Association of White Matter Hyperintensities, Regional Brain Glucose Metabolism, and Cognitive Impairment in Aβ-Negative Patients.

BACKGROUND AND

OBJECTIVES

Periventricular white matter hyperintensities (PWMHs) and regional brain glucose hypometabolism have each been linked to cognitive impairment, but their interplay independent of β-amyloid (Aβ) is unclear. This study examines whether PWMHs relate to region-specific cortical hypometabolism and metabolism mediates domain-specific cognition in Aβ-negative individuals.

METHODS

This retrospective cross-sectional study included 141 Aβ-negative patients with mild cognitive impairment (MCI) older than 50 years and 83 normal controls (NCs). All participants underwent 18F-fluorodeoxyglucose (FDG) PET, MRI and cognitive testing assessments at Severance Hospital, Yonsei University, between 2017 and 2022. PWMHs were defined as WMHs within 10 mm of the lateral ventricles; regional FDG standardized uptake value ratios were extracted from predefined cortical and limbic regions. Associations among PWMHs, metabolism, and cognition were tested using general linear models, and path analyses were conducted.

RESULTS

The MCI and NC groups did not differ in age or sex. Greater PWMH burden correlated with lower FDG uptake, strongest in the posterior cingulate cortex (PCC) (β = -0.14; 95% CI -0.20 to -0.09; q < 0.001). PWMHs were related to lower executive (β = -0.41; 95% CI -0.74 to -0.08; q = 0.026), verbal memory (β = -0.73; 95% CI -1.16 to -0.30; q = 0.005), and visual memory (β = -0.62; 95% CI -1.01 to -0.23; q = 0.005) scores. Path analyses indicated indirect effects of PWMHs on executive function through hypometabolism in the frontal lobe (indirect β = -0.06; 95% CI -0.13 to -0.01; p = 0.016) and PCC (β = -0.12; 95% CI -0.20 to -0.04; p = 0.003), whereas direct effects were identified for verbal (β = -0.27; 95% CI -0.45 to -0.08; p = 0.006) and visual (β = -0.24; 95% CI -0.41 to -0.08; p = 0.005) memory.

DISCUSSION: The effect of PWMHs on executive dysfunction was mediated by cortical hypometabolism, whereas memory dysfunction was directly driven by PWMHs. These findings suggest that incorporating 18F-FDG PET with MRI may enhance diagnostic and therapeutic stratification in clinical trials for vascular cognitive impairment.