Exploring the Role of Attentional Control in Delirium and Dementia

The National Institutes of Health’s National Institute on Aging has awarded Duke Anesthesiology’s Leah Acker, MD, PhD, a five-year $3,820,100 R01 grant for her project, “Attentional Resilience in Older Adults.” The study will introduce the concept of attentional resilience—the brain’s ability to preserve cognitive performance by efficiently reallocating limited neural resources during physiological stress—and will evaluate its potential underlying mechanisms using scheduled surgery in cognitively healthy older adults as a “natural experiment.”

In delirium and Alzheimer’s disease (AD), which increase the risk for each other, patients suffer deficits in executive functions, including attentional control. There is a critical gap in our understanding of the mechanisms by which attentional control capacity may promote cognitive resilience in both delirium and dementia. Even under normal conditions, neural resources for navigating the world around us are fundamentally limited (ie, we can’t attend to everything in our environment), yet attentional control allows the brain to effectively allocate neural resources to accomplish cognitive tasks. Strong attentional control can protect cognitive function when the brain is injured and inflamed, which makes attentional control a potentially powerful tool for reducing the incidence and impact of delirium and dementia.

The overall objective of Acker’s research is to better understand the neural mechanisms underlying attentional resilience, which enable individuals to more effectively allocate neural resources, and thus, to remain attentive to their surrounding environment despite neuronal injury and/or neuro-inflammation. The central hypothesis is that neural mechanisms underlying robust attentional control before surgery facilitate attentional resilience after surgery.

Acker’s research aims will evaluate brain activity patterns that have been linked to robust attentional control and their relationship to sensory processing, a mechanism by which the brain enhances its electrical response to relevant sensory stimuli. The aims specifically include 1) evaluating the relative contributions of “bottom-up” sensory stimulation and “top-down” attentional preparation to pre-op brain activity patterns that predict attentional resilience, 2) exploring how neural signatures of general “attentiveness” enhance pre-conscious sensory processing thought to facilitate attentional resilience, and 3) determining how well-balanced brain circuits may contribute to attentional resilience. Because robust neural circuits depend on healthy neuronal substrates largely free from AD-related pathology, Acker will evaluate the effect of pre-clinical Alzheimer’s pathology on attentional resilience mediated by coordination between two complementary neural circuits critical for attentional control.

“This project will advance our understanding of why some older adults maintain strong attentional performance after surgery while others do not,” says Acker, assistant professor in anesthesiology. “In particular, our work will reveal key neural-systems-level mechanisms that support attentional control capacity and link low-level neuronal damage to diminished high-level cognitive performance. Long-term, we believe that our work will identify potentially modifiable neural targets for delirium and dementia interventions.”

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