The Alzheimer’s drug crenezumab did not slow or prevent cognitive decline in a long-running study of Colombian families who carried a genetic mutation that put them at near certain risk to develop the mind-robbing disease. 

The study of 252 people tested whether the pharmaceutical giant Roche’s antibody crenezumab could slow or halt the disease if participants took the medication before memory or thinking problems surfaced. But the drug did not demonstrate a significant benefit in tests measuring cognitive abilities or memory function among study participants, Roche said Thursday in a news release.

The widely anticipated study that began enrolling patients in 2013 sought to test the idea that Alzheimer’s disease could be prevented or delayed if otherwise healthy people took a medication years before developing memory and thinking problems. To that end, Roche teamed with researchers from Phoenix-based Banner Alzheimer’s Institute and the University of Antioquia in Colombia, who first identified the extended families with a rare genetic mutation that brought on Alzheimer’s disease early, usually when they were in their mid-40s.

Study participants who inherited the genetic trigger, known as the paisa mutation, were randomly assigned to either get the drug or a placebo. Another placebo group included people without the mutation. None of the participants knew their genetic status when receiving the drug or placebo.

Crenezumab is part of a class of antibody drugs designed to counter amyloid beta protein accumulation in the brains of Alzheimer’s patients. Amyloid is one of the known markers of Alzheimer’s, and researchers theorize that if the drug could clear amyloid from people before they developed symptoms, it could delay or halt the disease. 

Roche and Banner Alzheimer’s Institute said small differences favoring the drug over the placebo were observed but did not rise to the level of being statistically significant. Roche will release initial data from the trial Aug. 2 at the Alzheimer’s Association International Conference in San Diego.

 “We’re disappointed that the treatment did not demonstrate a statistically significant clinical benefit,” said Eric Reiman, Banner Alzheimer’s Institute’s executive director and a study leader. “At the same time, we’re proud of the impact that this precedent-setting trial has had in shaping a new era in Alzheimer’s prevention research, and we’re extremely grateful to our research participants and their families.”