While the data for the tau drugs "aren't definitive at this point, " says the Mayo Clinic's Ronald Petersen, they do provide researchers enough of a signal to continue forward in larger trials that may provide more definitive results.
He argues that the amount of amyloid in patient brains doesn't correlate much with dementia, and blocking tau, a second protein that accumulates in the brain cells of demented patients, as his company is doing is a much better way to go.
He argues that the brain is armed with mechanisms for clearing the tau protein and that the reason it doesn't in people with Alzheimer's disease is because the protein is protecting the neurons.