The evidence to date makes it clear that Alzheimer’s disease isn’t a condition in which amyloid-β alone drives progression of neurodegeneration. There is significant synergy between the aggregation of amyloid-β and tau protein, and between portions of the surrounding biochemistry. It isn’t the solid deposits of amyloid-β and hyperphosphorylated tau that are the direct cause of cell dysfunction and death, but rather complex interactions related to these aggregates. Various studies have provided evidence to suggest that amyloid-β spurs tau aggregation, as well as vice versa, and it may be the case that both are true. The work here adds to the evidence for neurodegeneration to start with amyloid-β accumulation, which increases the pace at which tau aggregation later takes place. When it comes to actual damage to the brain, both cause significant harms, however.
Years ago, researchers noted that people with Alzheimer’s disease have high levels of tau in the cerebrospinal fluid, which surrounds their brain and spinal cord. Tau – in the tangled form or not – is normally kept inside cells, so the presence of the protein in extracellular fluid was surprising. As Alzheimer’s disease causes widespread death of