Silent yet impaired: Hidden memory processing deficits in asymptomatic individuals with moderate‐to‐severe white matter hyperintensities

INTRODUCTION: White matter hyperintensities (WMHs) are strongly associated with cognitive decline and dementia, but whether asymptomatic individuals with moderate-to-severe WMHs (msWMHs) are truly cognitively intact, particularly in visual short-term memory (VSTM), remains unclear. METHODS: Electroencephalography and diffusion tensor imaging (DTI) was obtained from 45 msWMH patients and 38 normal controls during an occluded-face delay-matching task. RESULTS: Individuals with msWMH showed systematic deficits in face-memory processing across encoding, maintenance, and retrieval, accompanied by reduced theta power and synchronization, altered alpha power, and disrupted theta-gamma coupling. DTI further revealed microstructural damage, particularly in the inferior fronto-occipital fasciculus (IFOF), superior longitudinal fasciculus (SLF), and inferior longitudinal fasciculus (ILF), which mediated the effects on global cognition via encoding-related theta oscillations. DISCUSSION: These findings indicate that individuals with msWMH already show hidden VSTM deficits. Theta oscillations mediate the link between tract integrity and global cognition, highlighting a potential preclinical intervention target. HIGHLIGHTS: Asymptomatic individuals with moderate-to-severe white matter hyperintensities (msWMHs) already show visual short-term memory (VSTM) deficits. Electroencephalography revealed abnormal neural oscillations during encoding, maintenance, and retrieval stages. Damage to the inferior fronto-occipital fasciculus (IFOF), superior longitudinal fasciculus (SLF), and inferior longitudinal fasciculus (ILF) affects cognition via theta oscillations. Theta activity mediates structure - function coupling and may serve as a preclinical intervention target.