Blood Product May Treat Alzheimers Disease
Sept. 15, 2004 -- An existing treatment for immune disorders may help people with Alzheimer's disease, a very small clinical study suggests.
The treatment is intravenous immunoglobulin. Also known as IVIG, gamma globulin, immune globulin, and immune serum, the product comes from plasma, the liquid part of blood. IVIG is a collection of the germ-fighting molecules called antibodies that course through healthy people's blood.
The idea that normal people have antibodies that might help Alzheimer's patients comes from Richard Dodel, MD, associate professor of neurology at Friedrich Wilhelms University in Bonn, Germany, and Yansheng Du, PhD, assistant professor of neurology at Indiana University in Indianapolis.
In Alzheimer's disease, a sticky plaque clogs the brain. The main ingredient of this plaque is a deviant molecule called beta amyloid. Why, Dodel and colleagues wondered, don't normal people have problems with beta amyloid? Maybe, they thought, it's because they have anti-amyloid antibodies.
"So we looked for them and found anti-amyloid antibodies in normal blood," Dodel tells KB120. "Every one of us has them. And they are not just antibodies against something else that happen to stick to amyloid. They are really highly specific for beta amyloid."
IVIG vs. Amyloid in Patients With Alzheimer's Disease
What happens to amyloid when a person gets an infusion of IVIG? Dodel and colleagues looked at the blood and spinal fluid of 10 patients with various neurological conditions -- not Alzheimer's disease -- who received IVIG. They found that amyloid levels went down in the brain but up in the blood.
This, Dodel suggests, might mean that the antibodies carry the amyloid out of the brain for eventual elimination by the body. Or it might mean that the antibodies catch the amyloid and mark it for destruction within the brain.
But would it work in Alzheimer's disease? Dodel's team gave commercial IVIG to five Alzheimer's disease patients for six months.
Sure enough, their brain levels of beta amyloid went down by 30%, while their blood levels of beta amyloid more than doubled.
Patients' mental function improved very slightly over the six months of treatment. But it didn't get worse. That's a promising sign, but it doesn't prove anything, Dodel is quick to say.
"The goal of this pilot study is to create interest in a large clinical trial -- with 60 to 80 patients -- and really answer the question, 'Does IVIG have an effect on cognition?'" Dodel says.
That sounds like a good idea, says JoAnne McLaurin, PhD, of the Center for Research in Neurodegenerative Diseases at the University of Toronto, Ontario. McLaurin notes that a recent effort to raise anti-amyloid antibodies with an Alzheimer's vaccine showed promise but had to be stopped when some patients developed life-threatening encephalitis, an inflammation of the brain.
It will be a while before another such test of active immunization can take place. But passive immunization -- giving a person premade antibodies such as IVIG -- might work, McLaurin suggests.
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