Dopaminergic and reward-related enhancement of memory in aging

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Claire J. Ciampa¹ (claireciampa@brandeis.edu), Thomas M. Morin^1,2, Jourdan H. Parent¹, Jordyn L. Cowan¹, Alex Adornato^1,2, Katherine O'Malley¹, Arielle Tambini³, Cristina Cusin², Jacob Hooker², Anne S. Berry¹; ¹Brandeis University, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, ³Nathan Kline Institute for Psychiatric Research

Age-related dopamine reductions are linked to declines in episodic memory and reward processing, making the dopamine system a key target for memory enhancement in aging. We investigate the independent and interactive effects of dopamine and reward on memory in a sample of 44 healthy older adults (mean age=69, range=60-82) who have undergone two fMRI scans (first on a placebo and second on 20mg oral methylphenidate to enhance dopamine availability). During each scan, participants completed an encoding task with alternating “high reward” blocks ($5/remembered item) and “low reward” blocks ($0.01/remembered item). A memory test 24 hours later assessed 1) item recognition, and 2) reward context of the items. We found that both reward and methylphenidate improved item memory, demonstrated by main effects of reward (p=.003) and drug (p=.02) on hit rate. While reward and methylphenidate did not enhance context memory, there was a trend toward better memory for high reward contexts (p=.09). Hippocampal fMRI activation was higher during high reward blocks compared with low reward blocks (p=.03), suggesting that the hippocampus may be more active while encoding high rewards. There was no effect of drug on hippocampal activation (p=.16), and no Reward*Drug interactions predicting hippocampal activation or memory. Finally, higher hippocampal activation related to better context memory (p=.02) but not item memory (p=.31), consistent with work showing that the hippocampus supports context encoding. These results demonstrate that enhanced dopamine and reward improve item memory in older adults, and that high reward relates to greater hippocampal activation, which supports better context memory.

Topic Area: LONG-TERM MEMORY: Development & aging