ST. PAUL, MN -- Supplementing diets with antioxidant vitamins C and E may boost mental ability in later life and could protect against vascular and some other forms of dementia, according to a study published in the March 28 issue of Neurology, the American Academy of Neurology1s scientific journal.
"We believe antioxidants like vitamin E and C may protect against vascular dementia by limiting the amount of brain damage that persists after a stroke," said study author Kamal Masaki, MD, of the University of Hawaii in Honolulu. "The supplements may also play a role in providing protection against brain cell and membrane injury involved in many aging-related diseases, thus resulting in significantly higher scores on mental performance tests in later life."
The study investigated 3,385 Japanese-American men, aged 71-93, participating in the Honolulu Heart Program, a prospective study of heart disease and stroke initiated in 1965. The men were interviewed or surveyed in 1982 and 1988, and were assessed for dementia and mental abilities during exams in 1991 to 1993. Of the participants, 47 were diagnosed with Alzheimer's disease, 35 with vascular dementia, 50 with other or mixed types of dementia, 254 had low cognitive test scores without diagnosed dementia, and 2,999 men showed no cognitive difficulties.
Participants taking both vitamin E and C supplements regularly (at least once a week) in 1988, were 88 percent less likely to have vascular dementia four years later and 69 percent less likely to have forms of dementia other than vascular or Alzheimer's related dementia or mixed forms of dementia. There was no significant reduction in the occurrence of Alzheimer's disease four years later.
Participants without dementia were evaluated for mental performance and function. Those who reported taking vitamin E and C supplements in 1988 had an approximately 20 percent greater chance of having better cognitive function during the 1991-93 examination than those who did not. However, men taking the supplements in both 1982 and 1988 had an approximately 75 percent greater chance of better mental performance. This suggests that long-term use could significantly improve cognitive function in late life.
"We originally thought that the beneficial impact antioxidant vitamin supplements had against vascular dementia was the prevention of stroke," commented Masaki. "However, to our surprise we found there was not a significant association between vitamin supplement use and clinically recognized stroke."
Previous reports have shown that antioxidants may slow the progression of Alzheimer's disease and the researchers were also surprised when they did not find a protective effect against Alzheimer's. "It is critically important for patients to practice preventive efforts shown to lower stroke risk and to have broad ranging beneficial effects," said Masaki. "More effective strategies for prevention also must be found. Therefore, a prevention trial of both vitamin E and C to further examine the potential protective effects on both vascular dementia and Alzheimer's disease is needed."
Vascular dementia is the second most common cause of dementia in the United States (following Alzheimer's disease) and the most common cause of dementia in Japan. Those with vascular dementia face the physical impairment related to stroke, such as paralysis, and speech, language and visual disturbances, in addition to mental impairment.
The American Academy of Neurology, an association of more than 16,500 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its Web site at http://www.aan.com. For online neurological health and wellness information, visit NeuroVista at http://www.aan.com/neurovista.
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