If all goes according to plan, 1,000 older people who have no symptoms of Alzheimer’s disease, but who have an abnormal protein in their brains believed to be a hallmark of the illness, will be selected to test whether drugs can hold off the disease in a first of its kind study to be led by Boston scientists.
The proposed study, detailed Tuesday at the Alzheimer’s Association International Conference in Vancouver, received a preliminary thumbs up earlier this month from the National Institutes of Health, but the project’s leaders are awaiting a final decision on funding the project, expected in September.
“In this tough time of federal funding, we are keeping our fingers very tightly crossed,’’ lead researcher Dr. Reisa Sperling, an Alzheimer’s specialist at Brigham and Women’s Hospital, said in a phone interview.
Recent drug trials aimed at clearing the abnormal amyloid proteins in the brains of Alzheimer’s patients have produced disappointing results, with no apparent easing of symptoms, and researchers think that’s because the drugs were used too late.
Scientists believe that more than 50 percent of certain critical brain cells are already lost by the time a patient displays even mild cognitive impairment. There is no known cure for Alzheimer’s disease.
Sperling’s study would enroll 1,000 adults over age 70 who have amyloid plaques revealed by brain scans and who are exhibiting very subtle cognitive problems that are typically reported in people years before they are diagnosed with Alzheimer’s.
“They can come in and say, ‘my memory is not as good as it used to be’ because we have some data that suggests complaining about your memory is more likely to be seen in people who have amyloid in their brain, but are still normal,’’ Sperling said.
The three-year study will give half of the participants a drug designed to clear amyloid plaques, and the others a placebo, and researchers will track the rate of cognitive decline in both groups.
The scientists have still not chosen which drug they will use — they are awaiting results later this year of two other clinical trials on anyloid-clearing medications. But Sperling said that if their hypothesis is right, the group that receives the amyloid-clearing medications will have a 25 to 35 percent slower rate of decline, compared with those who are receiving a placebo.
Laurie Ryan, director of the Alzheimer’s Disease Clinical Trials division at the National Institute on Aging, said scientists now believe that the key to beating Alzheimer’s is to treat the disease before symptoms appear — much the same way patients with high cholesterol are given statin drugs to head off cardiovascular problems.
“People with Alzheimer’s do have amyloid in their brains, but it’s not clear that everyone who has amyloid in the brain will go on to develop Alzheimer’s,’’ Ryan said. “It’s one of the pieces to the puzzle.’’
Because of that uncertainty, participants in the study will receive counseling to help them understand that just because amyloid was detected in their brains that does not necessarily mean they will develop Alzheimer’s, Sperling said.
“The last thing we would want is for someone to hear they are amyloid-positive and try to harm themselves,’’ she said.
Sperling hopes to receive about $36 million in funding from the National Institute on Aging. The rest of the money for the $150 million project would come from pharmaceutical companies and private foundations, Sperling said.
“My hope is that by this time next year, we are ready to start enrollment,’’ she said.