Locus Coeruleus Impact on Memory Variability in Older Adults

Poster Session A - Saturday, April 13, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Kitzia Solis¹, Jason Langley¹, Andrew Sun², Aaron Seitz², Xiaoping Hu¹, Ilana Bennett¹; ¹University of California, Riverside, ²Northeastern University

The locus coeruleus (LC) is the primary source of norepinephrine (NE) in the brain and has been linked to cognitive processes such as attention and memory, which decline with age. NE plays a key role in arousal, therefore dysregulation of the LC-NE circuit may result in disrupted attention, which has been shown to negatively affect working memory performance (Unsworth & Robison, 2017). Disrupted attention could also influence variability in memory performance, which has not yet been examined. To address this gap, the present study examined the impact of LC structural integrity on memory variability in healthy older adults (n=55; 60-85 years). Participants completed a magnetic resonance imaging (MRI) session, with a neuromelanin sequence to estimate signal intensity in the LC, and a diffusion-weighted sequence from which multi-compartment diffusion metrics (intracellular, free) were obtained from the LC. Participants also completed a free recall task involving three distinct wordlists, each comprising 10 unique words, from which average recall and variability across the 3 trials was calculated. Our analyses revealed that there were no effects of age or sex on recall performance. However, higher intracellular diffusion in the LC related to less variability in recall, but not to average recall. LC signal intensity and free diffusion did not relate to recall performance. These findings are consistent with the notion that memory variability is more sensitive to LC-NE attentional lapses than average memory performance, and that LC diffusion is more sensitive than the more commonly used signal intensity metric.

Topic Area: ATTENTION: Development & aging