A case of primary progressive aphasia. A 14-year follow-up study with neuropathological findings

Primary progressive aphasia has been clinically defined as a progressive language deficit leading to the dissolution of almost all language functions with relative preservation of other cognitive functions until late in the course of the disease. Two types of language impairment have been described for primary progressive aphasia, which differ with respect to the degree of fluency of spontaneous speech. Whereas some authors have emphasized non-fluency as a defining characteristic of primary progressive aphasia, others have proposed that phonemic rather than semantic paraphasias in naming, both in the fluent and the non-fluent subtype, should be used as a criterion to distinguish primary progressive aphasia from slowly progressive aphasia in other forms of degenerative brain disease. Patients with fluent speech and semantic dementia, as typically seen in Alzheimer's disease, produce semantic paraphasias and circumlocutions rather than phonemic errors in naming. This paper reports the long-term follow-up of a patient with fluent aphasic speech, whose language profile over a decade was similar to that of patients with semantic dementia. Neuropathological examination revealed no evidence of Alzheimer's disease. Pick's disease or Pick variant, but showed spongiform changes of cortical layers (II and III) in temporal and, less severely, in frontal gyri. The present case indicates that semantic dementia is not a reliable indicator of probable Alzheimer's disease and supports the notion that there are different subtypes of primary progressive aphasia which cannot be defined by fluency or by the presence of phonemic paraphasia. Progress in identifying the neuropathological correlates of these subtypes in cases with lobar atrophy and spongiform changes should be expected from hereditary variants of progressive disorder.