This chapter reviews major theories of cognitive aging. Theories such as the sensory deficit hypothesis, speed of processing, and inhibitory deficit hypothesis are based largely on behavioral findings and focus on a single process that is purported to account for a number of cognitive changes with age. Specific to memory, theories focus on age deficits in recollection and binding. Over the past twenty-five years, brain-based models have begun to pervade the literature. These have focused on concepts such as compensation, dedifferentiation, and suppression of the default mode network. The scaffolding theory of aging and cognition integrates many of these concepts into a single comprehensive model, including consideration of enrichment and depletion factors that operate over the life span. We conclude the chapter with some debates, critiques, and consideration of future directions, particularly considering the contributions of cognitive neuroscience methods.

Age-related changes in memory are a common but worrisome occurrence in many people’s lives. However, these changes are not ubiquitous. Healthy aging appears to impact memory for associative/relational details, i.e., the ability to recollect, more so than memory for item information. We propose that alterations in the recruitment of prefrontally mediated cognitive control processes, such as strategy use and inhibitory control, underlie these age-related memory deficits in healthy adults. These processes are particularly critical for remembering specific relational details and for being able to resolve interference between competing memories. Critically, evidence suggests that while there are large individual differences in the impact of aging on memory, various methods of support/intervention can improve memory performance in healthy older adults. We discuss how recent developments in neuroscience analysis methods have enhanced our understanding of how aging affects the control processes that support episodic learning and retrieval. We further suggest that future studies should test more diverse samples of adults and assess the role of lifestyle factors on individual differences in patterns of episodic memory performance and supporting brain activity and structure.