Is Simpler Always Better? The Case for Going Beyond the Amyloid Hypothesis in Alzheimer's Disease

Alzheimer's disease (AD) research has been dominated by the single-factor amyloid hypothesis in the last decades. Several other hypotheses have been proposed and increasingly attract attention considering the limited success of amyloid-based therapeutic strategies. Surprisingly, most published alternative etiological hypotheses for AD are similarly single-factor hypotheses, such as vascular, metabolic, mitochondrial, infectious, and inflammatory hypotheses, but the existence of so many different hypotheses suggests that AD is most likely a complex, multifactorial disorder. This inventory of different etiological hypotheses will hopefully help the field to move forward with explanatory models that consider the multifaceted aspects of this devastating disorder.