Perhaps it arrests the typical Alzheimer’s decline, once initiated as a preventative treatment. The amyloid kills neurons and causes permanent structural changes to the brain. It seems to act to stop any further damage occurring, without actually regenerating brain tissue.
Stroke patients can regain function by the retraining of healthy portions of the brain to perform the functions of areas which became injured. Perhaps the losses to Alzheimer can be compensated for in an analogous fashion.
Yes , this was mentioned as a possible use for prevention in the original news source article.
The key question is whether the build up of amaloyoid proteins was the cause , or a symptom of the disease.
Further studies , and Class studies will be needed involving larger numbers of participants to demonstrate effectiveness.