Seattle ? If treatment to prevent Alzheimer’s disease is going to work, it may have to begin in middle age – or even younger, new research by Seattle scientists suggests.

The researchers found that in people genetically prone to Alzheimer’s, significant amounts of a brain-clogging protein start moving from the spinal fluid to the brain at age 50 or younger.

Previous research has indicated that Alzheimer’s begins years before symptoms appear. But this work is the first to look at early signs across a wide range of ages – from 21 to 88.

The research is particularly significant because scientists predict a dramatic increase in Alzheimer’s in the decades ahead. About 4.5 million people in the United States have the disease, and researchers say that could increase to 16 million by 2050.