What are Externalizing Disorders?
Recent evidence suggests that substance abuse, oppositional defiance disorder, conduct disorder, antisocial personality disorder, and psychopathy are part of a similar continuum of disorders (Krueger, Markon, Patrick, & Iacono, 2005). This spectrum of disorders has been called the externalizing spectrum (Krueger et al., 2005). Krueger et al. (2002) found that the externalizing factor is highly heritable and evidence suggests that environment seems to affect the actual disorder presentation. The two factors that are common to all externalizing disorders are lack of behavioral restraint, and some level of aggression (Kruger et al., 2002). Kruger et al. (2005) compared discrete latent class model to a continuous latent trait model and results showed that the latent trait model was more adequate. This means that lower levels of externalizing disorders would be less severe disorders such as substance abuse and high levels would be more severe disorders such as psychopathy.
Picture of Illicit Drugs Retrieved from http://www.bbc.co.uk/radio4/womanshour/03/media/drugs.jpg
According to the DSM-IV substance abuse is characterized by the continued use of a substance even though it is causing legal or social problems (1994). Substance dependence is characterized by tolerance and withdrawal. In other words, more and more of the drug is needed and when the drug is not used there are physiological and psychological costs. Oppositional defiant disorder (ODD), conduct disorder (CD), and antisocial personality disorder (APD) are characterized by differing levels of antisocial behavior. ODD involves not following rules given by adults, CD involves violation of society’s rules, and APD involves a serious violation of society’s rules and often involves a lack of remorse. Psychopathy predates the DSM and is not part of the current DSM (Kiehl, 2006). Psychopathy affects 15-20% of criminal populations and around 1% of the general population (Hare, 2003). Psychopathy is considered to be a more severe form of antisocial personality disorder (APD). APD is present in close to 80% of prison populations while psychopathy is present in a smaller number of cases. Psychopathy is usually assessed by the Hare Psychopathy Checklist Revised (PCL-R; Hare, 2003). A factor analysis of the PLC-R yielded two factors; one is associated with difficulties with emotion and personal relationships, while the other is related to impulsivity and antisocial behaviors (Harpur, et al. 1988).
The Hare Psychopathy Checklist Revised is one way to assess psychopathy.