Treating Alzheimer's disease by removing cerebrospinal fluid from the brain has been shown effective by researchers from Stanford University, University of Washington (Seattle) and the Barrow Neurological Institute in Phoenix.

Researchers tested the theory that improving cerebrospinal fluid turnover by use of a shunt will slow or stop the progression of dementia in people with Alzheimer's disease. A shunt is a tube inserted into the brain's lateral ventricle, then hooked into a small reservoir that controls the flow of cerebrospinal fluid to gradually drain the fluid away to the abdominal cavity where it is reabsorbed by the body.

Cerebrospinal fluid shunting for dementia was first studied in 1969 but did not become a valid method of treatment because of mixed clinical results and an unacceptably high incidence of adverse events related to the shunts. Recently studies using cerebrospinal fluid shunts to treat patients with hydrocephalus (water on the brain) showed a coincidental lack of cognitive decline in patients who also suffered from Alzheimer's disease.

"We speculated that, although the subjects described in these recent studies may have had two unrelated diseases, both Alzheimer's and normal pressure hydrocephalus may be part of a disease spectrum whose primary determinant is cerebrospinal fluid circulatory failure," said Dr. Gerald Silverberg of Stanford University and author of the study.

Researchers conducted a clinical trial in which an investigational low-flow shunt was evaluated in Alzheimer's patients. The surgically implanted shunts drained cerebrospinal fluid at a constant rate much lower than in the hydrocephalus studies to minimize the potential for overdrainage and optimize constant cerebrospinal fluid flow.

The 24 study patients were screened and placed into either a test or a control group. Both the control and study patients were tested at the start of the study and every three months afterward using a reading test, dementia rating scale and mental status examination.

There were no substantial differences in age or severity of dementia between the shunted patients and the control group at the start of the study. However, the shunted patients experienced relatively stability while the control patients demonstrated a fairly robust decline in cognitive function over the next year.

"Our preliminary safety and efficacy data, including the outstanding questions they present, suggest that more definitive testing is appropriate," concluded Silverberg. A larger, multi-center clinical trial is underway.

Other sources: American Academy of Neurology