Clinical features
The most obvious manifestation of learning disability is low performance in all intellectual tasks including learning, short-term memory, the use of concepts and problem solving.
Specific abnormalities may lead to particular difficulties. For example, lack of visuo-spatial skills (visual perception of spatial relationships among objects) may cause practical difficulties such as inability to dress or there may be disproportionate difficulties with language or social interaction, both of which are strongly associated with behavioural disorder.
Mild learning disability [IQ 50-70]
People with a mild learning disability account for about 85% of people with learning disability. Usually their appearance is normal and any sensory or motor deficits are slight. Most people in this group develop more or less normal language abilities and social behaviour during the pre-school years and their learning disability may never be formally identified. In adult life, most people with mild learning disability can live independently in ordinary surroundings, though they may need help in coping with family responsibilities, housing and employment, or when under unusual stress.
Moderate learning disability [IQ 35-49]
People with a moderate learning disability account for about 10% of people with learning disability. Most have better receptive than expressive language skills, which is a potent cause of frustration and behavioural disorder. Speech is usually relatively simple and better understood by people who know the person well. Many make use of simplified signing systems such as the Makaton sign language. Activities of daily living such as dressing, feeding and attention to hygiene are usually acquired over time but extended activities of daily living such as use of money and road sense generally require support. Similarly, supported employment and supported education are the rule.
Severe learning disability [IQ 20-34]
People with a severe learning disability account for about 3-4% of people with learning disability. Many people in this group can be helped to look after themselves but only under close supervision and to communicate in a simple way. They may be able to undertake simple tasks and engage in limited social activities, but they need supervision and a clear structure to their lives. People with severe learning disability are likely to be incontinent, have difficulty walking and severe behavioural disorder.
Profound learning disability [IQ below 20]
People with a profound learning disability account for 1-2% of people with learning disability. Their development approximates to that of a 12-month-old infant and therefore they require help and supervision for even the simplest activities of daily living.
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Amended April 2008
