Researchers have discovered a gene that appears to affect the immune system's ability to protect against alzheimer's disease.
alzheimer's experts have long focused on plaque build-up in the brain -- a hallmark of the disease.
but now -- two separate groups of researchers stumbled upon a mutated gene that brings the immune system into the mix.
the gene appears to interfere with the immune system's ability to prevent plaque from accumulating in the brain.
experts say the mutation increases the risk for alzheimer's disease by three to five times.