In that B vitamins have been reported to nourish the brain, U.S. Department of Agriculture (USDA) nutritionist Lindsay H. Allen has collaborated in ongoing research that has taken a closer look at the role these nutrients may play in preventing decline in brain function. The investigations, led by Mary N. Haan of the University of California-San Francisco, are part of the multiyear Sacramento (Calif.) Area Latino Study on Aging, or "SALSA." Begun in 1996, the study attracted nearly 1,800 Hispanic seniors, ages 60 to 101, as volunteers. Analysis of subjects’ blood samples showed that lower levels of one B vitamin, folate, were associated with symptoms of dementia and poor brain function, with the impairments detectable even though less than 1% of the subjects were actually deficient in folate. Further, the team found that in women, but not men, low levels of folate were associated with symptoms of depression, such that in female subjects whose plasma folate levels were in the lowest third were more than twice as likely to have symptoms of depression, as compared to counterparts in the highest third.  In research with vitamin B-12, the researchers also found that the protein known as holoTC (holotranscobalamin), might be key to a new approach to detect cognitive decline earlier and more accurately.