The executive functioning in normal aging: Impact of the cognitive reserve

There exists a large inter-individual variability regarding the effects of aging on cognition. According to Stern (2009), people who developed a high level of reserve are more resilient to the effects of aging that individuals with lower cognitive reserve. In this study, we describe the impact of cognitive reserve on executive functions in normal aging. Ninety healthy participants aged from 60 to 80 years were recruited. We assessed the three major executive functions: Inhibition (Stroop test, Hayling test, TAP Incompatibility subtest), Shifting (TAP Flexibility subtest, Plus-Minus task), and Updating (Letter-Number Sequencing subtest from MEM III, Letter memory task, 2-back task). Cognitive reserve was measured by questionnaires assessing educational level, occupation, leisure activities and physical activity across the life. Multiple linear regressions (p<0.05) adjusted for age, quality of sleep, processing speed showed that elderly with a high level of reserve have better performance on updating. We also assessed the effect of each factor of cognitive reserve separately after adjustment for the other. We observed that people with high level of education have better performance on flexibility (TAP Flexibility subtest and composite score) and on updating (Letter-Number Sequencing subtest, Letter memory and composite score). However, we didn’t observe any significant effect of the other factors of cognitive reserve. These results suggest that the cognitive reserve is related to abilities in some executive tests.