Validation of a new tool to investigate multimodal lexical-semantic deterioration in Alzheimer’s disease: the multimodal semantic knowledge assessment (EMCS)

While episodic memory impairment is the most recognized initial symptom of Alzheimer’s disease (AD), semantic memory breakdown is also an early specific feature of the disease. This phenomenon notably results into lexical-semantic disorders affecting words retrieval and their meaning in all modalities (visual, auditory, tactile, olfactory, taste). However, there are still few tools in French to assess semantic deficit through all modalities. Our research aims to normalize a French multimodal semantic assessment battery called EMCS (Basaglia-Pappas et al., 2021). The battery is composed of 10 tasks, split into three input modalities (pictorial, written words, and sensorial). The EMCS has been administrated to 30 healthy elderly controls (HC). To study the sensibility and specificity of the battery, 25 AD patients in the early stage of the disease underwent the EMCS battery. Normative data were established through statistical analysis with percentile scores. We compared the AD group’s mean of each task to the percentile score of the HC group. Results highlight that the AD group is under the 5th percentile for each task, except for semantic association (Pc 10-25), tactile and auditory modality (Pc 5-10) tasks. The Receiver Operating Characteristic (ROC) analysis established the optimal cut-off score of the EMCS at 60.2 (sensitivity 96 %, specificity 100 %), differentiating AD patients to HC participants. EMCS can contribute to detect lexical-semantic disorders between HC and AD participants with a high specificity and sensibility. In clinical setting, assessment of semantic memory across all modalities may help clinical diagnosis and better define the therapeutic project.