Edited by: Cristina Scarpazza, Università degli Studi di Padova, Italy
Reviewed by: Carlo Garofalo, Tilburg University, Netherlands; Inti Brazil, Radboud University Nijmegen, Netherlands
This article was submitted to Forensic Psychiatry, a section of the journal Frontiers in Psychiatry
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Executive functions (EFs) are essential in almost all aspects of daily life and have been robustly related to antisocial behavior. However, the relationship between psychopathy and EFs has remained equivocal. Research investigating lower-level trait dimensions of psychopathy using standardized EF measures could be beneficial in addressing this issue. In this study, we examined associations between four EFs and four dimensions of psychopathic traits (interpersonal, affective, lifestyle, antisocial) using zero-order correlation and a combination of classical and Bayesian statistical methods. Two hundred and fourteen incarcerated male violent offenders were assessed with the Psychopathy Checklist-Revised and completed tests of cognitive flexibility, spatial working memory, response inhibition, and planning and problem-solving using the Cambridge Neuropsychological Test Automated Battery. Lifestyle psychopathic traits were significantly associated with reduced initial thinking time in a planning and problem-solving task, with a Bayes factor indicating substantial evidence for the observed correlation, and antisocial psychopathic traits showed a significant association with reduced initial thinking time in the same task, although the Bayes factor indicated only anecdotal evidence. Significant associations were also found between affective and antisocial psychopathic traits and less efficient strategic thinking in a spatial working memory task, and between affective, lifestyle and antisocial psychopathic traits and fewer problems solved in a planning and problem-solving task, although these findings were not corroborated by the Bayesian analysis. While the observed effects ranged between small and medium, our study suggests that reduced initial thinking times in planning and problem-solving is robustly associated with higher degrees of lifestyle and antisocial psychopathic traits.
Executive functions (EFs) are essential in almost all aspects of daily life. Described as a set of separate but related top-down cognitive processes that come into play whenever automatic behaviors are insufficient or inappropriate, EFs govern self-regulated and goal-directed behavior. It is generally agreed that there are three core EFs—cognitive flexibility, working memory, and inhibition—from which higher order EFs such as planning and problem-solving are built (
The pattern of inconclusive results may perhaps primarily be attributed to two issues. First, EFs have been measured differently across studies, possibly due to the broad nature of EFs making exact definition and operationalization inherently difficult [e.g., (
Common operationalizations of psychopathy can be seen in the use of measures such as the Self-Report Psychopathy scale, currently at its fourth edition [SRP-4; (
To summarize, EFs have been associated with a wide range of antisocial behaviors, including disadvantageous treatment engagement and recidivism. As mentioned, offenders with a high degree of psychopathic traits display higher rates of violence, are more prone to recidivism, and more resistant to treatment than offenders with low levels of psychopathic traits, yet the role of EFs in relation to psychopathic traits remains uncertain. To address these issues, the present study investigated associations between psychopathic traits and four different EFs in a clinically well-described sample of incarcerated male violent offenders. More specifically, using open statistical analysis (
Participants (
Psychopathic traits were measured using the PCL-R (
Four subtests of the Cambridge Neuropsychological Test Automated Battery (CANTAB; Cambridge Cognition Ltd., Cambridge, UK) were used to assess EFs: Intra/Extra Dimensional Shift (IED), Spatial Working Memory (SWM), Stop-Signal Task (SST), and Stockings of Cambridge (SOC). The choice of CANTAB and the subtests included in the current study were due to the primary focus on neurodevelopmental disorders (e.g., ADHD) in the DAABS study. CANTAB has been used extensively and successfully in studies on ADHD [see e.g., (
The IED, similar to the Wisconsin Card Sorting Test (
The SWM is a self-ordered searching task assessing spatial working memory ability. Participants search for tokens hidden inside boxes, with the number of boxes gradually increasing from two to eight as the task progresses. Measures used in the current study were number of errors and strategy score. The strategy score, ranging from 0 to 40, is a measure of optimal strategy (
The SST was used to assess response inhibition (
The SOC is a computerized version of the Tower of London task (
Data preparation and statistical analysis was conducted using R (
This study was approved by the Research Ethics committee at Lund University (Dnr: 2009/405). All offenders fulfilling inclusion criteria were approached by study site managers and received oral and written information about the study in accordance with the Declaration of Helsinki. All participants in the study gave written informed consent. A compensation of 200 Swedish kronor (approximately 20 USD) was given after participation. The compensation was small enough to not create an incentive that would compromise the free ground for participating in the study and was approved by the ethics committee. Participants who showed signs of severe psychopathology were given the opportunity to be referred to the prison psychiatrist for further assessment and treatment whenever there was such an option.
An overview of PCL-R facet scores and performance on EF measures is presented in Table
Descriptive statistics (
PCL-R interpersonal facet score | 0.9 ± 1.34 | 0–8 |
PCL-R affective facet score | 3.15 ± 2.26 | 0–8 |
PCL-R lifestyle facet score | 6.45 ± 2.61 | 0–10 |
PCL-R antisocial facet score | 6.3 ± 2.88 | 0–10 |
IED stages completed | 8.1 ± 1.13 | 1–9 |
IED errors | 26.7 ± 12.5 | 7–63 |
SWM errors | 23.14 ± 17.24 | 0–90 |
SWM strategy score | 32.47 ± 5.12 | 0–47 |
SST stop-signal RT | 0.19 ± 0.08 | 0.07–0.74 |
SST mean correct RT | 0.48 ± 0.14 | 0.3–1.27 |
SOC MITT | 6.03 ± 4.78 | 0–29.38 |
SOC problems solved | 8.3 ± 1.75 | 4–12 |
Lifestyle psychopathic traits were significantly and negatively associated with a lower mean initial thinking time (Figures
The present study investigated associations between four different EFs (cognitive flexibility, working memory, inhibition, planning, and problem-solving ability) and four different psychopathic traits (interpersonal, affective, lifestyle, antisocial) using zero-order correlations and a combination of classical and Bayesian statistical methods in a well-described, nationally representative cohort of young Swedish male violent offenders. Although several significant associations were observed, the subsequent Bayesian analysis indicated evidence in favor only of associations between antisocial and lifestyle psychopathic traits and lower mean initial thinking time in the SOC task. Overall, the observed effects ranged from small to medium (
We suggest that the association between lower mean initial thinking time and higher degrees of lifestyle and antisocial psychopathic traits could be interpreted as an impulsive approach to planning and problem-solving. Previously, (
Directions for future research may be further uncovered by focusing on the underlying mechanisms of planning and problem-solving. It appears that while planning and problem-solving is a complex task engaging a wide range of neural regions, the dorsolateral prefrontal cortex (DLPFC) is most robustly activated (
Another region implicated in psychopathy (
Interestingly, one aspect of spatial working memory—less efficient strategic thinking—has also been interpreted as reflecting impairments in planning and problem-solving (
Finally, at least one previous study has found that increased interpersonal psychopathic traits were related to committing fewer errors in a working memory task (
We could not replicate the many previous findings of deficit response inhibition related to impulsive and antisocial psychopathic traits (
No significant associations between psychopathic traits and measures of cognitive flexibility were found in the current study. Impairments in cognitive flexibility has been observed in both violent and non-violent offenders (
Finally, we must mention our choice of EFs and how they were assessed. The EFs that were available in this study may be described as primarily “cool” EFs, meaning they have little emotional or contextual input. In contrast, so-called “hot” EFs involve components of motivation and affect and are more sensitive to ventromedial prefrontal cortex (vmPFC), OFC, and amygdala function than cool EFs (
The study has some notable strengths in the large, nationally representative sample of incarcerated young violent offenders, the combination of classical and Bayesian statistical methods used, the open science practices followed, the trait-level approach to psychopathy, and the inclusion of several EF measures. The study also has several limitations that must be mentioned. The choice of EF tasks, while in line with previous literature, were selected due to the focus on neurodevelopmental disorders, and not primarily psychopathy, in the DAABS study. We also opted for an approach where the effects of each EF were investigated separately instead of using a global EF measure, which might have rendered more statistical power. Still, using a global EF makes it difficult to disentangle possible separate effects of different EFs. Another limitation is the high attrition rate in the SST task, which might have affected our results. We chose to omit participants rather than imputing the data, since we suspected non-random attrition. It should also be noted that participants scored relatively low on the interpersonal facet, compared to previous studies (
In summary, we report findings from a well-described, large and nationally representative sample of incarcerated young violent male offenders. Our results suggest that reduced initial thinking time in planning and problem-solving may be important cognitive markers for impulsive and antisocial psychopathic traits. We also tentatively propose that impairments in the left DLPFC and the OFC might be the neurobiological underpinnings of these observations. The results from this study are in line with some previous research suggesting that that specific EFs are related to specific psychopathic traits, albeit to varying degrees with small to medium effect sizes. Several discrepancies still remain, and further research is necessary. We recommend that future studies incorporate planning and problem-solving tasks in conjunction with functional neuroimaging techniques to further delineate the relationship between planning and problem-solving, DLPFC and OFC activity, and psychopathic traits. Overall, continued research would benefit from including several measures of the same EF, and also from including hot EFs.
CD, MW, and BH conceived and designed the study. EB, MW, and BH obtained the data. CD drafted the initial manuscript with contributions from PA and MW. CD did all the analyses. Finally, all the authors critically revised the manuscript and approved the final version.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We gratefully acknowledge Lennart Palmgren and Svenolov Svensson for their generous support of the study, all site managers for their hard work during the assessments, Therese Olsson, Viveca Spong, Natalia Theander, and Mattias Filipazzi for indispensable help during data collection, Monika Montell, Jan Wikdahl, and Stefan Axelsson for their help with the database, and Henrik Anckarsäter for excellent advice in designing the DAABs study. Finally, we would like to express our gratitude to all prisoners for their participation.