Information processing speed in Friedreich's ataxia.

Three patients with Friedreich's ataxia and six controls matched by age and vocabulary and information scores on the Wechsler Adult Intelligence Scale-Revised were administered a measure of short-term memory scanning. Patients with Friedreich's ataxia demonstrated a deficit in information processing speed in the relative absence of impairment in attention, memory, language, judgment, reasoning, and other cognitive functions. The short-term memory scanning procedure may be useful in documenting cognitive slowing and in distinguishing this impairment from the motor abnormality often associated with a subcortical brain disorder.