Anomia for people names in DAT--evidence for semantic and post-semantic impairments

Proper name anomia is a frequent finding among patients in the early stages of Alzheimer's disease. The present study investigates naming of famous persons in a group of DAT patients, a group of persons with mild cognitive impairment (MCI) and healthy controls. The study is aimed at distinguishing the relative contributions of semantic and post-semantic factors to difficulties in proper name retrieval. As shown by a significantly lower score in answering semantic questions, DAT patients retrieve less biographical knowledge related to famous persons than healthy elderly subjects and persons with mild cognitive impairment. This finding is in line with the frequent observation of semantic deficits in early and moderate DAT. The high number of Tip-of-the-Tongue (TOT) answers in DAT found in relation to few spontaneously named items shows that post-semantic deficits are as important as semantic deficits in determining anomia for people names in DAT. Moreover, DAT patients were less sensitive to phonological cueing than healthy persons or persons with mild cognitive impairment. These findings suggest that proper name anomia in DAT is not only due to semantic deficits, but also to problems in accessing the phonological representation, as well as to a degradation of phonological representations. Thus, naming deficits in DAT differ not only quantitatively, but also qualitatively from the difficulties of healthy elderly persons. No significant differences were found between persons with mild cognitive impairment and healthy controls in proper name retrieval.