Vascular aspects in Alzheimer's disease

Alzheimer's disease is a primary degenerative dementia and is not considere d to be of vascular origin. Furthermore, severe cerebrovascular diseases ar e generally exclusionary for the clinical diagnosis. During recent years bo th epidemiological and neuropathological studies have suggested an associat ion between Alzheimer's disease and several vascular risk factors, such as hypertension, inheritance of the apolipoprotein E epsilon 4 allele, coronar y heart disease, diabetes mellitus, ischaemic white matter lesions and gene ralised atherosclerosis. These findings may reflect an overdiagnosis of Alz heimer's disease in individuals with silent cerebrovascular disease or that cerebrovascular disease may affects the clinical expression of Alzheimer's disease. Further possibilities include that Alzheimer's disease may increa se the risk of vascular disease or that vascular disease may stimulate the Alzheimer's disease process. Similar mechanisms may also be involved in the pathogenesis of both disorders, such as disturbances in the renin-angioten sin system, apoptosis, and psychological stress.