Introduction

Little controversy surrounds the notion that persons with intellectual disabilities (ID) may engage in disruptive and challenging behaviours. One of the common referral queries to clinicians of people with ID – ‘Is this a mental illness or just a problem behaviour?’ – tends to stir up more discussion. At one extreme, attempts to understand maladaptive behaviours are merely descriptive and simply default to the ID itself. For example, aggression or self-injurious behaviour is said to be a product of the individual's cognitive disability and does not warrant a ‘diagnosis’. At the same time, the degree to which an individual is held accountable for his behaviour is also placed into consideration, as is the appropriateness of pharmacotherapy, depending on the answer to the referral question.

At the other extreme, an attempt is made to identify a syndrome or disorder within which the behaviour in question can be understood — to cast the behaviour at issue as the manifestation of a physiological abnormality. For example, the self-injurious or aggressive behaviour may be viewed as a symptom of a mood disorder (see also Chapter 4 by Hemmings). Such attempts clearly carry therapeutic implications, and can be traced back to the origins of the psychiatry of ID.