A Research on Child Psychopathy and Brain Imaging

Introduction

Psychopathy is one of the most complex disorders to spot in an individual. Diagnosis can begin in early youth. Children are first noted to have psychopathic traits or tendencies. These traits often overlap with Conduct Disorder and Oppositional Defiant Disorder. Psychopathic traits are, typically, detected in early childhood when personality begins to develop and continue into adulthood (Marsh, et al., 2013). The traits referred to as psychopathic are lack of empathy, grandiose sense of self-importance, impulsiveness, and anti-social behavior. Psychopathy is mostly diagnosed by an interview checklist assessment, Psychopathy Checklist-Revised, which was created by Robert Hare. However, neuroimaging in relation to psychopathy is developing a strong background of research and support to offer another form of diagnosis. Brain imaging of psychopathic individuals has shown significant relations between psychopathy and brain structure, particularly the amygdala and prefrontal cortex. White matter and grey matter concentrations, emotional and facial recognition tasks, surface areas of the brain, and functional impairments have also been researched using neuroimaging in the psychopathic field. The literature on these topics is substantial in quantity and is often in line with Hare’s diagnosis theory and checklist as well.

Different Types of Brain Imaging

There are three main types of brain imaging technology. The first is an electroencephalogram (EEG) which tracks the activity of brain waves. EEG has been researched and used to show both attention and motor control areas in the brain, which makes it very useful when trying to understand how psychopaths may process certain tasks. The next is the most common form of imaging is called magnetic resonance imaging (MRI) which uses magnetic pulses and movements to take images of structures. Research studies using MRI have found that brain structure and volume may help in understanding the different levels of psychopathy. Branching from an MRI, the last technique is functional magnetic resonance imaging (fMRI) which shows blood flow or activity in the brain. Functional MRI studies have linked abnormal emotional processing and decision making to the insula of the brain.

Findings from Brain Imaging Research

The brain of psychopathic individuals, from a visual and anatomical standpoint acquired from MRI’s, does not appear to have any abnormalities on the surface (Pujol, Harrison, Contreras-Rodriguez, & Cardoner, 2018). Whole brain volume is typically reported normal as well except in very few cases. It has been reported in some studies, however, that there is a high volume reported in psychopathic individuals in the prefrontal lobe and somatosensory cortex. Reduced volume of the amygdala has also been reported. The amygdala plays a primary role in facilitating empathy for another person. Impaired structure and functioning of the amygdala keep an individual from associating their actions with the distress of others. It has been concluded from several fMRI studies that reduced amygdala volume and activity is associated with the processing of emotional stimuli. In another study, reduced amygdala responses appeared to be the reason the psychopaths studied showed lack of response increase other’s pain, but not their own pain. Lack of attachment and interpersonal deviancy have also revealed as a link to reduced amygdala volume. A part of the brain called the insula, which is not limited to a certain function, has also been linked to psychopathy. Insula volume and the trait of boldness in over 30 individuals showed a positive correlation (Vieira, et al., 2015). The study found that increased insula volume led to increased boldness in a person. The researchers suggested from their imaging findings that decreased insula volume could be the reason for anxiety in other cases.

Grey matter of the brain is another area of concern in neuroimaging studies of psychopathy. Grey matter includes parts of the brain that are involved in muscle control, sensory perception, decision making, and self-control. White matter connects areas of grey matter together. White matter is composed of neural fibers, or axons, that are covered by myelin. It has been found in youth with psychopathic tendencies, particularly boys with conduct disorder and callous-unemotional traits, that there is a decreased white matter concentration compared to typically developing children (Brito, et al., 2010). However, although there is a white matter decrease reported for these individuals, there has also been a grey matter increase found in contrast. Using MRI screening, a study found that most of the white matter abnormalities were found in the front temporal lobe. It was also discovered that the typically developing boys had results that showed white matter concentration increase as expected with age, whereas, the boys with psychopathic tendencies showed a decrease. Decreases in grey matter concentration are substantially consistent in findings of most brain imaging studies on psychopathic individuals, especially in the frontal and temporal lobes. White matter concentration increase was reported in various studies as found in the corpus callosum and prefrontal area. Recent MRI reports correspond with the idea that white matter increases are results of significant accelerated myelination. Diffusion tensor imaging (DTI) is a rarely used neuroimaging technique that allows for the estimation of location and orientation of white matter. Alterations of white matter pathways in the frontal lobe have been found from DTI data (Pujol, Harrison, Contreras-Rodriguez, & Cardoner, 2018). Psychopaths imaging have found that higher grey matter concentration in the prefrontal and cortical areas led to better facial emotional expressions. It has been noted in some studies that patterns of white matter abnormalities in youths have not been found consistent as some have shown increase in one area, but a decrease in another.

Facial recognition tasks are often evaluated among psychopathic individuals when measuring grey and white matter volumes with the intentions of discovering a relationship between the two using neuroimaging techniques. Voxel-Based Morphometry is technique using MRI that is often used to observe this relationship. Using this technique, a facial expression is often morphed, and psychopathic individuals are asked to recognize positive and negative emotions. In one study in particular, psychopathic male offenders showed deficits in the recognition of sad, happy, and fear emotional expressions. It has been found that psychopaths with better recognition of facial expressions had a higher grey matter volume in the prefrontal area. Altered neural processing of emotional stimuli in psychopaths is indicated by many studies. However, a psychopath’s brain is not necessarily entirely unemotional. Enhanced brain response has been reported in MRI results for visual sensory areas which suggests that there is a disruption of emotional flow. Functional MRI studies have found the possibility of poor temporal lobe transmission emotional flow to the frontal system. Psychopaths have shown reduced activation in the prefrontal cortex, when viewing facial expressions or violence (Umbach, Berryessa, & Raine, 2015). Youths studied with psychopathic traits showed reduced amygdala responses to fearful facial recognition tasks.

Recent EEG studies have suggested that there is an inverse relationship between overallocation of attentional cues and reduced resources for motor control in psychopathy. Alpha particle activities in the brain are examined by an EEG which is often done so while the individual is asked to complete a certain motor task (Tillem, Brennan, Wu, Mayes, & Baskin-Sommers, 2018). These findings provide evidence for attentional issues in psychopathic individuals.

Cortical thickness and surface area of the brain have been contributed to psychopathy as well. Around ages 8-9 years old, both cortical thickness and surface areas are supposed to be at their developmental peak. One study reported that children with callous-unemotional traits when compared to typically developing children showed reduced thickness and surface area (Fairchild, et al., 2015). Increased insula folding has been found as well in comparison with healthy controls. Although, it has been found that there is inconsistency in fMRI measures regarding cortical dimensions of the insula. Reduced cortical thickness in the prefrontal cortex was found in a population of children diagnosed with conduct disorder and psychopathic tendencies. This led to the association of tendencies such as aggression or moral judgement could be directly related to cortical volume (Sarkar, et al., 2014). However, very few studies show both reduced cortical thickness and surface area from MRI research. Cortical thickness seems to be consistent with many studies that have found reduced thickness or cortical “thinning” in the prefrontal cortex (Wallace, et al., 2014). These results were reported to remain consistent in smaller groups during more extensive fMRI screening.

Brain function has been studied mainly by examining overall anatomy of the whole brain using MRI screening. The amygdala is the main area of concern according to psychologists and researchers in regard to brain function of psychopaths. Within certain samples, an association has been made between the persistence of the cavum septum pellucidum, a fluid-filled space in the septum, and higher psychopathy scores. It has been found that the cavum has been prevalent in other behavior disorders as well, which suggests it could be a generalized finding and not specific to psychopathy. Functional connectivity is the activity of between brain regions sharing information with one another. Reduced functional connectivity has been reported in the frontal cortex from MRI data on psychopathic individuals. The consistent research findings of impaired amygdala and frontal cortex function allow most researchers to assume that psychopaths have a dysfunctional emotional-limbic system. Neuroimaging studies have revealed that the amygdala is responsible for a variety of emotions, not just one. It has been suggested by a group of researchers that the source of amygdala impairment occurs early in childhood development (Glenn & Raine, 2008). Asymmetric abnormalities in the hippocampus have been found in unsuccessful psychopaths as well. Raine et al. suggested that hippocampus dysfunctions may be the reasoning for insensitivity and dysregulation in psychopaths. Striatal alterations have been reported for psychopaths as well, which would be related to reward processing and decision-making dysfunction. The insula has been studied to reveal increased volume when examining boldness and has been previously implicated in defensive networks. The connectivity of the insula during threatened situations is reliant of anxiety.

Limitations of Brain Imaging and Psychopathy Research

Although neuroimaging has a lot to contribute to psychopathy research, it can only take us so far in understanding the disorder. Voxel-Based Morphometry (VBM) has revealed information regarding structure of cortical areas, however, VBM cannot reveal the nature of these facts. For example, it limits the explanation of why changes in volume or structure occur. Most studies on psychopathic children do not include sex-based differences. This is mainly due to the already small population of psychopathic individuals in a study. It is already difficult to find certain ages and ethnicities much less account for sex differences. This goes hand-in-hand with another common limitation of neuroimaging research which is a small sampled size. Most of the studies mentioned in this review are between 15-40 individuals for a sample size. Although it allows extensive review of the individuals who were studied, it does not allow for reliability. Larger sample sizes could reveal more brain and behavioral function relationships that the smaller samples do not. Regarding MRI scanning, limitations include the type of MRI machine. Different types of machines could yield different results in regard to volume and structure. Another limitation regarding MRI’s is the type of head coils which are used. Different head coils are used based on the head size of the individual. It was also suggested in one study that limitations occur from the MRI site that the individual goes to get the screening done. The staff at the site could potentially influence the participants in one way or another.

Conclusion

It is obvious that neuroimaging brings a lot of knowledge to the field of psychology. The many techniques of brain imaging allow for research and analysis of almost any brain function. This allows for the understanding of how the brain function during different emotions and tasks. Brain imaging has revealed that the structures of the amygdala and prefrontal cortex are linked to psychopathy; without the use of MRI scans, this information may not be as reliable and valid as it is today. Concentrations of grey and white matter are also brought to the table as a possible explanation for psychopathy disorder due to fMRI studies and research. It has also been revealed by various MRI and EEG studies that psychopaths due in fact have emotions, there is just a disconnect on how they process emotions. This information alone can help psychologists by developing better treatment plans and therapies for psychopaths. Mainly MRI and fMRI scans have opened the door for a possible new one to diagnosis or confirm the disorder of psychopathy. Overall, brain imaging has brought the understanding how the brain of psychopaths’ process and connect information, which is imperative to provide both diagnosis and treatment options.

References

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