Learning Disabilities & Serious Crime: Murder

Disruptive behaviour disorders have been suggested to be a focus of attention in learning disability psychiatry (Read, S, Disruptive Behaviour Disorders, Wiley, 2007). They comprise a grouping of conduct and personality disorders which emphasises the similarities between the various component diagnoses of: Oppositional Defiant Disorder Conduct Disorder Anti-social Personality Disorder Intermittent Explosive Disorder (DSMIVR, 2000) (or Emotionally Unstable Personality Disorder, Explosive Type (WHO, 2002) Similarities include irritability, explosive type aggression, high levels of arousal, over-activity, and stereotyped behaviour. What this review of murder and learning disability intends to do is to examine the associated psychiatric disorders including personality and conduct disorders of those who commit such crimes. It is the authors’ intention that this paper will be one of three reviews; the second and third papers examining arson and learning disability, and sexual offences and learning disability respectively. Learning disability itself and also mental illness have both been implicated in the past as causative factors in the production of homicide. This review aims to examine these factors alongside those of personality and conduct disorders in the inception of such an anti-social act. People with a learning disability are involved in sexual offences, arson and homicide. If these crimes are arranged in a hierarchy of gravity – from sexual offences at the lower end of the hierarchy, through arson to homicide at the upper end, it can be postulated that as the seriousness of the crime increases, so the disproportionate contribution to it by learning disabled people dwindles. Wherein lies those associations that remain? The answer lies in the association of learning disability with disruptive behavioural disorders, that is psychiatric disorders of conduct and personality. These seem to be the essential intermediary factors which provide for the association of learning disability with murder. That mental illness plays only a minor role is supported by Whitaker and Read (2007) who found, in an extensive literature review, very little evidence to suggest that learning disabled people experienced increased prevalence of mental illness. To suffer a disruptive behaviour disorder may be collateral consequence of arrested or incomplete development of the brain which is characteristic of learning disability. However, it may also be a consequence of aberrant learning and other environmental and social factors influencing childhood development. This review paper unpicks these difficulties in interpretation of the evidence surrounding learning disability and murder