Dr. Ernst J. Schaefer, of Tufts University, Boston and colleagues examined associations between blood DHA levels and dementia risk in 899 men and women free of dementia at entry into the Framingham Heart Study. They had their blood fatty acids measured at an average of 76 years old.

After 9.1 years of follow-up, 99 subjects had developed dementia. Seventy-one of the cases were classified as Alzheimer's disease.

After controlling for other risk factors for dementia including age, gender, genotype, and elevated homocysteine, the team found that men and women with the highest DHA levels had a 47 percent reduction in risk of developing dementia and a 39 percent reduction in the risk of Alzheimer's disease compared with those with less DHA.

Schaefer stated that the high level was probably achieved by consuming more than 2.8 fish meals per week or about 180 milligrams DHA per day. DHA can also be obtained in fish oil capsules, and one capsule usually contains about this amount."

"Our data suggest that increased blood levels of DHA due to increased fish intake cuts the risk of developing dementia by almost 50 percent," Dr. Schaefer said. However the findings need to be verified by additional trials, trials.

In an accompanying editorial, Dr. Martha Clare Morris of Rush University Medical Center, Chicago calls the study "an important contribution to a young field of study on diet and neurodegenerative diseases." She also notes that there is a "strong biological basis for the association of DHA and neuroprotection."

SOURCE: Archives of Neurology, November 2006.