Emotional Impulsiveness: A Link to Violent Criminality in the Personality Disordered?

Mini Review

It is well-established and beyond dispute that some individuals diagnosed with personality disorders are predisposed to offend violently [1]. But what is it about personality disorder (PD) that predisposes such individuals to violence? Personality disorders are not alone in predisposing to violence, which has been found to be linked to a range of other mental disorders, including schizophrenia (odds ratio 7.4) [2], bipolar disorder (odds ratio 5.8) [3], and depression (odds ratio 3.0) [4]. In reviewing the functional link between PD and violence, Duggan and Howard [5] gave the example of a patient who meets criteria for both narcissistic and paranoid PDs, has multiple (DSM-IV) Axis I conditions including substance use and post-traumatic stress disorder (PTSD) and is prone to violence. They ask: “Does one give precedence to a blow to the individual’s self- esteem (narcissism), or to a suspiciousness of the motives of others (paranoid traits), his or her substance abuse or the activation of PTSD symptoms in explaining his or her violent behaviour?” (p.25). In other words, which condition has causal primacy in determining the links between mental disorder and violent behavior? Posing the question in this way presupposes that the link between psychiatric disorder and violence operates at the level of individual diagnostic categories. However, the fact that a predisposition to violence transcends particular categories of psychiatric illness should alert us to the possibility that we need to look at the link between psychiatric disorder and violence from a different perspective. The recently proposed Hierarchical Taxonomy of Psychopathology (HiTOP: [6]) model offers such an alternative perspective. In this model, symptoms/signs (level 1) are nested within maladaptive traits (level 2) which in turn are nested within syndromes/disorders (level 3). At a higher level of the hierarchy (level 5) are situated broad spectra, namely internalizing pathology, externalizing pathology (comprising disinhibited and antagonistic externalizing), thought disorder (i.e., psychosis spectrum disorders), and detachment (i.e., pathological introversion). At the highest level of the hierarchy are super-spectra, higher-order dimensions of psychopathology. One such super- spectrum is overall psychopathology (p) [7]. It has been proposed that higher p scores are associated with more life impairment, greater familiality, worse developmental histories, and more compromised early-life brain function [7]. Overt acts of aggression and violence are located at the bottom level of this hierarchy (signs and symptoms), but a predisposition to violence can be seen as related to all higher levels of the hierarchy. Thus violence is associated, at level 2, with maladaptive traits associated, in the Five Factor Model (FFM) of personality, with low Conscientiousness, low Agreeableness and high Neuroticism [8]. Of general traits included in the FFM, Antagonism, which includes traits such as suspiciousness, combativeness, deceptiveness, lack of empathy and arrogance, is the most strongly related to interpersonal violence in civil psychiatric patients, with Neuroticism also related but to a lesser degree [9]. At level 3, violence is associated with a wide variety of psychiatric syndromes, most notably, in the context of personality disorders, with co-occurring antisocial and borderline personality disorders [10]. At the level of spectra (level 5), violence can be seen as associated with disinhibited and antagonistic externalizing, and with aspects of internalizing (e.g. distress).

At the highest level of the HiTOP hierarchy, higher- order dimensions of psychopathology or ‘super-spectra’, violence is related to overall level of psychopathology (p) [7]. An important putative contributor to p is emotional impulsiveness, defined as the tendency to act rashly, precipitately, and without regard for negative consequences under the pressure of emotional arousal. The current author [11] has reviewed research findings suggesting that emotional impulsiveness in adulthood has its origins in childhood temperament and, manifested in the propensity to experience and express anger, runs continuously through the developmental fabric of severe personality disorder, from early through late childhood, into adolescence and adulthood. Evidence is further reviewed suggesting that emotional impulsiveness is associated with severe personality disorder, and accounts, at least in part, for the propensity to violence shown by those with severe personality disorder. Other individual factors contributing to p, and hence to violence risk, are traits associated with psychopathy and delusional thinking [12, 13]. It is important to note, however, that these characteristics of the individual’s personality operate in concert with contextual factors, such as alcohol use and interpersonal stress, to increase his/her risk of violence. Thus a violent outcome is never entirely predetermined by an individual’s personality, but is dependent on the context (e.g. a private vs. public space) in which the individual finds him/herself. Even the most emotionally impulsive persons would, if they avoided contexts in which they would be at risk of committing a violent act, be immune to the commission of such an act.