[Semantic knowledge in MCI and Alzheimer's disease: the French version of the New Words Interview].

INTRODUCTION

The first decline in cognitive performance in Alzheimer's disease can appear when assessing semantic memory and can be detected long before the typical symptoms of Alzheimer's disease (AD), appearing with Mild Cognitive Impairment (MCI).

PATIENTS AND METHOD

We propose the French version of the New Words Interview (fNWI) using 22 words to investigate semantic knowledge. The fNWI uses 11 words, which entered the French dictionary between 1996 and 1997, and 11 other words, which entered between 2006 and 2007. Words were paired according to orthographic and semantic criteria. Each word was associated with three sub-tests: free evocation, discrimination of the best definition from three propositions, and recognition of the accurate word context (two sentences were proposed). Regarding evocation, we distinguished conceptual definition, life situation examples or examples by use. We tested 12 patients with AD, 12 patients with amnesic Mild Cognitive Impairment (aMCI) and 72 controls (12 were paired with patients for age and education level).

RESULTS

MCI patients and AD patients exhibited lower performance than controls in the three sub-tests and for the words of both periods. From the early stage of MCI, the patients were more impaired in the fNWI than in the context recognition task, and they failed to provide conceptual definitions of new words. Therefore, MCI patients suffer from semantic impairments before obvious clinical signs of AD.

CONCLUSION

In patients with AD, performance worsened on all subtests, and more strongly in the definition discrimination task, which suggests the impairment of stored semantic knowledge. They provided fewer conceptual definitions and failed to use the strategy observed in MCI patients, who compensated for conceptual difficulties by providing examples.