Cognitive reserve counteracts typical neural activity changes related to ageing

Studies have shown that older adults with high Cognitive Reserve (HCR) exhibit better executive functioning than their low CR (LCR) counterparts. However, the neural processes linked to those differences are unclear. This study investigates (1) the neural processes underlying enhanced executive functions in older adults with HCR and (2) how executive control differences are modulated by task difficulty. We recruited 74 participants, who performed two executive control tasks with different difficulty levels while recording the electroencephalogram. The accuracy on both tasks requiring inhibition of irrelevant information was better in the HCR than the LCR group. Also, in the more demanding task, event-related potentials (ERP) latencies related to inhibition and working memory update were faster in HCR than LCR. Moreover, the HCR, but not the LCR, showed larger P300 amplitude in parietal than frontal regions and in the left than right hemisphere, suggesting a posterior to anterior shift of activity and loss of inter-hemispheric asymmetries in LCR participants. These results suggest that high CR counteracts neural activity changes related to ageing. Thus, high levels of CR can be related to maintenance of neural activity patterns typically observed in young adults rather than to deployment of neural compensatory mechanisms.