Alzheimer's Disease Health Center

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Brain Shunts Slow Alzheimer's Disease

Devices Clear Proteins From the Brain That May Cause Disease

WebMD Health News

Oct. 22, 2002 -- Draining toxin-filled fluid from the brain with special shunts may help slow the progression of Alzheimer's disease, according to a study examining the procedure.

The study, published in the Oct. 22 issue of Neurology, found that Alzheimer's symptoms stabilized in patients fitted with the shunts, whereas those not receiving the devices had a steady decline in memory and other intellectual functions.

"I'm very encouraged by our findings," says neurologist and lead researcher Gerald Silverberg, MD, of Stanford University School of Medicine. "The differences between the two groups was not expected."

But others are quick to note that it's too early to tell if this shunting procedure will be effective, since Silverberg's study -- the first of its kind -- only included 23 patients by FDA mandate, and researchers knew which patients were implanted with shunts. There was no difference in their age or the severity of their disease.

Psychological testing showed a trend in favor of the patients who received the shunts, but the finding wasn't particularly significant, notes David Drachman, MD, chairman of the department of neurology at the University of Massachusetts School of Medicine and a spokesman for the American Academy of Neurology.

Since everyone was aware of which treatment each patient was getting, there is no way to know how many people who didn't get the shunts might have done as well as those who did, he tells WebMD. "In all, the possibility that shunting of spinal fluid might benefit some patients with Alzheimer's disease is worth investigating further."

Shunting is believed to help slow the progression of Alzheimer's by allowing protein-filled cerebrospinal fluid (CSF) to be drained from the head to the stomach at a regulated rate. This allows the body to create fresh, toxin-free CSF to fill the empty spaces around the brain and spinal cord.

"The leading theory is that Alzheimer's is caused by a clearance problem in the brain, and the most likely culprit is amyloid beta proteins," says Silverberg. "Steady concentration of these proteins increases in people who will develop Alzheimer's."

When not "cleared," amyloid stagnates and can form plaques that damage brain cells, causing memory loss and other symptoms associated with the disease, which affects about 4 million Americans and one in 10 people older than age 85.

In the procedure, the shunts are implanted about 3 inches into the head behind the ear, and a thin tube implanted beneath the skin drains a small amount of CSF to another shunt in the stomach. Patients wear the devices for life.

The study participants were evaluated for intellectual function at the start of the one-year study, then every three months. The CSF was also evaluated for protein content.

"We saw a 60% decline in tau protein in those patients fitted with the shunts," says Silverberg. "These proteins never decrease in untreated Alzheimer's patients." Tau proteins, which also accumulate in CSF, are suspected to contribute to the disease.

However, some patients receiving the shunts experienced complications, including seizures, shunt infection, and severe headache. The device also malfunctioned in two patients.

Silverberg tells WebMD that he is conducting a larger study on 256 patients at 25 institutions across the U.S. that further evaluates shunting. In that study, which will take two years, half the patients will receive working shunts and the other half will get non-working devices. Neither researchers nor patients will know who is fitted with working shunts until results are completed.

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