The toxic Aβ oligomer and Alzheimer's disease: an emperor in need of clothes

The 'toxic A beta oligomer' hypothesis has attracted considerable attention among Alzheimer's disease researchers as a way of resolving the lack of correlation between deposited amyloid-beta (A beta) in amyloid plaques-in terms of both amount and location- and cognitive impairment or neurodegeneration. However, the lack of a common, agreed-upon experimental description of the toxic A beta oligomer makes interpretation and direct comparison of data between different research groups impossible. Here we critically review the evidence supporting toxic A beta oligomers as drivers of neurodegeneration and make some suggestions that might facilitate progress in this complex field.