Biological Basis of Psychopathy and Altruism
Origins of Social and Antisocial Behavior
Psychopathy is a personality disorder believed to be affecting 1-2% of the world’s population. Those afflicted have certain personality characteristics: Shallow emotions, superficial charm, impulsiveness, and lacking any empathy or remorse, often leading to antisocial behaviors and criminal activity. The general consensus among psychologists is that most people fall towards the center of a continuum of personality traits, with the extreme cases on opposite ends. Considering one extreme to be those psychopathic traits, the other extreme, some may argue, would consist of traits relating to an altruist, someone with a sincere, unselfish concern for others.
This post will review the methods, and compare the findings of two studies: “The Neural Signatures of Distinct Psychopathic Traits”, which explores the relationship of brain structure and function with self-reported psychopathic traits, as well as “Neural and Cognitive Characteristics of Extraordinary Altruists”, which explores the structural and functional differences of the typical brain to that of extraordinary altruists, defined in the study as: An altruistic kidney donor who volunteered to donate a kidney to a stranger.
Researchers Carre, Hyde, Neumann, Viding, and Hariri randomly chose 200 young adult, student volunteers consisting of 117 women and 83 men, from a pool of participants in a more large-scale study, the Duke Neurogenetics Study. Those who were taking certain medications or had certain medical conditions were excluded. Once selected, participants were first asked to complete the Self-Report Psychopathy-Short form (SRP-SF), which has been shown to be an accurate measure of psychopathy.
While scanning each participant with a General Electric MR750 3T scanner (fMRI), participants were then instructed to do a series of face-matching and sensorimotor tasks. The face-matching task consisted of facial expressions for one section of each: fearful, angry, surprised, and neutral expressions. The participants had to pick out of a group of faces, located on the bottom of a screen, with the exact match of a face at the top of the screen. The sensorimotor tasks were inserted randomly in between the face-matching tasks; Participants had to match the identical shape out of a key of options at the bottom of the screen, with the shape at the top of the screen. Only data from the fearful and angry face-matching tasks were later used for analysis.
Next, participants played a series of trials of a card guessing game, and were given either positive or negative feedback for each trial. For one out of every five trials, the participant was given incorrect feedback, even if they correctly answered. Participants were told that their performance on these tasks would determine the amount of money they will receive as a reward at the end of the game. The purpose of this portion of the experiment was to analyze activation of the participant’s ventral striatum, which includes the nucleus accumbens, and the ventromedial regions of both the caudate and putamen. These structures are all involved in processing motivation due to stimuli in the environment, controlling appetitive behaviors, and forming ideas of reward expectancy and prediction.
Data was organized and then used to determine any significant relationships between the self-reported psychopathic traits, with amygdala and ventral striatum task-specific activation. The ventral and dorsal amygdalae were analyzed separately, as one region’s function is for input, and the other for output.
Considering the majority of research on psychopathic individuals was done on men, the researchers looked for any differences in results due to gender. Three relationships were determined to be significant. Researchers found that there was higher activation to fearful faces in the right dorsal amygdala in men compared to women. Also, the lifestyle aspect of psychopathic traits was associated with more right amygdala reactivity to anger in men, and the affective aspect was associated with higher right ventral striatum activation in women.
Additionally, it was found that the higher someone scored on the interpersonal aspect of psychopathy, the less activation there was in both the ventral and dorsal amygdala in response to fearful faces. Further, there was a significant association between a high score on the lifestyle aspect of psychopathy with both low activation of the ventral striatum in response to positive feedback, and high activation of the amygdala due to angry faces. The latter was seen by the researchers to contrast with past studies suggesting psychopathy to be exclusively associated with under reactivity of the amygdala.
In response to the growing amount of data on psychopaths’ structural and functional brain abnormalities, Marsh et al. devised a study with the focus on individuals at the other end of the spectrum. In “Neural and Cognitive Characteristics of Extraordinary Altruists”, the researchers believe these altruistic individuals, defined as an altruistic kidney donor who volunteered to donate a kidney to a stranger, to be the inverse of psychopathy and so set out to test this hypothesis. Researchers recruited, with the help of mailings and electronic advertisements and a cash incentive, thirty-nine adults, all with ages between twenty-three and fifty-six. Participants included: nineteen altruistic kidney donors, sixteen who did not know who would receive the donation until after the procedure, and three that knew who would receive the kidney at the time of donation, but did not personally know them before finding out they needed a kidney.
All interested in volunteering as a control for the study first completed an online screening survey. Those who were accepted through the preliminary screening then had to go to the laboratory and answer a series of questions to determine if there were any reasons for exclusion: anyone reported to have donated an organ, the use of psychotropic medication at the time of the study, history of any head or neurological illnesses, pregnancy, any conditions that would make it unsafe to be involved in MRI scanning, or anyone with an IQ less than 80; determined with the use of the Kaufman Brief Intelligence Test-Second Edition.
Participants were then instructed to complete an implicit face-processing task while simultaneously being scanned with a 3T Siemens Tim Trio Scanner (fMRI). Ten images of both male and female adults, all with their necks, ears, and hair blocked from view, were shown to the participants. Fearful, angry, or positive-neutral expressions were shown in a randomized order. The participants were told to categorize the sex of each face throughout the task; therefore they did not know the importance of the emotional part of the task. Along with the response, the response times for each portion were also recorded.
Participants then had to do a facial emotion recognition task. Pictures of faces expressing basic emotions were shown: anger, disgust, fear, happiness, sadness, and surprise. The participants then had to make a choice as to what emotion the face was expressing. There was no time limit for this part of the study. Data from this portion of the study was organized measuring both raw and differential accuracy. Raw accuracy is how often an emotional expression was shown divided by how often the participant correctly answered. Differential accuracy is how often the participant correctly chose a response compared to the amount of time the same response was given. Instructions were then given to complete two self-report tests the PPI-R, used to measure psychopathic personality traits and the IRI, used to measure empathic abilities in an individual. One last test was given before data analysis; Participants had to complete the Reading the Mind in the Eyes test to assess the extent that someone can understand or relate to another individual’s mental state of mind.
Neutral faces were used as a baseline, and focus was placed on left and right amygdalae when comparing responses. FreeSurfer image-analysis suite, a program that uses MRI data to process structural images in the brain, was used to map out 112 different areas of the brain for each participant. Data was then categorized into white matter, gray matter, or cerebral spinal fluid. It was found that altruists’ intracranial volume was an average of 9.1% higher than controls’. Right amygdala volume was also found to be an average of 8.1% higher in altruists, although there was no correlation found between the size of the amygdala and scores for emotion recognition.
Interestingly altruists’ blood flow to the right amygdala, as well as the right lateral prefrontal cortex, was consistently higher than controls’ when shown fearful facial expressions. Furthermore, controls showed higher blood flow to the left amygdala when angry faces were displayed than altruists. Results from the emotion recognition and behavioral tasks matched fMRI results in that altruists recognized fear better than controls, while controls were better able to recognize angry faces.
Both studies support previous research suggesting a relationship between psychopaths and functional impairment of parts of the amygdala. In “Neural and Cognitive Characteristics of Extraordinary Altruists”, Marsh et al. showed the farther an individual was from altruism on the spectrum, the higher reactivity there was to anger in the amygdala; while Carre et al. in “The Neural Signatures of Distinct Psychopathic Traits” demonstrated a significant positive association between the lifestyle aspect of psychopathy and higher amygdala reactivity to angry faces. Together, these findings suggest that the amygdalae of psychopaths may at times be either hyporeactive or hyperreactive depending on the situation, discrediting the theory of a completely hyporeactive amygdala in psychopathic brains. There were some limitations to each study, as Carre et al. pointed out, none of the participants scored unusually high in psychopathic traits, possibly skewing the results. Also, Marsh et al. believe further research on altruists should be completed in the future, now that it has been shown they can be distinguished from the general population.
Different results may be found by intentionally placing diagnosed psychopaths in the pool of participants in a repeat of both studies. Further, although abnormalities in the amygdala seem to be contributing to the development of this personality disorder, more research needs to be completed looking at other areas of the brain. A good place to start may be the right lateral prefrontal cortex, where Marsh et al. found functional differences compared to controls. Carre et al. found there were functional differences in the ventral striatum in response to reward, another area that should be of interest.
This data further backs the argument that criminal behavior can be explained in terms of structural or functional differences in the brain. Psychopathy is a medical condition, and should be treated as such, maybe the “insanity” defense as it stands is too strictly defined. Rather than locking criminal psychopaths away in prison (or any other mentally ill individual), we should instead be using those resources to find ways to help or treat them; with this research may find ways to reduce future crime rates due to mental illness. As of today, the U.S. legal system does not give as much weight to the vast amount of research and empirical findings as it probably should. Empirical psychological research is objectively measurable, and deserves to be held higher in the eyes of the judicial branch.
Carre, J., Hyde, L., Neumann, C., Viding, E. & Hariri, A. (2013). The Neural Signatures of Distinct Psychopathic Traits. Social Neuroscience, 8(2), 122-135.
Marsh, A., Stoycos, S., Brethel-Haurwitz, K., Robinson, P., VanMeter, J., & Cardinale, E. (2014). Neural and Cognitive Characteristics of Extraordinary Altruists. PNAS 2014, 111(42), 15036-15041.