Results from a large clinical trial revealed that Alzheimer’s drug bapineuzumab failed to affect cognition or everyday functioning in Alzheimer’s patients with a genetic mutation.

“There was absolutely no evidence at all of a clinical benefit of treatment on either of the primary measures, one cognitive and one functional,” said Dr. Reisa Sperling, a researcher and director of the Center for Alzheimer Research and Treatment at Brigham and Woman’s Hospital in Boston.

The New York Times reported that several scientists and investors anticipated the drug’s failure in the clinical trial, which studied 1,100 patients with mild to moderate cases of Alzheimer’s disease and a genetic mutation of the gene ApoE4. According to the National Institutes of Health, 25 to 30 percent of Alzheimer's patients have the gene, and the percentage increases to 40 in late-onset cases.

Bapineuzumab, a monoclonal antibody, works to destroy or stop the production of harmful protein beta-amyloid, which sticks together to create plaques in the brain. While no one knows the exact cause of the disease, some scientists believe this process may contribute to the cell death that causes Alzheimer’s symptoms, according to MedicineNet.

The New York Times reported, however, that the many failed clinical trials of drugs that target beta-amyloid have left experts skeptical.

Dr. Samuel Gandy, director of the Center for Cognitive Health at the Mount Sinai School of Medicine in Manhattan, believes that plaque can start to form up to 25 years before Alzheimer’s symptoms surface and that, “All these symptomatic trails are 25 years too late.”

According to MedicineNet, Alzheimer’s disease develops over time and impairs cognition, interfering with functions such as the ability to reason, plan, use language and perceive. The disease manifests in old age and may affect about 50 percent of individuals over the age of 85.

While drugs exist that can treat the symptoms of Alzheimer's, they can only slow the progression of the disease. The New York Times said researchers have begun to employ imaging and other tests to find plaque before Alzheimer’s symptoms appear, hoping to prevent the disease altogether.

CBS News reported that two studies on patients who do not have the ApoE4 gene will continue. Pfizer and Johnson & Johnson expect results in weeks.