The purpose of this study was to compare the language and cognitive profiles of four progressive nonfluent aphasia (PNFA) patients with 25 probable Alzheimer's disease (pAD) patients, and to identify the distinct cortical defects associated with cognitive deficits in PNFA using positron emission tomography (PET). Longitudinal observations of PNFA patients revealed progressively telegraphic speech and writing and a gradual deterioration of sentence comprehension, but memory and visual functioning were relatively preserved. Direct contrast with PAD patients revealed that PNFA patients are significantly impaired on grammatical phrase structure aspects of sentence comprehension and expression, phonemic judgments, repetition, and digit span, but not on other cognitive measures. PET studies of PNFA revealed reduced cortical activity throughout the left hemisphere. In addition, there was a prominent defect in left superior and middle temporal and inferior frontal regions of PNFA patients that differed significantly from the distribution of regional cerebral dysfunction in pAD. We conclude that PNFA is associated with a distinct profile of language and cognitive difficulty, and that this pattern of impairment is related to cortical dysfunction in a specific distribution of the left hemisphere.

Verbal fluency (semantic category naming and letter fluency) and nonverbal fluency (semantic category drawing and design fluency) were measured in mildly and moderately demented patients with probable dementia of the Alzheimer type (pDAT), and related to age at onset, disease duration, and disease severity. Group and individual patient analyses revealed impairments within verbal and nonverbal modalities that were most severe on semantic category fluency tasks. Detailed assessments of errors emphasized the role of compromised semantic memory in pDAT patients' impaired fluency, regardless of the modality of response. Fluency performance was related to dementia severity but not to age of onset or disease duration. It is concluded that deficits on measures of fluency in pDAT are due in large part to semantic memory impairments and that fluency may be useful for following disease progression.Verbal fluency deficits have been well documented in patients with probable dementia of the Alzheimer type (pDAT). Reduced verbal fluency has been reported on a letter fluency task on which patients were asked to name words beginning with a target letter (

We assessed sentence processing in Alzheimer's disease (AD) with measures of sentence-picture matching, grammaticality judgments of sentences, and sentence completion. The results demonstrated significant and consistent difficulty with a grammatical feature of sentences on all three experiments. This impairment could not be explained by factors such as sentence length, dementia severity, or a short-term memory deficit and was independent of difficulty interpreting the meanings of words. We hypothesize that AD patients are impaired at appreciating the conceptual relations that underlie certain grammatical features of sentences.

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