Glimmer of hope from new Alzheimer's drug

An experimental medication may slow the progression of mild Alzheimer's disease if people take it early enough, according to research presented today at the Alzheimer's Association International Conference in Washington, D.C.

The drug, solanezumab from the pharmaceutical company Eli Lilly & Co., is one of only a handful of medications in late-stage testing in the search for a treatment to combat the devastating disease that affects over 5 million Americans.

The medication is designed to target and remove the sticky protein called amyloid that accumulates in the brain of Alzheimer's patients. Over the course of two years, the researchers observed a slight decline in the progression of the disease in the patients who'd been taking the drug.

"It's really the first drug to hit the underlying cause of the disease rather than symptoms of the disease, so there's excitement and there's hope - two words you never hear with Alzheimer's," CBS News contributor Dr. David Agus told "CBS This Morning."

"It's not dramatic, but in the course of the study over two years, there was a slight decline in how the patients lost memory function," he said. The drug is given via IV infusion once a month.

The findings, however, do not offer decisive proof that solanezumab works and many researchers are looking at the results with cautious optimism.

"These are not definitive reports that are going to lead to medications being approved tomorrow. What they represent is an important foundation for us moving forward," Dr. David Knopman of the Mayo Clinic, who has monitored some of Lilly's data, told the Associated Press.

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The drug was previously tested in a larger group of Alzheimer's patients with mild to moderate levels of the disease. Though it failed to help patients overall, the researchers reported in 2012 that it might be helping those with very mild symptoms, appearing to slow their mental decline by about a third.

They continued to track its effect in that group of patients for another two years, giving the drug to both patients who had initially received it and those who were initially given a placebo.

The group that had taken the drug from the beginning fared better -- suggesting the treatment may actually slow the progression of the disease if started sooner -- but the difference was small.

Clinical trials involving solanezumab are ongoing and more results are expected in late 2016.