Autism and ataxia

Non-progressive congenital ataxia has two types:

1. Ataxia diplegia (with lower limb spasticity)
2. Simple ataxia (without spasticity).

Simple ataxia may be subdivided into

1. Congenital cerebellar ataxia” (with uncoordination of voluntary movements)
2. Dysequilibrium syndrome” (with lack of a sense of equilibrium or maintenance of body position in space). Studies have shown cerebellar abnormalities on imaging in only a minority of children with simple nonprogressive ataxia and only half of a series of children with cerebellar hypoplasia were ataxic. It has been suggested that there may be a link between congenital ataxia and autistic features. A study in Sweden has confirmed the association.

The research team assessed 32 people aged 6–21 years with a clinical diagnosis of nonprogressive congenital ataxia.

• 12 had simple ataxia,
• 8ataxic diplegia
• 12 “borderline” ataxia. (The latter group had all had a diagnosis of either simple ataxia or ataxic diplegia at some time but did not fulfil the diagnostic criteria at the time of the study.)

All 12 subjects with simple ataxia, seven of the eight with ataxic diplegia, and nine of the 12 with “borderline” ataxia had learning disability, which varied from mild to profound.

An autistic spectrum diagnosis was made for 16 subjects (atypical autism, 7; autistic features, 4; autistic disorder, 2; Asperger syndrome, 2; “congenital” Rett syndrome, 1). Eight subjects (four in the “borderline” group) had attention deficit hyperactivity disorder. Five subjects in the simple ataxia group had cerebellar abnormalities on imaging. No cerebellar abnormality was demonstrated in subjects in either of the other two groups. Learning disability and autistic spectrum disorder were strongly associated with simple or “borderline” ataxia but no association was demonstrated between cerebellar abnormality on imaging and autistic spectrum disorder. There was only a weak association between ataxic diplegia and neuropsychiatric disorders.