TUESDAY, April 15 (HealthDay News) -- Alzheimer's patients who consume very high levels of vitamin E seem to live longer than those who do not, new research suggests.

The study comes on the heels of growing concerns regarding the safety and efficacy of giving any patient -- whether suffering from Alzheimer's or another illness -- the high dosage in question: 2,000 international units (IUs) per day.

"The concern is that vitamin E will actually have a harmful affect, because a recent review of prior studies found that it had a slightly negative impact on mortality," said study author Valory Pavlik, an associate professor with the Alzheimer's Disease and Memory Disorders Center at Baylor College of Medicine in Houston.

"But I think -- to our surprise -- the message really is that for the treatment of Alzheimer's in clinical practice, we did not find evidence that high doses of vitamin E reduced survival," she said. "In fact, patients who took vitamin E seemed to live longer, particularly when they took it in combination with a cholinesterase inhibitor."

Pavlik and her colleagues were expected to present their research Tuesday at the American Academy of Neurology meeting in Chicago.

Their findings stem from almost 15 years spent tracking survival rates among 847 men and women already diagnosed with various stages of Alzheimer's.

Just over two-thirds of the patients were women, and the average age was almost 74. On average, patient outcome was followed for about five years.

About two-thirds of the patients had been prescribed two daily doses of 1,000 IUs of vitamin E, in conjunction with an Alzheimer medication from the class of drugs known as cholinesterase inhibitors.

Cholinesterase inhibitors are designed to halt the breakdown of the neurotransmitter acetylcholine, which is key to nerve pulse function in the brain. Alzheimer's patients suffer from a drop in acetylcholine production, so this class of drugs prevents the otherwise normal elimination of excess transmitters among those who have none to spare.

Fewer than 10 percent of patients took just vitamin E, while about 15 percent took neither the vitamin nor the medication.

The researchers found that patients who consumed the prescribed daily dosage of vitamin E appeared to extend their life span by 26 percent, compared with those not taking vitamin E.

The finding took into account age, gender, years of education, race, ethnicity, co-morbidities and severity of dementia at the start of the study.

Though there were some preliminary indications that the enhanced survival benefit associated with vitamin E was even greater among patients taking both the vitamin and a cholinesterase inhibitor, Pavlik and her team noted that the 26 percent bump held up even without the Alzheimer's drug.

However, those taking a cholinesterase inhibitor alone did not appear to gain any survival benefit.

"Much more research needs to be devoted to the effects of vitamin E on Alzheimer's patients," said Pavlik. "But for now, the door should not be closed on the option".

She pointed out, however, that although 2,000 IUs of vitamin E was the standard supplementary dosage of vitamin E given to Alzheimer's patients during the study period -- from 1990 through 2004 -- such high levels are no longer considered for routine therapy, as a result of studies suggesting that such a dosage might carry unwarranted health risks.

She also stressed that consumption of such high amounts of vitamin E on a daily basis has never been appropriate for the average person.

Eric J. Hall, president and founding CEO of the Alzheimer's Foundation of America in New York City, described the finding as "interesting" and worthy of continued investigation.

"I think the medical community is very open to the possibility that natural ingredients -- therapies outside the realm of FDA-approved drugs, if you will -- can be very helpful to treatment," he said. "For example, everyone agrees that socialization and cognitive stimulation, while neither drugs nor supplements, are important ingredients in Alzheimer's therapy, and almost constitute a kind of treatment."

"But of course," Hall added, "I'm aware that vitamin E, specifically, has come under fire in the last few years, and that there is concern about the possible dangers of taking too high a dosage. So, I think we have to be careful. And probably more research is necessary to find out how vitamin E might be useful in treatment."

Another study presented at the meeting found that people who had larger hippocampuses were spared the ravaging symptoms of Alzheimer's disease.

"This larger hippocampus may protect these people from the effects of Alzheimer's disease-related brain changes," study author Dr. Deniz Erten-Lyons, with the Oregon Health and Science University in Portland, said in a statement. "Hopefully, this will lead us eventually to prevention strategies."

More information

For more on Alzheimer's and treatment therapies, visit the U.S. National Institute on Aging.