👤 William Robert Kwapong

Dementia with Lewy bodies (DLB) frequently coexists with cerebrovascular injury and Alzheimer's-related pathology, yet accessible in vivo markers of these processes remain limited. The retinal microvasculature shares structural and physiological characteristics with cerebral small vessels and may provide a non-invasive window into neurovascular and neurodegenerative pathology. In this cross-sectional study, 32 individuals with DLB and 31 age-matched cognitively unimpaired controls (CU) underwent swept-source optical coherence tomography angiography (OCTA), brain MRI, and plasma biomarker assessment. Retinal vessel densities of the superficial vascular complex (SVC), deep vascular complex (DVC), and choriocapillaris (CC) were quantified. Plasma amyloid-β, phosphorylated tau-217 (p-tau217), and glial fibrillary acidic protein were measured. Cerebral small vessel disease (SVD) burden and white matter hyperintensity (WMH) volumes were derived from MRI. Associations with cognition and mediation by WMH burden were evaluated using generalized estimating equations and bootstrapped mediation analyses. Compared with CU, individuals with DLB exhibited significantly reduced SVC, DVC, and CC vessel densities (all p < 0.001). Lower retinal vessel densities were associated with higher plasma amyloid burden and elevated p-tau217, as well as greater SVD burden and periventricular WMH volume. APOE ε4 carriers demonstrated more pronounced retinal microvascular impairment, higher WMH burden, and elevated p-tau217 levels than non-carriers. Reduced SVC density was associated with worse global cognition, and this relationship was partially mediated by periventricular WMH volume. Retinal microvascular impairment measured by OCTA is closely linked to Alzheimer's-related plasma biomarkers, SVD, and cognitive decline in DLB. These findings support retinal OCTA as a scalable, non-invasive biomarker reflecting convergent neurodegenerative and vascular pathology in DLB. Show less

Apolipoprotein E (APOE) ε4 is the strongest genetic risk factor for Alzheimer's disease (AD), with homozygous carriers (ε4/ε4) experiencing accelerated cognitive decline. While its role in amyloid and tau pathology is established, its impact on retinal and cerebral microvasculature remains underexplored. A total of 107 AD (46 non-carriers, 42 heterozygotes, 19 homozygotes) underwent optical coherence tomography angiography (OCTA) to assess retinal microvasculature and magnetic resonance imaging (MRI) -derived peak width of skeletonized mean diffusivity (PSMD) to evaluate cerebral small vessel disease. Plasma biomarkers (Aβ Homozygous APOE ε4 carriers exhibited the most severe reduction in retinal microvascular density and higher PSMD (p < 0.001). Superficial retinal vessels and PSMD partially mediated APOE ε4's association with cognitive impairment. APOE ε4 homozygosity exacerbates retinal and cerebral microvascular dysfunction, which partially mediates cognitive impairment in AD. Apolipoprotein E (APOE) ε4 homozygosity is associated with the most severe reductions in retinal microvascular densities and elevated cerebral small vessel disease (peak width of skeletonized mean diffusivity [PSMD]) in Alzheimer's disease (AD). Vascular dysfunction (retinal and cerebral) correlates with lower Aβ42, higher p-tau217/Aβ Show less