Longitudinal Changes in Memory Performance and Processing Speed in Old Age abstract Keywords

The speed theory of cognitive aging posits that an age-related slowing of processing speed leads to impairments in higher order cognitive functions, such as memory. However, only few studies have examined the relationship between longitudinal changes in processing speed and longitudinal changes in memory performance. In the present study, data of 474 older adults (T1: 59–65 years) from the Interdisciplinary Longitudinal Study on Adult Development (ILSE) were used to investigate whether changes in speed and in memory were associated over a 4-year period. Performance changes in both constructs were analyzed using latent change factor models. Results show that latent changes in processing speed and latent changes in memory performance correlated with 0.61. This association is considerably lower than what would have been expected from cross-sectional data. Our longitudinal results suggest that although speed changes explain a substantial proportion of variance in memory changes, additional explanatory factors must be taken into consideration.