Language functions in Huntington's disease

A comprehensive language test battery (Aachen Aphasia Test) was administered to 45 patients in the early, middle or later stages of Huntington's disease (HD) and to 20 control subjects. In spontaneous speech, many HD patients exhibited a loss of conversational initiative. Dysarthria was a common finding. Reading skills were found to be impaired mainly as a consequence of dysarthria; some HD patients displayed visual dyslexia. In addition to the characteristic disturbances of writing skills due to the choreiform movement disorder, the writing of HD patients with advanced dementia indicated constructional dysgraphia, characterized by frequent omissions, perseverations and substitutions. HD patients exhibited no evidence of word-finding difficulty or other semantic deficits in spontaneous speech. There was, however, a marked impairment in visual confrontation naming, with a significant rise in naming error rate as the disease progressed in severity. In most instances, the inappropriate names referred to an object visually similar to the target object, suggesting that visual misperception is the major cause of the naming disorder in HD. Syntactical structure of spontaneous speech was typically reduced to short, simple sentence construction. Verbal stereotypes were only rarely encountered and occurred late in the course of the disease. Tests of language comprehension reflected the general degree of dementia. It is concluded that there are no primary language changes in HD. Instead, a variety of language impairments develop secondary to other neurological and neuropsychological changes.