A longitudinal event-related potentials study of idiom processing in healthy elderly adults

This study investigates the longitudinal effects of cognitive aging on elderly adults’ sentence processing. To this aim, 16 Dutch elderly adults who participated in a previous study on idiom processing were tested again three years later, using the same event-related potential (ERP) paradigm. Compared to the previous study, we found the same reduced N400 for idiomatic sentences and for sentences preceded by a predictive context, and the same increased P600 for literal sentences preceded by a predictive context. However, the general N400 effect decreased over time, whereas the general P600 effect increased over time. Our findings suggest that elderly adults’ ability to benefit from context information and the fixed character of idioms to facilitate sentence processing is preserved over time. However, the longitudinal changes in the N400 and P600 effect suggest that elderly adults adopt alternative processing strategies to compensate for age-related cognitive decline.