Contributions of Cognitive Aging Models to the Explanation of Source Memory Decline across the Adult Lifespan

Background: A number of cognitive aging models have been proposed to explain the age-related decline in several cognitive functions, but these models have rarely been examined together. We analyzed the contributions of four main models - processing resources, speed of processing, cognitive reserve and knowledge - to source memory decay related to the aging process. Methods: A total of 1554 healthy adults between 21 and 80 years old participated in the study. Structural equation modeling was conducted on data from the whole sample and separately in the data from young, middle-aged and older adult age groups. To estimate each cognitive model, we measured working memory discrimination levels (processing resources), working memory reaction times (speed of processing), education (cognitive reserve) and vocabulary (knowledge). Results: Processing resources mediate the effects of age on source memory across the adult lifespan, whereas speed of processing mediates these effects only in young adults, cognitive reserve only in middle-aged adults and knowledge only in older adults. Conclusions: Processing resources was the cognitive model that most contributes to explaining source memory decay. The fact that the other models are relevant to specific age groups provides useful information to exploit their benefits to preserve source memory in specific life stages.