The underexplored question of β-amyloid monomers
Conceived more than 25 years ago, the amyloid cascade hypothesis of Alzheimer's disease has evolved to accommodate new findings, namely different forms of β–amyloid aggregates and downstream dysfunctions. Yet, the cascade does not mention its very beginning, the β–amyloid monomer. Here, I will discuss the monomer from a functional evolutionary perspective, highlighting the potential advantages of a native unfolded state that, however, involves an amyloidogenic risk. Finally, I will make a summary of what is known about its functional role in the brain and discuss the implications of its conceivable shortage in the development of Alzheimer's disease.