Cerebral Microbleeds and Superficial Siderosis: Vascular Correlates and Cognition in a Memory Clinic.

OBJECTIVE: Cerebral microbleeds (CMBs) and cortical superficial siderosis (cSS) are increasingly recognized in patients with cognitive impairment and are considered markers of cerebral small vessel disease and cerebral amyloid angiopathy (CAA). However, their associated variable and cognitive impact remain under-characterized in memory clinic populations. METHODS: We retrospectively reviewed 2923 patients referred for cognitive complaints who underwent brain MRI at the University Health Network (Toronto, 2014-2022). Of these, 137 patients with CMBs and/or cSS were compared with 278 control patients without hemorrhagic findings, sampled at an approximately 2:1 ratio from the CMB/cSS-negative pool. We analyzed vascular-associated variable, Fazekas-rated white matter hyperintensities (WMH), lesion location and cognitive performance (Mini-Mental State Examination or Montreal Cognitive Assessment). Probable CAA was classified using Boston Criteria v2.0. RESULTS: CMBs and/or cSS were present in 4.7% of the cohort. Of the 137 cases, 103 had CMBs only, 9 had cSS only and 25 had both. Thirty-one patients (22.6%) met criteria for probable CAA. The CMB/cSS group was older, had higher rates of hypertension and had greater WMH burden. Cognitive scores were lower in the CMB/cSS group, but in multivariable models, only lower education remained a significant predictor. WMH severity showed a stronger association with cognitive performance than the presence or topography of CMBs or cSS. CONCLUSION: CMBs and cSS co-occur with vascular-associated variables and WMH burden, while their independent association with cognition is modest in cross-sectional analyses. The proportion meeting probable CAA supports diagnostic relevance. Considering hemorrhagic markers alongside WMH may better characterize vascular contributions to dementia in routine clinical assessment.