Glossary - M

The information below is reproduced courtesy of The National Autistic Society, the leading UK charity for people with autism (including Asperger syndrome) and their families. It provides information, support and pioneering services, and campaign for a better world for people with autism. Additional information has been added by Kingwood.

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Macrocephaly

Excessive head size.
(NAAR glossary)

Megalencephaly

Having a brain of unusually large size.
(Lindsey, M. Dictionary of mental handicap)

Metabolism

This means tissue change and includes all physical and chemical processes by which the living body is maintained, and also those by which energy is made available for various forms of work.
(Macpherson, G.& (Ed). Black's medical dictionary, 38th Edn)

Metarepresentation

The ability to pretend and to understand pretence in others. This generally develops in the second year of human life but perhaps may be evident earlier. Alternatively, the ability to understand the relationship between a representation and what it represents. This links with metacognition or theory of mind. If metarepresentation is impaired then this affects the person's theory of mind.
(DP)

Microcephaly

Defect in the growth of the brain which causes it to be smaller than a normal brain.
(CaF directory of specific conditions and rare syndromes)

Miller Dieker syndrome

Neural migration disorder in which the convolutions of the cerebral cortex are either completely absent or reduced in number, giving the brain surface a smooth appearance. Problems include developmental delay, microcephaly and seizures.
(CaF directory of specific conditions and rare syndromes)

Monoamine oxidase

Monoamine oxidase (MAO) is a naturally occurring enzyme which is concerned in the breakdown of monoamines.
(Macpherson, G. (Ed). Black's medical dictionary, 38th Edn)

Monoamines

Monoamines play an important part in the metabolism of the brain. There is some evidence that excitement is due to an accumulation of monoamines in the brain. Autistic behaviours might be related to an abnormal functional imbalance among monoamines either at a molecular level or at a system level.
(Macpherson, G. (Ed). Black's medical dictionary, 38th Edn)

Multiple complex developmental disorder

Multiple complex (or multiplex) developmental disorder is a descriptive term for an early-onset syndrome in which there are basic deficits in affective modulation, capacity for relating, and stability of thinking. Characteristics of onset in infancy, sustained limitations in the capacity to form reciprocal relationships, and impoverished affective regulation suggest that MCDD might be appropriately placed in the category of PDD. Until the condition is characterised more clearly it is placed under the wider umbrella of PDD-NOS.
(Cohen, D. J. ;and Volkmar, F. R. ;(Eds). Handbook of autism and pervasive developmental disorders, 2nd Edn)

Multiple disabilities

Simply the presence of more than one disability in the same individual. There are too many possible combinations to list, eg, autism and deafness, physical disability and Down syndrome.
(DP)

Myelin

A fat-like substance wrapped around nerve fibres, acting as an insulator and assisting the rapid transmission of nerve impulses.
(Trevarthen et al. Children with autism)