Semantic memory evolution in childhood vs its involution in Alzheimer disease Patients.

Semantic memory evolution in childhood vs its involution in Alzheimer disease Patients
According to the retrogenesis hypothesis, the comparison of cognitive functioning between children and Alzheimer's disease patients (AD) shows an inverse evolution pattern. The purpose of this research is to contribute to a better comprehension of semantic memory by comparing its evolution in childhood and its involution in Alzheimer disease patients. We particularly focus on thematic and taxonomic links between concepts. Indeed, these two kinds of links are predominant in the development of lexico-semantic concepts in children and always play an important role in adult structure.
In the first study, the performances of 40 Alzheimer patients and 20 healthy elderly controls in two 1-minute fluency task (category animals and letter P) and a 24 picture naming task are analysed. Alzheimer patients generated more errors and fewer words than elderly in the three tasks. Their productions in the fluency tasks were also earlier acquired and more frequent. The same work is about to begin with 60 children, to know if similar processes occur in reverse in patients and in children.
In the second study, we create a unique experimental paradigm adapted to children and Alzheimer's disease patients with a semantic knowledge questionnaire, a naming priming paradigm, a semantic pictorial sorting task and a verbal association task. Experiments are now in progress. The results obtained in Alzheimer's disease patients will be presented.
Errors, difficulties, reaction time and use of thematic and taxonomic links by patients in the two studies will give valuable information about semantic networks and research strategies.