Tip-of-the-tongue for proper names in non-amnestic mild cognitive impairment

Difficulty in recalling people's names is very common in the early stages of Alzheimer's disease and in mild cognitive impairment (MCI). Recent studies using tip-of-the-tongue (TOT) tasks have shown that impaired naming of famous people by amnestic MCI patients is associated with difficulties in accessing the phonological representations of the names, but not with semantic breakdown. The aims of the present study were to investigate, by use of a TOT task, semantic and phonological access to famous people's names in non-amnestic MCI and to test whether impairment in verbal episodic memory and other cognitive domains leads to difficulties in semantic and phonological access. We compared the performance of individuals with multiple domain amnestic MCI with that of individuals with multiple domain non-amnestic MCI and of healthy controls, and we studied the relationships between TOT production and the functioning of verbal episodic memory and other cognitive domains. In the multiple domain MCI groups (amnestic and non-amnestic), the main process affected was phonological access; failure in phonological access was related to deficits in general cognitive functioning and executive functioning. Semantic access was not impaired in either type of MCI. We interpret the findings in light of the transmission deficit hypothesis, as multiple domain MCI involves greater deficit in transmission from semantic to phonological representations than that produced by normal ageing, possibly because of reductions in cognitive resources and executive functions. (C) 2013 Elsevier Ltd. All rights reserved.