Isabelle Simoes Loureiro

Distinct progression of the deterioration of thematic and taxonomic links in natural and manufactured objects in Alzheimer's disease

Taxonomic and thematic relationships are core elements of lexico-semantic networks. However, the weight of both links differs in semantic memory, with distinct support for natural and manufactured objects: natural objects tend to be more taxonomically identified while manufactured objects benefit more from the underlying thematic relationships. Alzheimers disease (AD) causes early semantic memory impairment characterized by a category-specific deterioration, where natural objects are more sensitive to the disease than manufactured objects. However, relatively few studies have examined the progressive deterioration of specific thematic versus taxonomic relations in both categories of objects in AD. To better understand semantic memory disorganization in AD and analyze the potential interaction effect between the category (natural/manufactured), the condition (thematic/taxonomic) and AD, we will investigate the lexico-semantic network in 82 AD patients (divided into three groups depending on their global cognitive deterioration and their performance in a preliminary semantic knowledge questionnaire (mild (AD1), moderate (AD2) and advanced (AD3) stages of semantic knowledge alteration). The experimental protocol contains two tasks: an implicit semantic priming paradigm and an explicit card-sorting test that uses the same items, equally divided between natural and manufactured objects. Results show a distinct taxonomic and thematic evolution pattern with early taxonomic deterioration. Natural objects are also more vulnerable to the disease. Lastly, there is an interaction effect between the category and the condition in the priming task indicating that natural objects are more taxonomically organized and manufactured objects benefit more from both thematic and taxonomic organizations, reinforcing the idea of the robustness of this category. The theoretical accounts of these observations will be discussed in detail.

Le QCS : questionnaire de connaissances sémantiques pour déterminer le stade de détérioration sémantique chez les patients atteints de la maladie d’Alzheimer

Lexico-semantic difficulties are common in Alzheimers disease (AD). The bottom-up process theory is today well accepted: superordinate attributes tend to decline slower than subordinate ones. However, a specific issue in semantic memory investigation in AD is to determine the severity of the semantic impairment. Given that the regularity of the semantic disorder in early AD is uncertain, we argue that the constitution of experimental AD groups must consider the semantic deterioration stage. We thus propose a specific semantic knowledge questionnaire (SKQ), based on Laiacona et al.s work (1993). SKQ was proposed to 49 AD patients and 33 healthy old people. Three experimental AD groups were created, based on the global cognitive deterioration. In a second study, we explore the possibility for early AD to display different semantic deterioration profile. Our results show a significant group effect, a significant type of question effect (superordinate vs subordinate) and a significant interaction effect. Moreover, a significant correlation between the total errors at the SKQ and the MMSE score is observed. Finally, we observe that early AD patients can show different semantic alteration, with mild or very mild semantic deterioration without any differences in the global cognitive alteration. The SKQ seems adapted to highlight the semantic deterioration and the bottom-up process in AD: superordinate information are better preserved than subordinate information. It can also distinguish different semantic deterioration in early AD. Our result clearly show that research on semantic deterioration in early stage of AD must take into account the severity of the semantic alteration.

Étude des caractéristiques psychologiques et psychobiologiques des enfants à haut potentiel

Resume Cette etude a pour objectif de mettre en evidence les profils psychologiques et physiologiques des enfants a haut potentiel. En effet, certaines caracteristiques sont plus frequemment associees aux hautes potentialites (grossesses anormales, naissances prematurees, myopie, allergies, migraines...). Ces caracteristiques nous amenent a formuler l’existence de perturbations durant la grossesse ayant pour consequence le developpement d’une structure cerebrale singuliere, propre a ces enfants. Notre etude inclut 45 enfants a haut potentiel repartis dans 2 groupes selon l’harmonie de leur profil intellectuel et un groupe de 30 enfants a potentiel normal. Notre recherche confirme la presence de caracteristiques psychologiques, psychopathologiques, physiologiques et sociales des enfants a haut potentiel. L’origine innee ou acquise de ces perturbations n’est pas encore bien determinee. Notre option defend l’hypothese d’une influence combinee des facteurs environnementaux et innes dans le developpement de hautes potentialites chez l’enfant.

Échelle de communication fonctionnelle globale pour patients atteints de maladie neurodégénérative (ECMN)

Verbal and nonverbal communication impairments are often observed in the context of neurodegenerative diseases. Identifying the most appropriate communication strategies for each patient, by a better understanding of his communicational difficulties, would help to maintain his autonomy and to improve his quality of life. OBJECTIVE To propose a rapid and ecological tool specifically adapted for people with cognitive disorders in advanced stages of the diseases. METHODS Two major steps were necessary, the development of the tool itself (A) and the evaluation of some of its psychometric properties (B). The first step (A) allowed the development of a tool aimed at the observation of communication skills during a situation of natural interaction and the analysis of communication according to various activities (production, recognition and comprehension of oral language acts, written and gestural, as well as figures, in different degrees of complexity). The second step (B) consisted to measure the validity of the content and the criterion of the test, as well as its fidelity between judges. The final version of the tool is composed of two grids, an examiners guide and a patients test sheet. The use of the tool has been standardized. RESULTS At the end of the validation process, psychometric properties demonstrated good content validity and good criterion validity for the scale. Fidelity was subsequently measured and also judged to be good. After that, a pre-test with patients with neurodegenerative diseases has been carried out. CONCLUSION This tool should address a significant clinical need to enable clinicians to rapidly describe communication skills in a patient with neurodegenerative disease and to recommend communication strategies for formal and informal caregivers.

Impact of Auditory-Visual Bimodality on Lexical Retrieval in Alzheimer's Disease Patients

The aim of this study was to generalize the positive impact of auditory-visual bimodality on lexical retrieval in Alzheimers disease (AD) patients. In practice, the naming skills of healthy elderly persons improve when additional sensory signals are included. The hypothesis of this study was that the same influence would be observable in AD patients. Sixty elderly patients separated into three groups (healthy subjects, stage 1 AD patients, and stage 2 AD patients) were tested with a battery of naming tasks comprising three different modalities: a visual modality, an auditory modality, and a visual and auditory modality (bimodality). Our results reveal the positive influence of bimodality on the accuracy with which bimodal items are named (when compared with unimodal items) and their latency (when compared with unimodal auditory items). These results suggest that multisensory enrichment can improve lexical retrieval in AD patients.