Executive functions in normal aging: Impact of cognitive reserve and objective physical activity

It is now acknowledged that there exists a large inter-individual variability in age-related cognitive changes. According to Stern (2009), the cognitive reserve built up throughout the life span will make seniors more or less resilient to the deleterious effects of aging on cognition, with seniors having a high level of cognitive reserve being more prone to successfully cope with cognitive and neuronal changes. Currently, few studies have focused on the specific effects of different factors of cognitive reserve on cognition. Consequently, the objective of this study is to determine the impact of four determinants of cognitive reserve on executive functions in normal aging. Sixty-eight healthy participants aged 60 to 80 were enrolled. Regarding 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) were assessed (Miyake et al., 2000). Cognitive reserve was measured by questionnaires assessing educational level, occupation, leisure activities and physical activity. Moreover, an accelerometer allowed quantitative measure of physical activity by recording body movements during two weeks. Group comparisons (p<0.05) showed that seniors with a high level of cognitive reserve (measured by a global composite z-score) have better updating abilities (Letter memory task and updating composite score). In order to test the influence of each cognitive reserve factor on executive functions, simple linear regressions (p