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This meta-analysis investigated the relationship between measures of brain imaging and psychopathy. The study population included a total of 58 studies in which measures of aMRI, fMRI, SPECT, and PET from patients with diagnosed psychopathy were compared to those obtained from control populations. The typical hypothesis in these studies was that those patients with psychopathy would show deficiencies in neural activity and brain matter in the prefrontal cortex relative to controls. The meta-analysis results indicated an overall significant effect size across studies of approximately 20%. The effect size was consistent across 56 of the 58 studies. Two studies showed an effect that was not in the predicted direction. Effect size was also related to the type of brain imaging. Those studies that used fMRI and MRI techniques produced generally smaller effect sizes relative to those that used aMRI, PET or SPECT techniques. The effect sizes in these studies were unrelated to other variables, such as the sample size, percent of males in the study, and the average age of the participants. The results demonstrate abnormal activity in the PFC regions of people with psychopathy when compared to controls.
Yang and Raine (2009) provided a meta-analytic evaluation of 43 studies, dating from 1994 through 2007, involving brain imaging in antisocial, violent and psychopathic individuals. These studies reported significant impairments in the prefrontal cortex of antisocial individuals; specifically, impairments were shown in the right orbitofrontal cortex, right anterior cingulate cortex, and left dorsolateral prefrontal cortex. The purpose of this meta-analysis was to evaluate recent studies (2009- present) that assessed differences in functional imaging variables in the prefrontal cortex and their relationship to antisocial or psychopathic behavior.
Why is it important to study the relationship between brain physiology and psychopathy? First, it is necessary to find the cause of psychopathy in order to understand, diagnose, and formulate a program of treatment for these individuals. Second, the burgeoning field of brain imaging technology provides a more expansive look into the human brain in search of a biological basis for psychopathy. Third, the implications of these studies could advance the understanding of other related neuropsychiatric conditions such as sociopathic behavior, bipolar conditions, or aggressive tendency. Finally, it may be argued that, much like those with severe mental disabilities, the...