More from MPR
April 13, 2005
St. Paul, Minn. — People with mild cognitive impairment have trouble forming new memories. It's seen as an early indicator to Alzheimer's disease since it's more advanced than traditional aging, but isn't as advanced as full-blown Alzheimer's.
For the study, the Mayo Clinic's Dr. Ron Petersen split 769 people into three groups. The first group received a sugar pill. The second group received a daily dose of vitamin E, and the third group received a daily dose of the drug Aricept.
Aricept is in a class of drugs called cholinesterase inhibitors, currently prescribed to treat symptoms of Alzheimer's disease. They are designed to enhance memory and other cognitive functions by influencing certain chemical activities in the brain.
Petersen says those who took Aricept were less likely to develop Alzheimer's in the first year of the study.
"We now have demonstrated the ability to intervene at an earlier stage in the mild cognitive impairment Alzheimer's continuum, and push back that clinical diagnosis of Alzheimer's disease -- albeit for a limited period of time," Petersen says. "Nevertheless, we were able to do that and that has not been demonstrated before."
Petersen says the drawback is that those who showed success in the first year of the study ended up getting Alzheimer's in the second or third year of the study. He says either the drug's effect wore off, or the disease took over.
Petersen says he intends to do further research to see if other drugs are more effective on those with mild cognitive impairment.
The other major finding involved the group that took the daily dose of vitamin E. The study reported no benefit.
"The fact that it wasn't helpful in this study is particularly disappointing," says Dr. Deborah Blacker, director of gerontology research at Massachusetts General Hospital in Boston.
Blacker says previous research suggested that vitamin E could delay Alzheimer's, as well as prevent heart disease and cancer. The Nutrition Business Journal says Americans spent $710 million on vitamin E supplements in 2003. But Blacker says Petersen's research and other recent data show that vitamin E isn't that beneficial.
She says one study found that those who took vitamin E supplements are at even higher risk of death than those who don't take it.
"It doesn't look like it helps. It might not be harmless, and it doesn't look like it helps for other things," says Blacker. "I think people really have to consider whether they should stop taking vitamin E for this purpose, and I think they probably should."
But others say patients shouldn't abandon vitamin E altogether. Martha Clare Morris is an associate professor at Rush University Medical Center in Chicago. She published research that found that those who ate foods rich in vitamin E reduced their Alzheimer's risk significantly.
Morris says there's a difference between vitamin E supplements like those used in the study, and foods rich in vitamin E.
"There's good evidence to believe that having adequate vitamin E from food sources may prevent Alzheimer's disease. This clinical trial does not rule out a benefit from food sources for the development of Alzheimer's disease," says Morris.
The Mayo Clinic's Dr. Ron Petersen says further studies need to be done to determine if vitamin E is effective in other forms.
His study was released one day after researchers announced that some antibodies are effective in attacking the protein believed to be responsible for Alzhiemer's. Petersen says the research seems promising, but scientists need to consider every alternative to delay or prevent the disease.
"I think a lot of this is evolving, and we'll try to keep on top of this for the next few years. Incrementally, each study adds to our knowledge about the disease process and possible treatments," says Petersen. "I think it's a very slow process that's moving in the right direction."
Petersen's research was supported by the National Institute on Aging and the two drug companies that co-market the drug, Aricept. It was published in the New England Journal of Medicine.