Alzheimer’s disease seems to spread like an infection from brain cell to brain cell, two new studies find. But instead of viruses or bacteria, what is being spread is a distorted protein known as tau.
The surprising finding answers a longstanding question and has immediate implications for developing treatments, researchers said. And they suspect that other degenerative brain diseases like Parkinson’s may spread in a similar way.
Alzheimer’s researchers have long known that dying, tau-filled cells first emerge in a small area of the brain where memories are made and stored. The disease then slowly moves outward to larger areas that involve remembering and reasoning.
But for more than a quarter-century, researchers have been unable to decide between two explanations. One is that the spread may mean that the disease is transmitted from neuron to neuron, perhaps along the paths that nerve cells use to communicate with one another. Or it could simply mean that some brain areas are more resilient than others and resist the disease longer.