Scientists said that faulty variations of the SORL1 gene resulted in changes in the level of a protein that contribute to buildup of amyloid plaques, a hallmark sign of Alzheimer's in the brains of people with the disease.

In total, 29 variations of the gene were identified that may cause the disease, but the researchers did not know which variations are responsible for Alzheimer's.

In the study, Richard Mayeux of Columbia University and colleagues from Boston University and the University of Toronto in collaboration of 14 institutions in North America analyzed genetic variations in 6,000 individuals who donated blood samples.

"We do not fully understand what causes Alzheimer's disease, but we know that genetic factors can play a role," said Richard J. Hodes, M.D. director of National Institute on Aging.

"Scientists have previously identified three genes, variants of which can cause early onset Alzheimer's, and one that increases risk for the late onset form. This discovery provides a completely new genetic clue about the late onset forms of this very complex disease. We are eager to investigate the role of this gene further," he said.

The scientists believed that the processing of amyloid precursor protein or APP into amyloid beta protein fragments that make up plagues in the brain in the Alzheimer's patients.

Among the seven genes initially searched that are involved in moving APP within cells, the scientists found that many families with a history of Alzheimer’s disease had variations in the SORL1, but not consistently in other six genes.

"We are seeing the gene implicated in multiple data sets, across ethnic and racial groups," Lindsay Farrer, Ph.D., of Boston University, one of the lead authors of the study. He adds that the group was "encouraged and excited" by cell biology experiments that demonstrate SORL1's role in production of beta amyloid fragments.

The researchers found that levels of SORL1 protein in Alzheimer's disease was 50 percent lower than that found in people who did not have the disease. Low levels of SORL1 protein resulted in high production of amyloid beta fragments, which form plaques in the brains of Alzheimer’s patients.

But they said other genetic and non-genetic factors are likely to affect production of the SORL1 protein in people.

The finding does not seem to have any immediate application in the prevention or treatment of Alzheimer's disease.   The researchers said more research is needed to determine how different variations of the SORL1 gene influence production of the harmful protein.

In the U.S., about one in twelve people over age 65 have Alzheimer's.   Incidence of the disease has increased so much that it is being referred to as a "20th Century disease," according to Wei Liu and Changzhen Gong of the American Academy of Acupuncture and Oriental Medicine, who said in their article published on http://www.tcmpage.com/hpalzheimer.html that genetics is just one of the factors for degenerative diseases like Alzheimer's.

They said risk factors also include inadequate diets and environmental toxins such as aluminum, lead, and pesticides, which can affect both the brain and the digestive system.   Young people who show symptoms of Alzheimer's may have been affected by their unhealthy diets or environmental toxins.

According to Liu and Gong, refined sugar, dairy products, wheat, deep fried, and high fat foods should be eliminated in the diet to reduce the risk of Alzheimer's disease.

"A lot of foods are great for our memories and reduce the risk of Alzheimer's, such as whole grains, soy products, legumes, fish, brewer's yeast, millet, rice, wheat germ, nuts (especially walnuts), black sesame seeds, pumpkin seeds, and sprouts. These foods are rich in vitamin B, beneficial proteins and many other nutrients. Also, make sure that you eat fruits and lightly-cooked vegetables every day," they wrote in their article.

They also said both amino acids and the B-complex of vitamins such as choline and B6 are important with the former for building protein and the latter for increasing blood circulation, improving memory and lowering cholesterol.

In addition, they suggested people use foods and herbs that are friendly to the kidneys.    What benefits the kidneys are also beneficial to the brain as both organs are related, according to the theory of the traditional Chinese medicine by which Alzheimer's disease can be explained.   These foods include "black sesame seeds, kelp, shiitake and black ear mushrooms."

Beneficial herbs include He Shou Wu (Fo Ti), rehmannia root, ginseng, hyperzia serrata root and ginkgo extract, Yi Ye Chau (Securinega suffruticosa) and Fan Hong Hua (Crocus sativa), which may also have a positive effect on Alzheimer's disease by promoting vasodilation and blood flow.

They pointed out that the simple way to minimize the risk of Alzheimer's or other similar diseases is to keep physically and mentally active.