The congruence effect is impaired in healthy aging: a relationship to event-related potentials and theta-alpha oscillations

Long-term memory can improve when incoming information is congruent with known semantic information. This so-called congruence effect has widely been shown in younger adults but age-related changes and neural mechanisms remain unclear. Here, congruence improved recognition memory in younger and older adults (i.e. congruency effect), but textendash importantly textendash this effect decreased with age. Electroencephalography data show that, in both groups, congruence led to widespread differences in event-related potentials (ERPs) and alpha-beta oscillations (8-30 Hz), known to support semantic processing. Importantly, these ERP differences predicted increases in memory performance, especially for congruent items. Finally, age-related differences in memory were accompanied by a positive ERP and later decrease in theta-alpha (5-13 Hz) during encoding, which were greater in the younger group. Together, although semantic congruence generally increases long-term memory, the effect is less pronounced in the elderly. At the neural level, theta-alpha oscillations, previously linked to memory and attentional processes, provide a mechanistic explanation for such an age-related effect.