This application describes a 3-year training plan that will enable me, a psychologist with a background in emotion and decision-making, to initiate cognitive neuroscience research on decision-making in older adults. Supervised by experts in neuroeconomics (Dr. Kable) and episodic memory and aging (Dr. Wolk), this proposal examines how episodic memory contributes to intertemporal choice, focusing on a population with substantial variability in episodic memory decline: older adults with and without preclinical levels of Alzheimer's disease (AD) pathology. When making choices between outcomes realized at different times (intertemporal choices), people prefer rewards sooner rather than later, often even when the delayed reward is larger. This tendency, temporal discounting, varies widely across individuals and contexts. Determining the neural mechanisms that underlie intertemporal preferences is important because overly myopic choices can be detrimental to people's health and well-being. The proposed experiments aim to address two major gaps in the literature on temporal discounting. First, research on intertemporal choice in older adults has yielded inconsistent results, suggesting that variability in cognitive decline among older adults may contribute to variability in these preferences and/or that the presence of preclinical levels of AD pathology, often unaccounted for in studies of aging, may influence this decision process. Second, there is evidence that the episodic memory system plays a role in promoting more patient choice, but the mechanism by which this occurs is unclear. Given the evidence of episodic memory decline in older adults, this proposal is well- positioned to tackle both of these questions.
The first aim i s to measure neuroanatomical and behavioral correlates of episodic memory and relate these to temporal discounting in a large sample of primarily older adults. Neuroanatomical correlates will comprise: gray matter volume in medial temporal lobe (MTL), tissue density in MTL, and white matter tract integrity between MTL and ventromedial prefrontal cortex. Behavioral correlates include vividness of episodic memory recall, assessed with the Autobiographical Memory Interview. In the same dataset, the second aim compares temporal discounting between the subset of older adults with preclinical AD (20-30%; assessed with amyloid PET imaging) and those without it. Since pathological substrates of AD include critical nodes of the memory network, we expect that differences in temporal discounting between these groups might be mediated by MTL structure differences.
The third aim manipulates episodic memory prior to intertemporal choice in middle-aged and older adults and investigates (using fMRI) the neural mechanism by which memory retrieval impacts choice. We expect that retrieving positive autobiographical memories will reduce temporal discounting, most likely through interactions between episodic memory and valuation regions. The proposed research will contribute to our understanding of the neural mechanisms underlying intertemporal choice, and it may inspire novel interventions for fostering patient choice.
Temporal discounting, the tendency to overvalue immediate rewards relative to delayed rewards, is associated with poor economic and health outcomes (e.g., obesity, addiction, debt). This research examines the relationship between behavioral and neural correlates of episodic memory and temporal discounting, by taking advantage of the variability in episodic memory decline observed in older adults. This work also investigates the effects of preclinical Alzheimer's disease pathology on temporal discounting, and tests a manipulation that might increase patience among adults of all ages.
