White Matter Damage Drives Cognitive Decline via Two Distinct Pathways

White matter hyperintensities are ubiquitous findings on brain magnetic resonance imaging in older adults that frequently signal underlying cerebral small vessel disease, a condition where the pooled prevalence of global cognitive impairment reaches 57% [1]. These lesions elevate the risk for stroke, cognitive decline, and mortality, with severe burdens strongly associated with vascular dementia (odds ratio 10.35) [2, 1]. In patients with mild cognitive impairment, a higher volume of these vascular lesions consistently correlates with worse cognitive performance, particularly in attention and executive functioning (effect size -0.26) [3]. Furthermore, longitudinal data indicate that white matter hyperintensity volume significantly increases the risk of progressing from normal cognition to mild cognitive impairment by 35% (relative risk 1.35) and to frank dementia by 49% (relative risk 1.49) [4]. While the link between structural white matter damage and cognitive impairment is well established, the exact mechanisms by which these vascular lesions disrupt downstream cortical networks remain incompletely understood. Recent findings now provide specific data on how regional white matter lesions interact with cortical glucose metabolism to drive distinct cognitive deficits in patients lacking the beta-amyloid pathology characteristic of Alzheimer disease.