Gray matter correlates of impulsivity in psychopathy and in the general population differ by kind, not by degree: a comparison of systematic reviews

Abstract

A fundamental question in neuropsychiatry is whether a neurobiological continuum accompanies the behavioral continuum between subclinical and clinical traits. Impulsivity is a trait that varies in the general population and manifests severely in disorders like psychopathy. Is the neural profile of severe impulsivity in psychopathy an extreme but continuous manifestation of that associated with impulsivity in the general population (different by degree)? Or is it discontinuous and unique (different by kind)? Here, we compare systematic reviews of the relationship between impulsivity and gray matter in psychopathy and in the general population. The findings suggest that the neural profile associated with extreme impulsivity in psychopathy (increased gray matter in rostral and ventral striatum and prefrontal cortex) is distinct from that associated with impulsivity in the general population (decreased gray matter in rostral and ventral prefrontal cortex). Severe impulsivity in psychopathy may therefore arise from a pathophysiological mechanism that is unique to the disorder. These findings prompt the need for future studies to directly test the effect of group on the impulsivity-gray matter relationship in samples comprised of healthy individuals and individuals with psychopathy. The results caution against the use of community samples to examine impulsive psychopathic traits in relation to neurobiology.

A multidimensional examination of psychopathy traits and gray matter volume in adults

“…OFC, insula) ( Leutgeb et al. , 2015 ; Korponay and Koenigs, 2021 ). However, the majority of the studies presented in the psychopathy literature contain predominantly male samples and often contrast psychopathic with non-psychopathic individuals ( Koenigs et al.…”

“…, 2012 ; Leutgeb et al. , 2015 ; Korponay and Koenigs, 2021 ). We also expected that the interactive effects of the psychopathy factors would parallel the neurobiological abnormalities observed for individuals high on psychopathy.…”

“…the striatum) ( Cope et al. , 2012 ; Korponay and Koenigs, 2021 ) and negative associations between F2 traits and the middle occipital gyrus ( De Brito et al. , 2021 ) and the supplementary motor area ( Leutgeb et al.…”

“…There have also been F2 trait associations with GMV in the prefrontal cortex, although the findings have been mixed, with some studies reporting positive GMV associations in the prefrontal cortex ( Korponay et al. , 2017 ; Korponay and Koenigs, 2021 ) and others reporting negative associations ( De Brito et al. , 2021 ), including with the OFC.…”

“…, 2021 ), including with the OFC. It is possible that these observed discrepancies could be due to the types of populations being studied, as recent research has pointed out that the neural mechanisms underlying impulsive traits may differ in forensic v s community samples ( Korponay and Koenigs, 2021 ). In spite of these possible specific GMV associations with the psychopathic trait dimensions, it should also be noted that distinct associations are not always observed, as evidenced by studies showing both psychopathy factors are negatively associated with GMV in the orbitofrontal cortex ( Ermer et al.…”