Dr. Douglas R. Galasko of the University of California, San Diego, and colleagues examined changes in cerebrospinal fluid biomarkers related to Alzheimer disease and oxidative stress, cognition and function.
Oxidative damage in the brain is associated with aging and is widespread in Alzheimer disease patients and some observational studies suggested that an antioxidant-rich diet might reduce the risk of Alzheimer's disease.
The study involved 78 patients from the Alzheimer's Disease Cooperative Study Antioxidant Biomarker study who were divided into one of three groups: 800 International Units/per day of vitamin E, 500 milligrams/per day of vitamin C and 900 mg/per day of alpha-lipoic acid; 400 mg of coenzyme Q 10 three times a day; or placebo. Sixty-six patients provided serial cerebrospinal fluid specimens adequate for biochemical analyses during the 16-week trial.
"This combination of vitamin E, vitamin C and alpha-lipoic acid did not affect cerebrospinal fluid biomarkers such as tau proteins, which are related to Alzheimer disease," the study authors said in a statement.
The antioxidant combination resulted in a lowering of cerebrospinal fluid F2-isoprostane levels suggesting a reduction of oxidative stress in the brain, the researchers said. However, subjects given a brief test of mental status function, showed a more rapid decline.
"It is unclear whether the relatively small reduction in cerebrospinal fluid F2-isoprostane might lead to clinical benefits in Alzheimer disease. The more rapid cognitive decline score raises a caution and indicates cognitive performance would need to be assessed if a longer-term clinical trial of this antioxidant combination is considered," the authors concluded.
The findings published in the Archives of Neurology also found coenzyme Q 10, at the tested dose, did not improve indices of oxidative stress or neurodegeneration.