Progress in developing drugs that arrest the fatal brain disease has been frustratingly slow, in part because the studies largely involve patients whose brains are already wrecked by the disease, they said at the Alzheimer's Association meeting in Honolulu.

An international study known as the Dominantly Inherited Alzheimer Network, or DIAN, is set up to follow families with early onset familial Alzheimer disease, or eFAD, who make up 1 percent to 5 percent of the 26 million cases of Alzheimer's disease globally.

"The only people that we know of that are 100 percent destined to get Alzheimer's disease are these people with these mutations," Dr. Randall Bateman of Washington University in St. Louis and a DIAN investigator, said in an interview at the meeting.

People with the mutation typically develop Alzheimer's disease in their 50s, but symptoms can start as early as in their late 20s. They produce an excess of a protein linked with Alzheimer's known as beta amyloid, which is the main target of most drugs in late-stage testing.

Current Alzheimer's drugs, including Eisai Co and Pfizer Inc's Aricept, or donezepil, and Forest Laboratories' Namenda, or memantine, treat symptoms, but so far nothing has been shown to improve memory and thinking in people with the disease.

Bateman said that may be because they are testing too late in the disease, and he thinks the DIAN study, in which patients are sure to get the disease, may offer a way to test these drugs earlier, before symptoms appear.

"It's nearly impossible to treat someone with a new therapeutic agent that has potential toxicities if you don't know that person is going to get Alzheimer's disease," he said.

The DIAN researchers met this week with drugmakers at the Alzheimer's Association meeting to talk about how to structure clinical trials. So far, 12 major companies are have expressed an interest, Bateman said.

"We're having these discussions with everybody to see what drugs are going to be available, what will the properties be, how they can be implemented," he said.

Next, the companies will submit formal requests to a committee that will pick the best drugs for the study.

"Not all would be ideal. We have to exercise some selection on our end," said Dr. John Morris of Washington University, principal investigator for the DIAN study, which is funded by the National Institute on Aging.

There is no money in the study to pay for drug trials, so companies will have to contribute if they want to participate.

Bateman, who is running the treatment arm of the trial, said he thinks the study will be able to accommodate the most promising drugs already in late or midstage studies in people with the more common, late-onset form of Alzheimer's disease.

Dr. Eric Siemers of Eli Lilly and Co, which has four molecules in clinical development for Alzheimer's disease including two in late-stage clinical trials, said the DIAN study offers a great opportunity to test drugs.

"It's a way to do a proof of concept study. If you have a mutation, you know 100 percent that you will get the disease," said Siemers, who is medical director for Alzheimer's disease at the company.

Researchers say another compound likely to be tested is bapineuzumab, an antibody treatment being developed jointly by Pfizer Inc, Irish drugmaker Elan Corp and Johnson & Johnson.

No drugs have been picked, but it will happen soon. Bateman hopes to get clinical trials started as early as next year.

He likens the drug studies to early testing of popular cholesterol-lowering treatments known as statins, the world's biggest selling drugs, which were first tested in people genetically predisposed to develop high cholesterol.

"I think if (a drug ) is shown to work in this population it will certainly have some impact on Alzheimer's disease," Bateman said.

(Editing by Steve Orlofsky)