L’atteinte des processus d’encodage et de consolidation en mémoire épisodique est précoce dans le syndrome démentiel de type Alzheimer. Or, il existe peu d’outils diagnostiques adaptés aux personnes âgées, en termes de facilité d’administration et de données normatives.

Le but de cette étude était de développer une tâche évaluant la mémoire épisodique verbale chez les personnes âgées de 70 à 89ans.

La tâche (GERIA-12) est basée sur la même procédure que l’épreuve de rappel libre/rappel indicé à 16 items mais ne comporte que 12 items et 2 essais d’apprentissage. Afin d’évaluer les processus de consolidation, des rappels différés ont lieu après 20minutes et 24h. L’étalonnage a porté sur 220 personnes âgées de 70 à 89ans, issues de 3 niveaux de scolarité différents.

Les performances diminuent avec l’âge et augmentent avec le niveau scolaire. L’étalonnage a été effectué avec la méthode Barona pour les rappels libres, et sous forme de percentiles pour les rappels totaux, la reconnaissance et les indices (encodage, consolidation et récupération).

Cette tâche évalue les processus d’encodage, de stockage et de récupération, et dispose de données normatives précises et d’une procédure plus adaptée aux personnes âgées (facilité d’administration en consultation).

Early damage to episodic memory encoding and consolidation processes has been demonstrated in dementia of the Alzheimer type. However, in the domain of verbal episodic memory assessment, there are few diagnostic tools adapted to the old and oldest old as far as ease of administration and accuracy of normative data are concerned. Classic tasks are either too effortful (like the free recall/cued recall of 16 items), not sensitive enough (like the 5 words test), or insufficiently accurate for people above 70 years old in terms of normative data.

The aim of this study was to develop a reduced task (in terms of number of items and number of trials) assessing verbal episodic memory in people aged between 70 and 89 years old.

The task (GERIA-12) used the same procedure as the RL/RI-16 task but the list comprised only 12 words and there were only 2 learning trials. In order to assess consolidation processes, we included 2 delayed recall trials, one after 20minutes and the other after 24hours. We also calculated indexes adapted from the Item-Specific Deficit Approach developed by Wright et al., which has the advantage of providing measures specific to encoding, consolidation and retrieval processes. Standardization was done with data from 220 people aged between 70 and 89 years old and belonging to 3 education levels.

We obtained a significant effect of age and education level: scores decrease with age and increase with education. Norms have thus been calculated taking those two variables into consideration. Concerning the standardization, Barona method has been used for free recall scores while percentiles have been used for all other scores (total recall, free recall, encoding, consolidation and retrieval indexes). Normative data are also provided for intrusions and perseverations.

This new task allows encoding, consolidation and retrieval processes assessment in older people and has the following advantages: the procedure is more suitable (ease and time of administration), there are accurate normative data for old and oldest old people, and there are normative data for two delayed recalls (at 20minutes and at 24hours).