Abstract
BACKGROUND: Multi-infarct dementia (MID), a severe form of vascular cognitive impairment, results from cumulative impact of multiple cerebral microinfarcts (MMIs). Current preclinical models primarily rely on unilateral induction of MMIs, which fails to reproduce bilateral lesion distribution and persistent cognitive decline characteristic of human disease. OBJECTIVE: To develop and characterize a modified bilateral MMI model that more accurately reflects the clinical and pathological features of MID. METHODS: Twelve-month-old male C57BL/6J mice underwent either unilateral or bilateral MMI induction by microsphere embolization via the internal carotid artery. Bilateral induction was achieved by transiently occluding the contralateral common carotid artery during microsphere infusion. Behavioral assessments using novel object recognition (NOR) and elevated plus maze (EPM) were conducted on days 7, 14, and 28 post-surgery. Histological Hematoxylin and Eosin staining and immunohistochemical analyses using antibodies against Iba1 and GFAP were performed to evaluate lesion distribution and neuroinflammation. RESULTS: The modified bilateral procedure successfully induced widespread infarcts across both hemispheres. Bilateral MMI mice exhibited significantly greater and persistent cognitive impairment, demonstrated by a reduced NOR discrimination index and decreased open-arm exploration in the EPM persisting through day 28, than did unilateral MMI mice. Histological analysis confirmed bilateral microinfarcts and significant increase in Iba1- and GFAP-positive staining, indicating robust and sustained bilateral neuroinflammation. CONCLUSION: This modified bilateral MMI procedure reproduces key pathological and functional features of human MID, overcoming the limitations of traditional unilateral models. The new model provides a clinically relevant platform for investigating mechanisms underlying vascular cognitive impairment and evaluating potential disease-modifying therapies.