Évaluation de l’effet de faux souvenirs en vieillissement normal : validation de scores composites des fonctions temporale médiane et frontale et contribution aux hypothèses théoriques

Aging is associated with many cognitive modifications, including a decline in the ability to memorize and/or recall events personally experienced. In parallel, it also causes an increase in false memories, which is the recall of an event that did not actually happen. False memories can have important consequences in the daily life of elderly persons and it is thus very important to better understand this phenomena in normal aging.  Some studies demonstrated the critical role of medial temporal lobe functions (MTL)/memory and frontal lobe functions (FL)/executive functions in the explanation of false memories. Thus, the goal of the first study was to validate a French and adapted version of the Glisky, Polster, & Routhieaux, (1995) methodology used to assess those cognitive functions (Chapter 2). A factorial analysis showed that neuropsychological scores associated with memory loaded onto one factor, the MTL/memory factor, while neuropsychological scores associated with executive functioning loaded onto a second factor, the FL/executive functions factor. Bootstrap analyses with a 1,000 re-samples showed stability for the majority of the scores in the original factor analysis. The goal of the second study was to examine the theoretical hypothesis and cognitive mechanisms (MTL/memory function and FL/executive functions) underlying the increase false memory effect in healthy aging, compared to young adults (Chapter 3). The Fuzzy Trace Theory (FTT; Brainerd & Reyna, 1990) proposes greater implication of MTL/memory function, whereas the Activation/Monitoring Framework (AMF; Roediger, Balota, et al., 2001) proposes greater implication of FL/executive functions as a theoretical explanation of false memory in aging. Fifty two older adults (mean age of 67.81 years) were tested with the neuropsychological tests associated with MTL/memory and scores associated with FL/executive functions. Based on the previous validation study, MTL/memory composite score and FL/executive functions composite score were calculated for each participant. Older adults were first categorized as high (n = 29, mean age of 67.45 years) or low on the MTL/memory function’s score (n = 23, mean age of 68.26 years) with careful statistical control of confounding variables, such as the FL/executives functions score. They were then categorized as high (n = 26, mean age of 68.08 years) or low (n = 25, mean age of 67.36 years) on the FL/executive functions’ score with the statistical control of confounding variables, such as the MTL/memory score. Proportions of true and false memory (targets and critical lures) were measured with a Deese-Roediger and McDermott paradigm (DRM; Deese, 1959; Roediger & McDermott, 1995), with free recall and recognition with « Remember / Know » judgments (Tulving, 1985) and were acquired for the 52 older adults and in 22 young adults (mean age of 24.59 years), matched for years of education. These proportions were compared across young adults and the two subgroups of older adults categorized on the MTL/memory function score in order to test the FTT hypothesis. Then, these proportions were compared across young adults and the two subgroups of older adults categorized on the FL/executive functions score in order to test the AMF hypothesis. Importantly, this is the first study to directly compare these hypothesis with numerous true and false memory measures. Results showed that MTL/memory function uniquely modulated the differences in age effects in DRM true memory, and in a more indirect way, in false memory and the relation between true and false recollection. Furthermore, results showed that only FL/executive functions played a role in false recognition of critical lures. Moreover, age effects in false recall and in false recollection were always observed between young adults and high performing older adults, regardless of the cognitive function studied. This finding suggests that factors other than MTL/memory and FL/executive functions need to be identified in order to better understand the increased vulnerability of false memory in older adults. Results are discussed in light of theoretical and cognitive hypotheses of false memory (Chapter 4).

Keyphrases: Cognition, Aging, Normal aging, False memory, Neuropsychology, Cognition, Episodic memory, Memory function, Executive functions, Medial temporal function, Frontal function