[Vascular cognitive impairment: the relationship between hypertensive small vessel disease and cerebral amyloid angiopathy].

Vascular cognitive impairment comprises a spectrum ranging from the prodromal stage of vascular mild cognitive impairment (v-MCI) to full-brown vascular dementia with a varying degree of Alzheimer's pathology and vascular comorbidity. In this review, we discuss the relationships of hypertensive small vessel disease (HSVD) and cerebral amyloid angiopathy (CAA), which are the representative types of subcortical and cortical small vessel diseases, respectively. HSVD predominantly affects the penetrating artery territories, and CAA is located at the cerebral cortices admixed with senile plaques and neurofibrillary tangles. The former causes lacunar infarcts and white matter lesions, whereas the latter results in subcortical hemorrhage and white matter lesions. Recent development in magnetic resonance imaging has enabled differentiation of CAA-related micro-lesions including lobar cerebral microbleeds, cortical subarachnoid hemorrhage, and cortical microinfarcts. Both HSVD and CAA are differentially located in the brain, but patients with higher degree of CAA are predisposed to have more severe HSVD. Therefore, it is likely that these diseases progress in concert with each other with advancing age. The interaction between HSVD and CAA may explain the pathophysiology of VCI and but further investigations are required to understand this.