Researchers think they are close to devising a deceptively simple way to prevent the progression of Alzheimer's disease a nasal spray vaccine.
The vaccine, which so far has only been tested on mice, is a combination of two medications Protollin and glatiramer acetate (Copaxone), which has already been approved to treat other conditions, including multiple sclerosis (MS).
The spray targets the abnormal buildup of beta-amyloid plaque in the brain. Although scientific evidence is not sufficient to prove that this amyloid accumulation is the main cause of Alzheimer's disease, many researchers believe that it is.
The researchers sought to design a vaccine -administered via drops in the nose-that would initiate an amyloid-cleansing process by triggering the immune system without provoking antibody development, a problem that occurred in previous trials.
Study coauthor Dr. Howard L. Weiner, codirector of the Center for Neurologic Diseases at Brigham and Women's Hospital, and his colleagues targeted microglial cells, which essentially eat away the amyloid build-up. The researchers tried to produce a vaccine that would stimulate these microglial cells into action.
Mice that had a similar amount of beta-amyloid plaque in their brains as what would be present in a human Alzheimer's patient, were given an initial four doses of the vaccine in the first week, followed by weekly doses for the next six weeks. The research team began monitoring the mice one week after vaccination began. They were looking for signs of disease, paralysis, limb weakness and fatigue.
Ultimately, brain tissue was dissected and examined for evidence of both amyloid quantity and any toxic side effects that might have developed in reaction to the vaccine.
The authors found that, overall, amyloid plaque levels in the vaccinated mice were reduced by 73%. None of the vaccinated mice showed any evidence of toxic side effects.
"I'm very hopeful [that this vaccine] could stimulate the immune system to reduce this buildup among people with early signs of Alzheimer's as well as for those in later stages of the disease," says Weiner.
The Next Step
Weiner and his team say they hope to begin small-scale testing of the Alzheimer's nasal spray vaccine in people following talks with the US Food and Drug Administration (FDA). They note that the human trial process will take time, so a nasal Alzheimer's vaccine is, at best, several years away from clinical use.
Weiner notes that although there are a number of different research projects currently exploring the possibility of reducing beta-amyloid buildup in the brain, none has yet been shown to work in people. And he emphasizes that transitioning from animals to people is a tricky process that doesn't always work.
"But I'm very enthusiastic," he says. "I think it has a good chance of working and helping Alzheimer's patients-and even opening up a new avenue for developing a vaccine for MS."