"We are encouraged by the pooled data that appear to show a slowing of cognitive decline," said John Lechleiter, Lilly's chief executive officer, in the statement.

Solanezumab is an antibody that targets beta amyloid fragments found in the brains of people with Alzheimer's disease. These abnormal clumps of protein are suspected of damaging and eventually killing brain cells. It is the first drug in its class to show positive results in people with mild Alzheimer's.

• STORY: Pfizer pulled plug on Alzheimer's drug trial

Eli Lilly reported the trial didn't meet some of the goals of changing patient behavior or functioning, but researchers have been saying they would not be surprised by that outcome eventually. However, the positive results Eli Lilly reported were among the targets Lilly identified ahead of time. The changes caused by the treatment could also include lower levels of amyloid detected in blood and brain imaging, and could mean the disease would not progress to more debilitating stages.

An independent analysis of the data is being performed by the Alzheimer's Disease Cooperative Study (ADCS), an academic national research consortium. ADCS will present findings at the American Neurological Association (ANA) meeting in Boston on Oct. 8.

Eli Lilly's trial of solanezumab included more than than 2,050 patients with mild-to-moderate Alzheimer's disease in 16 countries, studied over 18 months. The overall group showed slower decline, as did the subgroup of patients with the more mild symptoms.

"We would have love to have these trials meet their goals, but there is new, hopeful and encouraging information here,'' says Bill Thies, chief medical and scientific officer for the Alzheimer's Association. "This is a first. I think it's also encouraging that people in the trial will continue to receive the treatment so we'll have more data down the road."

No treatment exists to slow the progression of Alzheimer's disease. Meanwhile, 5.4 million people have the disease in the USA, numbers expected to triple as Baby Boomers age. Pfizer discontinued a trial several weeks ago when the treatment (bapineuzumab) failed to change cognitive and functional performances. However, an analysis of its data is still being made to see whether it slowed the progression.

Recent research suggests the Pfizer and Eli Lilly trials might not have started soon enough in the disease process. Biological markers of the disease begin to appear as early as 20-25 years before symptoms start.

Following the failure of the Pfizer trial, also done in people with mild to moderate Alzheimer's, researchers were disappointed but not surprised.

"There is a movement to treat people earlier for Alzheimer's," Thies says.

The next steps for solanezumab have not yet been decided and will be determined after discussions with regulators, Eli Lilly reported.

"If this finding can be duplicated, it suggests that an Alzheimer's therapy targeting beta amyloid can have a beneficial effect on cognitive abilities in people with mild to moderate Alzheimer's," says Thies, adding that would be a major step forward in the fight against Alzheimer's.