Biogen Inc on Wednesday published long-awaited results of studies supporting approval of its Alzheimer's drug in a lesser-known medical journal whose editor was a leader on the research, adding controversy to the already troubled treatment.

The data on the drug Aduhelm - the first treatment for the mind-wasting disease to win U.S. approval in 20 years - was published in the Journal of Prevention of Alzheimer's Disease, for which Dr. Paul Aisen, who is also a second author on the studies, serves at editor-in-chief.

The company has been under pressure to publish its results to allow the wider scientific community to view the data. Biogen presented the studies earlier on Wednesday at an Alzheimer's meeting in Barcelona.

"It has always been our intention for our Phase 3 data to be peer-reviewed to provide physicians with a greater understanding of the appropriate use of Aduhelm, and we have worked urgently to that end," Biogen spokeswoman Ashleigh Koss said in an emailed statement.

She declined to comment on why the study was published in a lesser-known journal associated with one of its study authors.

Aisen in an email said he was not involved in the review of the research or the decision to publish, details that are listed in the disclosure section of the research paper.

Biogen's Aduhelm has been embroiled in controversy since the U.S. Food and Drug Administration granted it accelerated approval even after its expert panel of outside advisers recommended against it, saying there was not enough evidence of patient benefit.

The limited data released earlier showed that only one of Aduhelm's two pivotal studies demonstrated a slowing of cognitive decline.

In an unusual move, the U.S. Centers for Medicaid and Medicare Services (CMS), which runs the government health plan for people age 65 and older, in January proposed only paying for the drug for patients enrolled in approved clinical trials, a move that would severely limit patient access.

Patient groups have been lobbying CMS to change the policy, which includes similar drugs in development, saying it will delay Alzheimer's treatment for most people for many years.

Biogen on Wednesday said patients enrolled in its Aduhelm trials experienced reductions in two substances linked to the memory-robbing disease after nearly two and a half years of treatment.

The company said Aduhelm "significantly reduced" amyloid beta plaque levels out to week 132 of treatment and also decreased plasma levels of a protein called p-tau181 at week 128.

The company said patients who at week 78 of the trial had shown reduced levels of plasma p-tau181 had less clinical decline in the extended trial than those whose plasma p-tau181 levels were not reduced earlier on.

Amyloid-beta and tau make up the plaques and tangles in the brain that are a hallmark of Alzheimer's disease. Critics have said approval should be based on demonstrable patient improvements or slowing of cognitive decline rather than reductions of such secondary markers.

BMO analyst Evan David Seigerman in a research note called the data "minimally incrementally positive," but said it was not likely to sway the government's coverage plan.

Patient advocacy groups argue that new treatments for Alzheimer's are desperately needed. The number of Americans with Alzheimer's is expected to rise to 13.8 million by 2050 from more than 6 million currently.