Up to eighty percent of dementia cases are Alzheimer's and yet today's treatments have only short-term results that peter out after just a year. A new drug though is showing great promise. It sharply reduced cognitive decline for people with early dementia in a small clinical trial.

The new drug, aducanumab, targets beta-amyloid protein which builds up in the brains of Alzheimer's patients, damaging neurons. The drug triggers an immune response that helps to get rid of this protein.

One hundred sixty six people in early stages of dementia and with protein plaques in their brains enrolled in the study. They were randomly given the drug or a placebo. The researchers had expected to see a twenty to thirty percent reduction in cognitive decline, but much to their surprise, patients given high doses of the drug experienced a seventy percent reduction in mental impairment.

One major side effect was a localized swelling of the brain which occurred in half the patients genetically predisposed to Alzheimer's, but just seventeen percent in those without the genetic variant. Fortunately, the swelling did not cause symptoms, so it's possible that by changing the drug's dose the swelling can be controlled.

Also, with new imaging that can determine plaque accumulation, people with the potential to develop dementia can be identified earlier and receive treatment. Though the results are encouraging, other drugs that initially showed encouraging results did poorly in large clinical trials. Everyone's hoping this drug will be different. Alzheimer's may triple by 2050 unless we find a breakthrough to significantly delay its onset or develop a cure.