An experimental drug for Alzheimer’s disease (AD) was shown to both slow cognitive decline and clear the sticky protein clumps in the brain that are a hallmark of the devastating illness – for some patients.

Researchers presented the latest findings Wednesday at the  Alzheimer’s Association International Conference in Chicago, and while this drug is the first to affect both cognition and the neural tangles, the reception was mixed.

“This is the first large clinical trial to support the amyloid hypothesis,” said Lynn Kramer, M.D., chief clinical officer of the neurology business group at Eisai, the Japanese company that developed the drug along with Massachusetts-based Biogen.

But there have been questions about the research methodology, and further clinical trials may be needed to better assess the drug’s potential. Some experts cautioned against hyping the study’s results, as the research on Alzheimer’s drugs is littered with promising failures.

“I would not say shock and awe,” Dr. Julie Schneider told the Associated Press. A professor of pathology at Rush Medical College in Chicago, she added, “It’s encouraging to see some cognitive effect and slowing of disease progression, but I personally think there is a lot more work to be done.”

The trial involved 856 patients from the U.S., Europe and Japan who were diagnosed with either mild cognitive impairment or mild Alzheimer’s dementia. All of them had significant accumulations of the amyloid protein plaques associated with the disease.

Of the 161 patients taking the highest dose of the new drug, more than 80 percent showed significant drops in amyloid levels, and cognitive decline that was 30 percent slower than patients receiving a placebo.

Kramer told the AP that Eisai and Biogen had reached out to regulators in the United States, Europe and Japan to discuss results and next steps. The company has said it hoped to obtain accelerated approval for the next phase of clinical trials.