ABSTRACT NUMBER: ESOC2026A1138 CLINICAL, NEUROIMAGING AND BIOMARKER FEATURES OF CEREBRAL AMYLOID ANGIOPATHY: DATA FROM THE NATIONWIDE ITALIAN SENECA REGISTRY

Abstract Background and aims Cerebral amyloid angiopathy (CAA) is a major cause of lobar intracerebral hemorrhage (ICH) and cognitive impairment in older adults, with frequent overlap with Alzheimer’s disease (AD). We aimed to describe the clinical spectrum, MRI features and biomarker profiles of patients enrolled in a nationwide Italian CAA registry. Methods SENECA is an observational, multicentre registry including consecutive patients with suspected or probable CAA recruited across 37 neurological centres in Italy (July 2023–February 2024). Demographic and clinical data, index clinical events, brain MRI features, CSF biomarkers (Aβ40, Aβ42, total tau, p-tau181), amyloid-PET and APOE genotype were collected when available. Results A total of 577 patients were included (median age 73 years [IQR 68–78], 54.4% men). Lobar ICH was the most frequent index event (56.3%), followed by cognitive impairment (11.3%) and seizures (7.6%). Seizures were more frequent in women (OR 2.0), while men experienced ICH at a younger age (β −3 years, P = 0.01). Results are summarized in Table 1. MRI data (92.2%) showed frequent overlap of haemorrhagic markers; cortical superficial siderosis was associated with transient focal neurological episodes (P = 0.001) and epilepsy (OR 1.78). CSF biomarkers (n = 84) showed a reduced Aβ42/40 ratio in 75% and an AD-like ATN profile in 50%. Amyloid-PET was positive in 85.0% of examined cases and was associated with lower CSF Aβ40 and Aβ42 levels. Conclusions This nationwide registry highlights the marked clinical, radiological and biomarker heterogeneity of CAA, including sex-specific patterns and frequent AD-like biomarker profiles, supporting the integration of biomarkers into future diagnostic frameworks. Conflict of interest None of the authors has anything to disclose. Table 1 - belongs to Results