Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Study Will Test Drug for Alzheimer's Prevention

An experimental drug called solanezumab will be used in a large U.S. government-funded study that will assess if it's possible to prevent Alzheimer's disease in seniors at high risk for the brain disorder.

Previous research found that the drug -- which is meant to help clear the amyloid plaques that are a main cause of Alzheimer's -- did not help patients with moderate to severe disease, the Associated Pressreported.

However, solanezumab did show some promise in people with milder Alzheimer's and researchers believe it might help this group of patients.

"The hope is we can catch people before they decline," Dr. Reisa Sperling, who is director of the Alzheimer's center at Brigham and Women's Hospital in Boston and will help lead the new study, told the AP.

The clinical trial will include 1,000 people ages 70 to 85 whose brain scans reveal plaques but who do not yet show any signs of dementia. The patients will receive monthly infusions of either solanezumab or a placebo for three years.

The main objective of the study will be to slow the rate of the patients' mental decline. Sperling said the research will be conducted at 50 locations in the U.S. and possibly others in Australia, Europe and Canada, the APreported.

Solanezumab is an Eli Lilly & Co. drug.

About five million people in the U.S. have Alzheimer's, which is the most common type of dementia. Current medicines can easy symptoms, but there is no known cure.

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Global Treaty Seeks to Reduce Mercury Emissions

More than 140 nations on Saturday adopted a legally binding international treaty to reduce emissions of mercury, which poses a number of health risks.

The deal seeks to reduce mercury pollution from utility plants, mining, industrial processes, and a wide range of consumer products. This would be done by setting enforceable limits and by promoting alternatives in which mercury is not used, released or emitted, the Associated Pressreported.

Mercury can cause nerve damage, brain and kidney damage, memory loss and language impairment.

The treaty "will help us to protect human health and the environment all over the world," Swiss environment ambassador Franz Perrez told a news conference, the APreported.