Language function and dysfunction in corticobasal degeneration

Objectives: The authors assessed language functioning in corticobasal degeneration (CBD), an area that has received little systematic study. Aphasia has been reported occasionally, and the authors hypothesized that appropriate assessments would reveal at least mild language impairment, particularly affecting phonologic (sound-based) processing, even in cases without frank aphasia. Methods: A series of 10 unselected patients with CBD (one with pathologic confirmation) were administered neuropsychological tests assessing the following aspects of cognitive functioning: verbal fluency, naming, reading, oral spelling, auditory-verbal short-term memory, phoneme blending and segmentation, visuospatial skills, and semantic memory. Results: Phonologic and spelling impairments were prevalent, even in nonaphasic patients. The prevalence of visuospatial, constructional, and frontal impairments, demonstrated in previous research, was also replicated. A minority of patients had deficits in semantic memory, naming, and reading, but the impairments were usually mild. Conclusions: The authors found phonologic impairment to be a typical feature of CBD. There is substantial overlap between progressive nonfluent aphasia and CBD, and the linguistic impairment can be thought of as a continuum, with mild phonologic impairment at one end and severe aphasia at the other.