M GROSSMAN

We addressed the question of whether Alzheimer's Disease (AD) causes a selective impairment for knowledge of living things. Although we replicated a previous finding that AD subjects name pictures of living things less accurately than pictures of nonliving things, we also failed to observe this selective impairment when we used two new stimulus sets, which more tightly controlled the overall naming difficulty of the living and nonliving items. We conclude that, whereas some individuals may have bona fide selective impairments in semantic memory as a result of herpes simplex encephalitis or head injury, AD does not generally give rise to selective impairments in knowledge of living things.

The authors investigated aspects of interpersonal sensitivity and perspective-taking in relation to empathy, social cognitions, and executive functioning in 26 frontotemporal dementia (FTD) patients. Behavioral-variant FTD (bvFTD) patients were significantly impaired on caregiver assessments of empathy, although self-ratings were normal. Progressive nonfluent aphasia and semantic-dementia samples were rarely abnormal. In bvFTD, empathy ratings were found to be correlated with social cognition and executive functioning measures, but not depression. Voxel-based morphometry revealed that reduced empathic perspective-taking was related to bifrontal and left anterior temporal atrophy, whereas empathic emotions were related to right medial frontal atrophy. Findings suggest that bvFTD causes multiple types of breakdown in empathy, social cognition, and executive resources, mediated by frontal and temporal disease.

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.