SURFACE DYSLEXIA IN NONFLUENT PROGRESSIVE APHASIA

This article presents the case of a 59-year-old male, JH, with a 6-yea r history of primary progressive aphasia (PPA), a disorder characteriz ed by isolated language deterioration with relative preservation of ot her cognitive abilities. JH also shows typical features of surface dys lexia, a reading disorder exemplified by the selective preservation of phonological reading. One recent theory is that surface dyslexia in i ndividuals with PPA results from a loss of semantic knowledge. In this paper we consider an additional possibility and present data supporti ng the notion that surface dyslexia may also arise from the malfunctio n in the links between semantic representations and phonology. JH has remarkably preserved lexical semantic knowledge when assessed on tasks that do not require verbal output. Further, item-by-item comparisons of his oral reading and comprehension ability show no significant corr espondence between his reading and semantic knowledge. These Endings l ead us to conclude that, in JH's case, the surface dyslexia is attribu table not to a semantic deficit per se but rather to the inability to access phonological information from semantics. JH's language profile is considered in relation to potential sources of surface dyslexia and other cases of progressive aphasia. (C) 1997 Academic Press