Overlap between pathology of Alzheimer disease and vascular dementia

There is overwhelming evidence to suggest that the neuropathology of Alzheimer disease (AD) extends beyond amyloid plaques and neurofibrillary tangles. Review of various consortium data shows that more than 30% of AD cases exhibit cerebrovascular pathology. However, certain vascular lesions such as cerebral amyloid angiopathy, microvascular degeneration, and periventricular white matter lesions are evident in almost all cases of AD. Whether these vascular lesions are coincidental or causal in the pathogenetic processes of AD remains to be defined. Although systemic vascular influences such as hypertension, coronary artery disease, and other cardiovascular disturbances may be responsible for such pathology in AD, it is equally intriguing that about one third of patients diagnosed with vascular dementia (VaD) will have AD-type pathology at autopsy. Moreover, previous studies have revealed that deficits in cholinergic indices related to the basal forebrain neurones are apparent in multi-infarct dementia. In this short review, we evaluate cerebrovascular pathology of AD in light of peripheral vascular pathophysiology implicated in the etiopathogenesis of the dementia. We also consider pathological findings in relation to genetic influences such as apolipoprotein E that may shed light on the link between AD and VaD. In view of these commonalties, it is reasonable to consider the same treatment strategies for both AD and VaD.