When more yields less: speaking and writing deficits in nonfluent progressive aphasia

Fourteen patients with nonfluent progressive aphasia (NFPA) performed a picture description task in both spoken- and written-output conditions, as well as tests of confrontation naming, spelling to dictation and reading aloud of single words and text. Relative to controls, the patients' spoken and written picture descriptions were reduced in length, speed and amount of information. Of particular interest, and accounting for the first part of the article's title, was a pervasive pattern of poorer spoken and written output associated with the requirement to produce more; this was true when 'more' meant either (a) longer vs. shorter single words or (b) connected language vs. single words. Deficits in spoken and written naming were largely parallel and modality-specific output impairments (such as dysarthria in speech or letter-formation problems in writing) seemed to account for the minority of cases who exhibited a discrepancy. Most patients showed no evidence of agrammatism or reduced verb production in their speech, which typically had normal proportions of content and function words as well as nouns and verbs. By contrast, some degree of telegraphic output was observed in the written narratives of a number of patients. Our results argue against several candidates for the main functional locus of impairment in NFPA, but it is likely that deficits in grammatical processing, working memory, planning/executive skills, speech motor abilities and phonological processing all play a role.