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

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 cortexes) is distinct from that associated with impulsivity in the general population (decreased gray matter in rostral and ventral prefrontal cortexes). 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.

神经精神医学中的一个基本问题是，在亚临床特征和临床特征之间的行为连续体是否伴随着神经生物学的连续体。冲动性是一种在普通人群中存在差异的特质，在精神病态等疾病中表现得很严重。精神病态中严重冲动性的神经特征是普通人群中与冲动性相关特征的一种极端但连续的表现（程度上的差异）吗？还是不连续且独特的（性质上的差异）呢？在这里，我们比较了关于精神病态和普通人群中冲动性与灰质之间关系的系统综述。研究结果表明，与精神病态中极端冲动性相关的神经特征（吻侧和腹侧纹状体以及前额叶皮质的灰质增加）不同于普通人群中与冲动性相关的神经特征（吻侧和腹侧前额叶皮质的灰质减少）。因此，精神病态中的严重冲动性可能源于该疾病特有的病理生理机制。这些发现促使未来的研究需要在由健康个体和精神病态个体组成的样本中直接测试群体对冲动性 - 灰质关系的影响。研究结果提醒不要使用社区样本研究与神经生物学相关的冲动性精神病态特征。