A term used by some specialists to describe cases of autism where the individuals' full-scale IQ score is below 70, i.e. in the disabled range. This is not a formal diagnostic category, but rather a term sometimes used informally in diagnosis as well as in everyday situations and research. See also high-functioning.

A widely used brain imaging technique that passes magnetic currents harmlessly through the brain to reveal the structural anatomy, and how particular regions may be altered (e.g. larger or smaller than is typical) in conditions such as autism.

An intense response to overwhelming situations which can look like a temper tantrum. An autistic person may shout, cry or scream, kick, lash out or bite, or a combination of these, as a way to express their distress, stress or anxiety.

Refers to a person’s beliefs, memories, desires, intentions and feelings.

A study, usually with a small number of participants, often in the same setting, who start the intervention after having been observed beforehand for differing lengths of time. For example one may start the intervention after 3 weeks, one after 5 weeks and one after 7 weeks. If each is seen to respond positively to the intervention this provides evidence that it is effective and the changes seen are not due to another factor.

Families with more than one child/family member on the autism spectrum. The fact that autism quite commonly affects several family members provides strong evidence that genetic factors play a role in causing autism.

Changes in the sequence of units making up the genes in a person’s DNA. Sometimes parts of a gene may become duplicated, deleted or changed in other ways. Such genetic variation will affect the proteins that are coded for by the DNA, influencing how parts of the body, including the nervous system develop, with consequent effects on behaviour or traits.

A UK framework for the identification, assessment, diagnosis and access to early interventions for pre-school and primary school aged children with autism spectrum conditions.

The National Autistic Society was founded in 1962 as an organisation for people with autism, their families and carers. It provides advice and support for families and autistic individuals, promotes exchange of ideas and information, pioneers important national and international initiatives and raises public consciousness about the needs of people on the autism spectrum.

A term describing interventions that support the development of target skills within a child's everyday environment, or in naturally occurring situations. They may employ some behavioural principles, but are more child-centred than adult-directed. (See also adult-directed approach; child-centred approach.)