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According to research funded by the U.S. National Institutes of Health, nearly 25 percent of older adults had small pockets of dead brain cells that may have been caused by unnoticed "silent strokes."

The study, which involved 658 men and women aged 65 and older who did not have history of dementia, found that 174 of the participants had experienced silent strokes and likewise did not perform well on memory tests.

The size of the hippocampus (the part of the brain that controls memory) did not appear to be a factor for the varying degrees of memory loss, said the study.

"Since silent strokes and the volume of the hippocampus appeared to be associated with memory loss separately in our study, our results also support stroke prevention as a means for staving off memory problems," study author Adam Brickman, of the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center in New York, explained in a news release from the American Academy of Neurology as reported by USA Today.  The journal Neurology plans to publish the full results on Jan. 3.

Another study also published by the journal Neurology this week suggested that certain vitamins and a low-trans-fat diet may help preserve memory.

"Trans fats are known to be bad for cardiovascular health, so it's not too much of stretch to think that they're bad for the brain," study author Gene Bowman, an assistant professor of neurology at Oregon Health and Science University said to MSNBC. "It turns out trans fat was actually our most consistent finding in the study."

The researchers found that trans fat (found in fried and many processed foods) contributed to "more shrinkage of the brain" in addition to less cognitive recognition.

However, among the 104 participants in the study 87-years-old (on average) who were ingesting high levels of omega-3 fatty acids and vitamins B, C, D, and E, did better on their cognitive tests, accounting for "over 70 percent of the variation in the scores of cognitive tests taken by the study subjects, the researchers reported," said MSNBC.

"I think it's timely in that we have other studies showing a connection between, for example, overweight or obesity and dementia risk," said Dr. Gary Small, director of the UCLA Longevity Center and co-author of "The Alzheimer's Prevention Program" (Workman Publishing, 2011), to MSNBC. "You can see there is clearly a connection between what we eat and how well we think as we age."