with ASPD and psychopathy would behave in ways different enough (due to social roles, etc.) to warrant study. Understandably, this first limitation is a direct result of the next one; the sample was restricted to one country jail in Illinois. A felony conviction is required for a sentence into such state prisons, making the sample less representative of criminal offenders as a whole (as most convicts with nonviolent or minor offences don’t get sent to maximum security prisons). Also, Illinois is hardly representative of the entire United States, so studies that set out to replicate this one should look into collecting samples from correctional facilities across state lines. This sort of study would also be aided if samples (mostly control groups) are obtained from outside of correctional settings. Finding nonclinical participants could help set baseline readings with regards to criminal behavior and cognitive processing.

I would also suggest that future studies try to test other variables between ASPD and psychopathy, such as the level of self-esteem, age of onset of criminal behavior, or perhaps something physiological such as structural differences in the brain. I believe that this is just the beginning of research into this topic and would like to see where researchers such as yourself would take the field with the information you have today.

Best of luck on your next scheme to rule the world


American Psychiatric Association. (2006). Diagnostic and statistical manual of mental disorder: Test revisions (4th ed.). Washington, DC.

Kosson, D. S., Lorenz, A. R., & Newman, J. P. (2006, November). Effects of comorbid psychopathy on criminal offending and emotion processing in male offenders with antisocial personality disorder. Journal of Abnormal Psychology, 115(4), 798-806. doi:10.1037/0021-843X.115.4.798

Llanes, S., & Kosson, D. S. (2006). Divided visual attention and left hemisphere activation among psychopathic and non-psychopathic offenders. Journal of Psychopathology and Behavioral Assessment, 28, 9-18. doi:10.1007/s10862-006-4533-2

Riser, R. E., & Kosson, D. S. (2013). Criminal behavior and cognitive processing in male offenders with antisocial personality disorder with and without comorbid psychopathy. Personality Disorders:Theory, Research, and Treatment, 4(4), 332-340. doi:10.1037/a0033303

Serin, R. C. (1991). Psychopathy and violence in criminals. Journal of Interpersonal Violence, 6, 423-431. doi:10.1177/0886260910060040021991

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