In one of those studies, at the University of California, Irvine, scientists used genetically engineered mice and it is reportedly the first to show that an omega-3 fatty acid known as docosahexaenoic acid, or DHA for short, can slow the accumulation of tau, a protein that leads to plaque and tangles in brain tissue seen in Alzheimer's.
DHA, which is found in foods like eggs and fish, was also found to reduce levels of another protein -- beta amyloid -- which can clump in the brain and form the characteristic plaques that lead to symptoms like memory loss.
The study appears today in the Journal of Neuroscience.
Lead researcher Kim Green, a UC-Irvine scientist, said the study proves there are practical things people can do now to help delay onset of the disease, although a cure for Alzheimer's may still be years away.
Funded by Martek Biosciences Corp. in Columbia, Md., the study also adds to the growing body of evidence that diet and lifestyle changes may reduce the risk of disease development.
"It is very, very safe for humans," Green said of DHA, noting the supplement is even used in baby foods because it is vital for brain development.
Green and his team, which included co-author and neurobiologist Frank LaFerla, fed mice in a control group food that mimics a typical American diet, with the ratio of omega-6 fatty acids to omega-3 fatty acids being 10:1.
Omega-6 fatty acids are found in foods like corn, peanut and sunflower oils. Studies have indicated that a healthy ratio of these fatty acids is about 3:1 to 5:1. Typical western diets, however, contain substantially less than that.
The mice were divided into different groups and given food with a 1:1 ratio of the fatty acids. After three months, all of the mice had lower levels of the bad proteins - beta amyloid and tau - than mice in the control group that were fed the American diet.
But at nine months, only the mice that received supplemental DHA alone had lower levels of both bad proteins.
"The relatively simple changes in diet through supplements with DHA, omega-3 fatty acid works," Green said. "Combined with mental stimulation, exercise, other dietary intakes and avoiding stress and smoking, we believe that people can significantly improve their odds against this disease," he added.
The Purdue study, to be published May 3 in the Journal of Medicinal Chemistry, is funded by the National Institutes of Health, National Institute on Aging. It is based on scientific belief that there are enzymes in the brain responsible for causing beta amyloid to accumulate and eventually form the clumps that lead to plaque development.
Specifically, a key enzyme known as memapsin 2, or beta-secretase, involved in development of Alzheimer's disease, could be blocked by the newly discovered molecule, or inhibitor compound, thereby preventing the disease.
"It stopped the formation of this protein up to 30% in a single dose in the mice model. This is a significant result," said Arun Ghosh, a Purdue professor of chemistry who designed the molecule.
Many pharmaceutical companies are now working on developing similar compounds, called secretase inhibitors, aimed at blocking the activity of brain enzymes that lead to the accumulation of amyloid, key to Alzheimer's disease development.
"Scientists are trying to strike a balance between blocking amyloid accumulation to prevent or halt the progression of Alzheimer's, but not in a way that interferes with healthy brain functioning," said William Reichman, a professor of neurology and psychiatry at the UMDNJ-Robert Wood Johnson Medical School in New Brunswick.
He called both studies exciting, although he cautioned that the work on DHA supplementation is still very much "experimental."
"We don't recommend it yet," he said.
From the April 23, 2007, Prepared Foods e-Flash