Cerebrovascular Lesions in Alzheimer-associated Diseases – A Neuropathological Study with 7.0-tesla Magnetic Resonance Imaging

Mixed dementias are clinically under-recognised and need neuropathological confirmation. The most frequent types are those composed of Alzheimer’s dementia (AD) associated with cerebral amyloid angiopathy (CAA), cerebral arteriosclerotic micro-angiopathy (CAMA) and Lewy body disease (LBD). The present neuropathological study with 7.0-tesla magnetic resonance imaging (MRI) compares the impact and the distribution of cerebrovascular lesions between unmixed AD brains to those with different types of associated disorders. Twenty-six unmixed AD brains were compared to 12 associated with LBD, eight with CAMA and 24 with CAA. On neuropathological examination brains with AD-CAA had the most severe cerebrovascular lesions, those with AD-CAMA had a higher number of lacunes and in the AD-LBD brains only an increase of cortical micro-infarcts was observed. On MRI examination, white matter changes were only increased in the AD-CAA group. Cortical micro-infarcts were significantly more frequent in all the sections of the AD-CAA and AD-CAMA groups. In the AD-LBD brains, they were only moderately more common in the occipital section. Cortical micro-bleeds were observed in all mixed dementia cases. A moderate amount of superficial siderosis was only seen in the AD-CAA brains. The present study confirms our previous findings that CAA and CAMA are the main causes of occurrence of different cerebrovascular lesions in the mixed AD brains.