Overactive disorder associated with mental retardation and stereotyped movements is a pervasive developmental disorder (PDD) in Chapter V(F) of the tenth revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10); its diagnostic code is F84.4.
ICD-10 clinical description
This is an ill-defined disorder of uncertain nosological validity. The category is included here because of the evidence that children with moderate to severe mental retardation (IQ below 50) who exhibit major problems in hyperactivity and inattention frequently show stereotyped
behaviours; such children tend not to benefit from stimulant drugs (unlike those with an IQ in the normal range) and may exhibit a severe dysphoric
reaction (sometimes with psychomotor retardation) when given stimulants; in adolescence the overactivity tends to be replaced by underactivity (a pattern that is not usual in hyperkinetic children with normal intelligence). It is also common for the syndrome to be associated with a variety of developmental delays, either specific or global. The extent to which the behavioural pattern is a function of low IQ or of organic brain damage is not known, neither is it clear whether the disorders in children with mild mental retardation who show the hyperkinetic syndrome would be better classified here or under F90.- (hyperkinetic disorders
); at present they are included in F90-.
Diagnosis depends on the combination of developmentally inappropriate severe overactivity, motor stereotypies, and moderate to severe mental retardation; all three must be present for the diagnosis. If the diagnostic criteria for F84.0 (childhood autism), F84.1 (atypical autism) or F84.2 (Rett's syndrome) are met, that condition should be diagnosed instead.