ABSTRACT NUMBER: ESOC2026A1397 COGNITIVE AND NEUROIMAGING PROFILE OF SPORADIC CEREBRAL AMYLOID ANGIOPATHY PATIENTS WITH PHOSPHORYLATED TAU POSITIVITY

Abstract Background and aims Phosphorylated tau (pTau) in cerebrospinal fluid is a hallmark biomarker of Alzheimer’s disease (AD); however, its significance as a marker of AD co-pathology in sporadic cerebral amyloid angiopathy (CAA) remains unclear. This study aimed to characterize the cognitive and neuroimaging profile of pTau-positive CAA patients (CAApT+). Methods In this retrospective bicentric study, cognitive and neuroimaging profile were compared between CAApT+ patients and: a) pTau-negative CAA patients (CAApT-); b) AD controls matched for age and sex. Neuropsychological assessment evaluated processing speed, cognitive flexibility, language, verbal and visual memory, and visuoconstruction. Neuroimaging assessment included MRI markers of cerebral small vessel disease (SVD) and entorhinal cortex atrophy using ERICA score. Results Among 83 CAA patients (45 CAApT+, 38 CAApT−) and 42 AD controls, CAApT+ showed less global cognitive impairment than AD (69.2% vs 91.7%, p=0.03) but a similar prevalence than CAApT-. Compared with CAApT−, CAApT+ had poorer naming performance (21.1% vs 47.7%, p=0.02). In contrast, CAApT+ showed markedly better visual and verbal memory than AD patients (49% vs 81%, p=0.003 and 54% vs 89%, p=0.006 respectively). ERICA scores were significantly lower in CAApT+ compared with AD but did not differ between CAApT+ and CAApT−. SVD MRI biomarkers did not differ between CAApT+ and CAApT−. Findings were confirmed in multivariate analyses. Conclusions In our study, CAApT+ showed cognitive and neuroimaging features relatively similar to CAApT- but distinct from AD. These findings might suggest that pTau positivity in CAA may not solely reflect concomitant AD co-pathology. Conflict of interest AMAR: nothing to disclose