The role of inhibitory function in associative memory among older adults and its plasticity

Associative memory deteriorates with age. One possible reason for this associative memory deficit in older adults is a decline in inhibitory function. However, it remains unclear what role of inhibitory function plays in age-related associative memory deficits, and whether and how acute training of inhibitory function could ameliorate the detrimental effects of inhibitory deficits on associative memory in older adults. In Experiment 1, 80 participants (40 younger and 40 older adults) studied scene-word pairs while attempting to inhibit interfering words during encoding, with two conditions: gist and non-gist interferences. In Experiment 2, 66 older adults were randomly assigned to either acute inhibitory training or a control group, and eye-tracking technology was used to capture the benefits of acute inhibitory training. Results showed that older adults were more disturbed by gist than non-gist interferences because of hyper-binding, and that inhibitory function mediated the relationship between age and associative memory accuracy. Notably, although acute inhibitory training did not significantly improve associative memory accuracy in the training group compared to the control group, structural equation model showed that older adults in the acute training group showed shorter fixation durations and lower frequencies in the interference region of interest, leading to better associative memory. These results indicate that inhibitory function plays a mediating role in age-related associative memory decline, as well as its plasticity in this association. It provides a potential pathway to improve associative memory in older adults.