Executive function, processing speed and working memory as mediators of age-related decline in verbal memory encoding and retrieval processes.

摘要

The decline of memory with age is a well-established phenomenon. The purpose of this dissertation is to elucidate the mechanisms through which age exerts its effects on memory performance. The relative contributions of executive function, processing speed and working memory in age-related decline of verbal declarative memory have rarely been examined together, nor have their relationships with one another been fully explored as they pertain to age-related memory decline. Thus, taking each potential mediating variable into consideration, the present research seeks to test the empirical accuracy of an integrative, neuropsychological model of the cognitive aging process with respect to the two most basic memory processes---memory encoding and retrieval. All variables were measured using standard neuropsychological tests with a sample of 304 normal healthy older adults ranging from 54 to 92 years in age. Structural equation modeling indicated that much of the variance in cognitive performance among the mediators appeared to be shared. This is discussed in the context of the common cause hypothesis of age-related cognitive decline and in the context of suggestions for future research.