Possible marker for dementia disease.

Possible marker for dementia disease

Researchers have found abnormal proteins in the cerebrospinal fluid of people with Creutzfeldt-Jakob disease (CJD), a rare, fatal brain disorder. The proteins, they say, could prove useful as a marker, as well as a handle on what causes they mysterious disease.

Whatever causes CJD is known to be transmissible, and can take three years or more to cause problems. The disease can sometimes look like other progressive dementias such as Alzheimer's disease, but its course is quite different: Once symptoms appear, death usually occurs within a year. At the moment, definitive diagnosis can be made only by studying brain tissue.

Michael G. Harrington, D. Carleton Gajdusek and their colleagues at the National Institutes of Health in Bethesda, Md., cast a wide net in their search, studying proteins in the cerebrospinal fluid of 100 healthy people, 21 CJD patients and more than 400 patients with other neurological diseases. They used a procedure called two-dimensional electrophoresis, separating cerebrospinal fluid proteins based on relative acidity and on size.

In the July 31 NEW ENGLAND JOURNAL OF MEDICINE, they report finding two proteins present in all 21 CJD patients and in 5 of 10 patients with a herpes brain infection, but not in fluid from the other people. The herpes infection

is easily distinguishable from CJD.

"It suggests very strongly there will be a diagnostic potential," Harrington told SCIENCE NEWS. The finding will first have to be replicated by other laboratories and the test will have to be made simpler, he says.

The proteins may also provide a clue about how the disease originates. Determining the makeup of the two proteins will allow the researchers to search for the genes that code for the proteins. If the genes aren't in normal cells, it could mean they're in a virus or some other infectious agent. "We don't know [the proteins' role] in the disease," says Harrington. "But something is producing them fairly selectively."

Stanley B. Prusiner of the University of California at San Francisco, who has identified a unique self-replicating protein, called a prion, that he believes causes CJD, says that while the research is interesting, it contains two troublesome points. The researchers did not find the proteins in the spinal fluid of three patients with kuru, a disease Prusiner's lab has found to be identical to CJD. And finding the proteins in people with the herpes brain infection makes it unlikely they are specific to CJD, Prusiner says.