Education as a moderator of the relationship between episodic memory and amyloid load in normal aging

Résumé

The current study explored whether education, a proxy of cognitive reserve, modifies the association between episodic memory performance and βeta-amyloid load (Aβ), a biomarker of Alzheimer’s disease, in a cohort of cognitively normal elderly adults. One hundred and four participants (mean age 73.3 years) evenly spread out in three bands of education were recruited. Participants underwent neuropsychological assessment, structural MRI as well as PET imaging to quantify Aβ load. Moderation analyses and the Johnson-Neyman technique were carried out to examine the interaction of education with Aβ load to predict episodic memory performance. Linear regressions were then performed within each group of education to better illustrate the interaction effect (all analyses were controlled for age and sex). The interaction between education and Aβ load was significant (p<0.05) for years of education, reaching a cut-off point of 13.5 years, above which the relationship between Aβ load and episodic memory was no longer significant. Similarly, significant associations were found between Aβ and episodic memory among participants with secondary (p<0.01) and pre-university education (p<0.01), but not with a university degree (p=0.253). Episodic memory performance is associated with Aβ load in cognitively normal elderly individuals, and this relationship is moderated by educational attainment.