Overactive disorder associated with mental retardation and stereotyped movements
Coding guidance (WHO 2019)
An ill-defined disorder of uncertain nosological validity. The category is designed to include a group of children with severe mental retardation (IQ below 35) who show major problems in hyperactivity and in attention, as well as stereotyped behaviours. They 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). This syndrome is also often 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.