The cause of Alzheimer's disease (AD) is unknown. This gap in knowledge has created a stumbling block in the search for a genuinely effective treatment or cure for this dementia. This article summarises the arguments for a causal role for either amyloid deposition or cerebrovascular pathology as the primary trigger in the development of non-genetic AD. A bare-bones survey of the published research reveals no compelling evidence that amyloid deposition is neurotoxic in human beings or that it results in neurodegenerative changes involving synaptic, metabolic, or neuronal loss in human or transgenic-mouse brains. By contrast, the data supporting AD as a primary vascular disorder are more convincing. Findings suggesting a vascular cause of AD come from epidemiological, neuroimaging, pathological, pharmacotherapeutic, and clinical studies. The consensus of these studies indicates that chronic brain hypoperfusion is linked to AD risk factors, AD preclinical detection and pharmacotherapeutic action of AD symptoms.