Blaming the parts instead of the person: understanding and applying neurobiological factors associated with psychopathy.

• Author: Freedman, Lauren F.
• Position: Canada

Introduction

Psychopathy is currently understood as a cluster of behaviours and personality traits that are typically viewed in a negative light (Hare 1993). Psychopaths are described as callous individuals who are aware of their wrongdoings but lack remorse. They are individuals who fail to accept responsibility for their actions, while priding themselves on having the skill to avoid sanctions (Cleckley 1982). They possess superficial charm and are able to convey the impression that they are agreeable individuals; however, they also have the ability to lie with remarkable conviction. They have average-to-above-average intelligence and are typically unreliable (Cleckley 1982).

Based on the premise that psychopaths do not have a distorted sense of reality and appear to be both rational and aware of their actions, the mental health community classifies psychopaths as sane (Hare 1993). Furthermore, the mental health community regards the conduct of psychopaths as being derived from a combination of cold rationality and an inability to view others as sensitive beings (Arrigo and Griffin 2004). As a result, psychopathy continues to be understood as a set of traits and behaviours that exist independently from any mental disorder.

However, if psychopathy is not associated with a mental disorder, the question arises as to what exactly does spur the development of these traits and behaviours? There tends to be a natural inclination to presume that psychopathy is related to upbringing and, more specifically, that individuals who experience difficult childhoods are more prone to psychopathy (Hare 1993; Petrunik and Weisman 2005; Marshall and Cooke 1999). It has been argued, however, that many people who experience troubled childhoods do not grow up to become psychopaths and, more importantly, there are a great number of psychopaths who were raised in loving and nurturing environments (Hare 1993). While it is true that the presence of antisocial parents, parental alcoholism, inconsistent discipline, and lack of supervision are related to psychopathy, it seems more apparent that these factors exacerbate the antisocial behavioural patterns of psychopaths rather than explain the behavioural deficits common to psychopaths (Blair, Mitchell, and Blair 2005). It seems clear, therefore, that psychopathy cannot be attributed solely to environmental factors and that there must be other factors that can more satisfactorily explain this set of traits and behaviours.

While environmental factors fail to provide a compelling explanation for the development of psychopathy, these factors are clearly connected to the development of antisocial personality disorder (APD). In a recent study of the relationship between APD and psychopathy, it was found that the two conditions share a common genetic factor (Larsson, Tuvblad, Rijsdijk, Andershed, Grann, and Lichtenstein 2007). Significantly, it was concluded that psychopaths are not sensitive to environmental stimuli in the development of their behavioural patterns, whereas a greater proportion of those who were subjected to environmental strains developed APD than those who were not exposed to such stressors (Larsson et al. 2007). Therefore, it appears that while environmental factors influence the development of APD, the same is not true for psychopathy. This suggests that APD may be characteristic of behavioural adaptations, whereas psychopathy is more likely to be innate to the individual. Thus APD and psychopathy are bound by a common genetic factor but they differ insofar as APD is susceptible to external triggers, while psychopathy is not.

Similarly, Blair (2006) has acknowledged the possibility that there is a genetic factor that predisposes individuals with psychopathy to develop antisocial behaviour. While he argues that it is unlikely that a genetic factor causes antisocial behaviour, genetics are recognized as a possible moderating factor in the expression of antisocial behaviour. More specifically, it is argued that when individuals with certain genetic predispositions are placed in stressful environments, genetics may play a role in determining the probability that those individuals will learn an antisocial, rather than socially acceptable, method of achieving their goals (Blair 2006).

The focus of this article is to argue that individuals with psychopathy are neurobiologically different from their non-psychopathic counterparts and that these differences affect their propensity to violate the law. The article provides an in-depth analysis of neurobiological research relating to selected cognitive and affective deficits common to psychopaths. It commences with an examination of the fear-processing deficits associated with psychopathy and continues with a discussion of learning deficits and neurotransmitter abnormalities. The implications of each of these various neurobiological factors are then analysed in the context of their relationship to criminal behaviour, and it is asserted that individuals with psychopathy should not be held fully responsible for their antisocial behaviour.

Neurobiological irregularities

Fear-processing deficits

One of the most striking characteristics common to psychopaths is their general failure to express fear. A great deal of research has been conducted to determine whether psychopaths are, in fact, devoid of fear and, if so, why this might be the case. While there is overwhelming agreement that psychopaths have fear-processing deficits (Birbaumer, Veit, Lotze, Erb, Hermann, Grodd, and Flor 2005; Lorenz and Newman 2002; Patrick, Bradley, and Lang 1993; Dolan and Fullam 2006; Dolan and Fullam 2006), the cause of these deficits is less clean

Nearly 15 years ago, it was revealed that the startle reflexes of psychopaths differ from those of their non-psychopathic counterparts. One notable study indicated that, unlike "normal" individuals, when psychopaths are shown pleasant, unpleasant, and neutral pictures, their blinking patterns and heart rates remain constant (Patrick et al. 1993). This finding suggests that psychopaths are not emotionally affected by unpleasant images and do not exhibit signs of fear. More than a decade later, similar experiments were conducted, with a new focus on measuring the brain activity of psychopaths during the presentation of images that ranged through various degrees of unpleasantness and were accompanied by the application of painful pressure to the subject. The findings of these studies indicate that psychopaths have highly unusual brain activation patterns, as some parts of the emotion-related brain circuit were found to be significantly overactive, while other parts of the same circuit were severely underactive (Birbaumer et al. 2005; Muller, Sommer, Wagner, Lange, Taschler, Roder, Schuiererc, Kleina, and Hajaka 2003). Thus, it would appear that psychopaths do not exhibit normal physiological responses to fear.

Psychopaths also show abnormal physiological responses to frightening sentences. Upon listening to sentences designed to elicit fear, the muscular responses of psychopaths remain largely unchanged. It is common for people to unconsciously tense their muscles when they are afraid, yet psychopaths failed to show significant muscular responses to frightening sentences (Patrick, Cuthbert, and Lang 1994). This suggests that psychopaths have difficulty interpreting such sentences at an emotional level. This research further supports the finding that psychopaths do not respond to fear in the same way as do most other individuals.

In addition to exhibiting diminished physiological responses to fear, there is evidence that psychopaths have difficulty identifying fear expressed by others. Research has indicated that psychopaths have difficulty recognizing fear and sadness in facial expressions, typically misinterpreting them as neutral (Dolan and Fullam 2006). This is particularly noteworthy in light of the fact that psychopaths have no difficulty identifying happy facial expressions (Dolan and Fullam 2006). Thus, while psychopaths are capable of experiencing happiness and recognizing it in others, they appear to have a fear-processing deficit that prevents them from experiencing fear themselves and from recognizing fear in the facial expressions of others.

Despite the fear-processing deficits common among psychopaths, there is evidence to suggest that they do have some conception of the emotion of fear. It might be expected that because psychopaths have difficulty experiencing fear or recognizing it in facial expressions, they would also have difficulty identifying frightening words; yet, this is not the case (Lorenz and Newman 2002). Research shows that psychopaths are able to differentiate between a word that may elicit fear and one that would not. This counter-intuitive ability introduces a central paradox of psychopathy: namely, psychopaths are able to identify emotional cues, but those cues are meaningless to the psychopath and cannot be used to guide their personal judgements or behaviours (Lorenz and Newman 2002).

It has been suggested that the atypical physiological responses of psychopaths to fear may be associated with dysfunction of the amygdala and/or orbitofrontal cortex (OFC) of the brain (Muller et al. 2003). The amygdala, which is located in the temporal lobe of the brain, is associated with impaired startle reflexes and poor recognition of facial expressions, particularly that of fear (Blair 2006). In contrast, the OFC, which is part of the frontal lobe, is associated with the anticipation of punishment and reward (Birbaumer et al. 2005). The anticipation of negative responses plays an integral role in fear, as fear is typically premised upon the realization that something negative may happen. This results in anxiety until the negative event occurs or until an intervention takes place to alleviate the anxiety (i.e., it becomes clear that the negative event will not occur). As a result...