Category-specific deficits have rarely been reported in semantic dementia (SD). To our knowledge, only four previous studies have documented category-specific deficits, and these have focused on the living versus non-living things contrast rather than on more fine-grained semantic categories. This study aimed to determine whether a…

We tested the ability of Alzheimer's patients and elderly controls to name living and non-living nouns, and manner and instrument verbs. Patients' error patterns and relative performance with different categories showed evidence of graceful degradation for both nouns and verbs, with particular domain-specific impairments for living nouns and…

The comprehension of non-literal language was investigated in 20 probable Alzheimer's disease (pAD) patients by comparing their performance to that of 20 matched control subjects. pAD patients were unimpaired in the comprehension of conventional metaphors and idioms. However, their performance was significantly lower in the case of…

We examined the semantic impairment for natural kinds in patients with probable Alzheimer's disease (AD) and semantic dementia (SD) using an inductive reasoning paradigm. To learn about the relationships between natural kind exemplars and how these are distinguished from manufactured artifacts, subjects judged the strength of arguments such as…

This study investigated the relationship between semantic and episodic memory as they support lexical access by healthy younger and older adults and individuals with Alzheimer's disease (AD). In particular, we were interested in examining the pattern of semantic and episodic memory declines in AD (i.e., word-finding difficulty and impaired recent…

We investigated the associations between Boston naming and the animal fluency tests and cortical atrophy in 19 probable AD and 5 multiple domain amnestic mild cognitive impairment patients who later converted to AD. We applied a surface-based computational anatomy technique to MRI scans of the brain and then used linear regression models to detect…

The hypothesis that Alzheimer's disease (AD) degrades semantic representations predicts that AD qualitatively alters spontaneous thoughts. In two experiments contrasting free associations to words with strong (e.g., "bride-groom") versus weak (e.g., "body-leg") associates participants with AD produced less common responses (e.g., "bride-pretty")…

This study examined the impact of various degenerative dementias on access to semantic knowledge and the status of semantic representations. Patients with semantic dementia, primary progressive aphasia, and Alzheimer's disease were compared with elderly controls on tasks of category and letter fluency, with number of words generated, mean lexical…

In a study of the discourse of 100 people with Alzheimer's disease treated for 12 months with donepezil, we observed that, as a group, they used a form of tag, described here as a self-referential tag (SRT), 14 times more frequently than did caregivers. Patients use SRTs to check propositions dependent on episodic memory as in I haven't seen the…

This study examined the nature of verb deficits in 14 individuals with probable Alzheimer's Disease (PrAD) and nine with agrammatic aphasia. Production was tested, controlling both semantic and syntactic features of verbs, using noun and verb naming, sentence completion, and narrative tasks. Noun and verb comprehension and a grammaticality…

This study examines the processing of a specific linguistic distinction, the mass/count distinction, in patients suffering from Alzheimer's disease (AD) and mild cognitive impairment (MCI). Fourteen AD and 10 MCI subjects were tested using a sentence grammaticality judgement task where grammaticality violations were caused by determiner--noun…

We assessed verb fluency vs. noun and letter-based fluency in 199 subjects referred for cognitive complaints including Subjective Cognitive Impairment, Mild Cognitive Impairment, and Alzheimer's disease. ANCOVAs and factor analyses identified verb, noun, and letter-based fluency as distinct tasks. Verb fluency performance in Mild Cognitive…