P3‐476: Reduced Locus Coeruleus Integrity Is Associated With Poor Attentional Control in Older Adults Without Dementia
Year: 2019
Type: article
Study design: Observational Study
Abstract: Stroop test performance declines in pathologic aging, and reaction time intraindividual variability (RT-IIV) on this task may be a sensitive marker of preclinical Alzheimer's disease (AD) as higher IIV connotes a subtle breakdown in attentional control. The locus coeruleus (LC) noradrenergic system has been implicated in attentional processes and may be especially relevant for inhibition of goal-irrelevant stimuli during the Stroop task. As research implicates the LC as the earliest site of pathologic tau accumulation in preclinical AD, we examined associations between LC integrity and Stroop performance in older adults. 20 older adults without dementia were assessed. MRI markers of LC integrity were obtained using T1 FSE optimized to detect neuromelanin. Bilateral rostral LC signal intensities were standardized against the pontine tegmentum and averaged to derive an LC contrast ratio (LC-CR), where higher values indicate greater LC integrity. RT during a computerized Stroop task was averaged within each condition for all correct trials. Stroop effect was calculated as mean RT for incongruent minus congruent trials. Coefficient of variation (COV) was calculated as RT standard deviation/RT mean, collapsed across conditions. Iterated re-weighted least squares (i.e., “robust”) regression tested for associations between LC-CR and Stroop RT measures while controlling for age. Results showed expected RT slowing from congruent to neutral to incongruent conditions (Fig. 1). Stroop COV was significantly associated with LC-CR (r = −.50, t = −2.29, p = .01; Fig. 2A), such that higher RT-IIV across conditions (i.e., poorer attentional control) predicted reduced LC integrity. Stroop effect was not significantly associated with LC-CR, although a moderate effect size was observed (r = −.31, t = −1.41, p = .18; Fig. 2B).
Source: Alzheimer s & Dementia
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2980401726