NEW YORK — Vitamin E can help slow the effects of mild to moderate forms of Alzheimer’s disease, a finding doctors should consider for treating patients, researchers said.

Patients given high doses of vitamin E for about two years delayed progression of the degenerative brain disease by about 6.2 months, compared with those given a placebo, according to a study published Tuesday in the Journal of the American Medical Association. Doctors may want to discuss vitamin E as an option in early-stage Alzheimer’s treatments, the researchers said.

Vitamin E acts like an antioxidant, which may prevent or delay cell damage, and boost the immune system. The new study builds on findings that showed vitamin E seemed to slow disease progression in patients with moderately severe Alzheimer’s and is the first to show it may help stall functional decline in those with milder forms, said Maurice Dysken, the lead author.

“A delay in six months over two years, that’s very meaningful to some patients and caregivers,” Dysken, a professor of psychiatry at the University of Minnesota, said in a Dec. 27 telephone interview.

Dysken, who is a former director of the Geriatric Research, Education and Clinical Center at the Minneapolis VA Health Care System, added that his study “does not address whether vitamin E will prevent Alzheimer’s disease in people who don’t have the diagnosis.”

The study looked at 613 veterans who were given vitamin E, a combination of vitamin E and Forest Laboratories’ Namenda for moderate to severe Alzheimer’s, Namenda alone or placebo. The vitamin E used in the study was about 20 times greater than the dosage usually found in a multivitamin.

All patients in the trial were on some type of Alzheimer’s medication.

The main outcome was how well patients could perform activities of daily living.