Certain infectious and parasitic diseases

F84.4 Overactive disorder associated with mental retardation and stereotyped
movements
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.
F84.5 Asperger's syndrome
A disorder of uncertain nosological validity, characterized by the same type of
qualitative abnormalities of reciprocal social interaction that typify autism,
together with a restricted, stereotyped, repetitive repertoire of interests and
activities. It differs from autism primarily in the fact that there is no general delay
or retardation in language or in cognitive development. This disorder is often
associated with marked clumsiness. There is a strong tendency for the
abnormalities to persist into adolescence and adult life. Psychotic episodes
occasionally occur in early adult life.
Autistic psychopathy
Schizoid disorder of childhood
F84.8 Other pervasive developmental disorders
F84.9 Pervasive developmental disorder, unspecified
F88
F89
Other disorders of psychological development
Developmental agnosia
Unspecified disorder of psychological development
Developmental disorder NOS
Behavioural and emotional disorders with onset usually
occurring in childhood and adolescence
(F90-F98)
F90 Hyperkinetic disorders
A group of disorders characterized by an early onset (usually in the first five
years of life), lack of persistence in activities that require cognitive involvement,
and a tendency to move from one activity to another without completing any one,
together with disorganized, ill-regulated, and excessive activity. Several other
abnormalities may be associated. Hyperkinetic children are often reckless and
impulsive, prone to accidents, and find themselves in disciplinary trouble because
of unthinking breaches of rules rather than deliberate defiance. Their
relationships with adults are often socially disinhibited, with a lack of normal
caution and reserve. They are unpopular with other children and may become
isolated. Impairment of cognitive functions is common, and specific delays in
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