Semantic knowledge of newly coined words in mild cognitive impairment and Alzheimer’s disease

BackgroundMild Cognitive Impairment (MCI) patients at risk for developing Alzheimer’s disease frequently show subtle semantic memory deficits. The aim of this study is to investigate how early semantic impairments extend to words having recently entered the lexicon, in order to provide new clinical cues to discriminate between patients with MCI, AD and controls.MethodSemantic abilities of patients with AD (n = 12), amnestic MCI (n = 12) as well as healthy controls (n = 12) were measured with the New Word Questionnaire (NWQ), including 22 words that entered the French dictionary 2 or 12 years ago. The NWQ assesses the abilities (1) to give definitions for these words, (2) to decide which of three definitions is accurate, and (3) to choose which of two sentences containing the word is correct. Quantitative and qualitative analysis of responses were carried out by distinguishing conceptual definitions from operational definitions in terms of use and quotations from examples.ResultsPatients with MCI demonstrate lower performance than controls in the 3 tasks. Their pattern of performance is characterized by difficulties discriminating the accurate definition rather than selecting the correct context. This difference increases in patients with AD. In addition, patients with MCI often provide examples in order to compensate for their conceptual difficulties, whereas patients with AD fail to use this strategy. Finally, the transition to AD changes the pattern of correlations between performance in the NWQ, episodic memory, and executive functioning.ConclusionThe NWQ may be useful to characterize the cognitive profile associated with MCI and to assess AD conversion.

► An early decline in semantic function in MCI. ► MCI and AD patients had difficulty defining a word and recognizing its correct definition. ► An early deficit for the functional characteristics of the words in MCI and AD. ► Nevertheless, MCI patients provided more life situation example relative to controls. ► Abilities to define a word were correlated with episodic memory and executive functions.