Story highlights An experimental drug cleared plaque from the brains of early stage Alzheimer's patients

But cognitive benefits of the Biogen drug have not been proved

(CNN) An experimental drug shattered and removed toxic plaques in the brains of patients with early-stage Alzheimer's disease, researchers said Thursday.

Given to patients once a month for a year, infusions of the drug aducanumab cleared the brain of the deposits, which experts believe play a crucial role in disrupting cellular processes and blocking communication among nerve cells.

Although most aging brains contain some plaques, the brains of Alzheimer's patients tend to have much more. The disease, the most common form of dementia, has no cure, although some treatments are available to alleviate symptoms. Treatments to slow the progression or reverse it have not panned out.

Cambridge, Massachusetts-based Biogen developed the drug aducanumab and funded the study, which primarily tested its safety in humans and was not designed to test for cerebral benefits for patients. Still, the condition of some patients who received the drug showed less decline than patients receiving a placebo.

The study, funded by the makers of aducanumab, split 165 participants into groups and treated them with monthly intravenous infusions of either aducanumab or a placebo over 54 weeks. Four groups of patients received the drug in four separate doses.

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