In this chapter, the term ‘intellectual disability’ is used to refer to people with global cognitive problems and associated problems with daily living skills, whose difficulties were apparent before 18 years of age. In the UK, in the past, this group of people were referred to as having a mental handicap. In the USA and many other countries, the term ‘mental retardation’ is used. The term ‘learning disability’ is also commonly used in the UK to refer to this group, but in the USA, it refers to people with specific deficits in scholastic skills (e.g. dyslexia, dyscalculia). ICD- 10 uses the term mental retardation, but the definition and the subclassifications set out (mild, moderate, severe and profound) are the same as for intellectual disability in the UK (World Health Organization, 1988; Department of Health, 2001).

Intellectual disability

People with an intellectual disability can experience difficulties leading to an emergency presentation to mental health services for the same reasons as people who do not have an intellectual disability (for example, mood disorders, psychoses). However, their typical presentation might be modified by the presence of intellectual disability (Marston et al, 1997; Clarke & Gomez, 1999). They might experience emergencies related to problem behaviours (notably aggressive, self-injurious or sexually inappropriate behaviour) or a seizure disorder. Medical emergencies in people with an intellectual disability can result in a presentation that can be difficult to distinguish from manifestations of psychiatric or behaviour disorder. The special needs or attributes of people with intellectual disability that need to be taken into account when dealing with emergencies comprise the ‘four Cs’: communication difficulties, capacity to consent, comorbid conditions and complicating effects on symptoms.

Communication difficulties and reliance on other sources of information

A person with intellectual disability might not be able to give an account of recent problems or experiences as easily as a non-disabled person. People with more severe intellectual disabilities might have no, or very limited, ability to use spoken communication. Reliance might have to be placed on non-verbal methods of communication (e.g. appearance, behaviour, bodylanguage, use of signs or pictures to communicate) and on history obtained from carers and other people in close contact with the patient.