The consequence of markedly low intellectual functioning, in past times referred to as mental subnormality. There is a distinction between impairment (a biological deficit), disability (the functional consequence) and handicap (the social consequence).
In general, people with learning disability want to be seen as themselves; to learn new skills; to choose where to live; to have good health care; to have girlfriends or boyfriends; to make decisions about their lives; and to have adequate finances. They may live at home with their families, or in small residential units with access to work and leisure and to other people in ordinary communities.
Those with moderate disability may achieve basic functional literacy (recognition of name, common signs) and numeracy (some understanding of money) but most have a life-long dependency for aspects of self-care (some fastenings for clothes, preparation of meals, menstrual hygiene, shaving) and need supervision for outdoor mobility. People with profound learning disability are usually unable to communicate adequately and may be seriously movement-impaired. They are totally dependent on others for care and mobility.
Profound learning disability affects about 1 in 1,000; severe learning disability 3 in 1,000; and moderate learning disability requiring special services, 1 per cent. With improved health care, survival of people with profound or severe learning disability is increasing.
Many children with profound or severe learning disability have a diagnosable biological brain disorder. Forty per cent have a chromosome disorder – see CHROMOSOMES (three-quarters of whom have DOWN'S SYNDROME); a further 15 per cent have other genetic causes, brain malformations or recognisable syndromes. About 10 per cent suffered brain damage during pregnancy (e.g. from CYTOMEGALOVIRUS (CMV) infection) or from lack of oxygen during labour or delivery. A similar proportion suffer postnatal brain damage from head injury – accidental or otherwise – near-miss cot death or drowning, cardiac arrest, brain infection (ENCEPHALITIS or MENINGITIS), or in association with severe seizure disorders.
Explanations for moderate learning disability include Fragile X or other chromosome abnormalities in a tenth, neurofibromatosis (see VON RECKLINGHAUSEN'S DISEASE), fetal alcohol syndrome and other causes of intra-uterine growth retardation. Genetic counselling should be considered for children with learning disability. Prenatal diagnosis is sometimes possible. In many children, especially those with mild or moderate disability, no known cause may be found.
EPILEPSY affects 1 in 20 with moderate, 1 in 3 with severe and 2 in 3 with profound learning disability, although only 1 in 50 with Down's syndrome is affected. One in 5 with severe or profound learning disability has CEREBRAL PALSY.
Over half of those with profound or severe – and many with moderate – learning disability show psychiatric or behavioural problems, especially in early years or adolescence. Symptoms may be atypical and hard to assess. Psychiatric disorders include autistic behaviour (see AUTISM) and SCHIZOPHRENIA. Emotional problems include anxiety, substance dependence and depression. Behavioural problems include tantrums, hyperactivity, self-injury, passivity, masturbation in public, and resistance to being shaved or helped with menstrual hygiene. There is greater vulnerability to abuse, with its behavioural consequences.
Respite care is arranged with link families for children, or staffed family homes for adults, where possible. Responsibility for care is with social services departments, which can advise also about benefits.
Special educational needs should be met in the least restrictive environment available, allowing access to the national curriculum with appropriate modification and support. For older children with learning disability, and for young children with severe or profound learning disability, this may be in a special day or boarding school. Other children can be provided for in mainstream schools with extra classroom support.
In the UK, pupils with learning disability are entitled to remain at school until the age of 19, and most with severe or profound learning disability do so. Usually, those with moderate learning disability move to further education after the age of 16.