Locus coeruleus integrity is related to an exploitation-based decision-making bias in older adulthood

Abstract

Optimal decision-making balances exploration for new information against exploitation of known rewards, a process mediated by the locus coeruleus and its norepinephrine projections. We predicted that an exploitation-bias that emerges in older adulthood would be associated with lower microstructural integrity of the locus coeruleus. Leveraging in vivo histological methods from quantitative MRI-magnetic transfer saturation-we provide evidence that older age is associated with lower locus coeruleus integrity. Critically, we demonstrate that an exploitation bias in older adulthood, assessed with a foraging task, is sensitive and specific to lower locus coeruleus integrity. Because the locus coeruleus is uniquely vulnerable to Alzheimer's disease pathology, our findings suggest that aging, and a presymptomatic trajectory of Alzheimer's related decline, may fundamentally alter decision-making abilities in later life.

Keywords: MRI; aging; decision-making; human.

Fig. 1.

LC related to age and foraging behavior. (A) LC region of interest. (B) Lower LC MTsat, a measure of LC integrity, is associated with older age. (C) Lower LC MTsat is associated with greater exploitation, indexed by the leave time difference on the foraging task (lower LTD values reflect greater exploitation). p.u.: percent units.