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Vitamin B deficiency may cause cognitive impairment
Getting your vitamins may be even more important than previously realized. Researchers have found a link between deficiency of three B vitamins and cognitive impairment, providing new insight into the mechanisms that may underlie age-related cognitive decline.
The research “may provide a model system in which to study the role of the brain’s microvascular circulation in cognitive function,” says Aron Troen. Photo: Stephen Ausmus
Researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) used an experimental model to examine the effects of dietary B vitamin deficiency on metabolic, cognitive and microvascular functions.
“Impairments induced by a diet deficient in three B vitamins—folate, B12 and B6—caused cognitive dysfunction and reductions in brain capillary length and density in our mouse model,” says Aron Troen, a scientist at the HNRCA and the study’s lead author.
Mice fed a diet deficient in folate and vitamins B12 and B6 showed significant shortcomings in spatial learning and memory compared with normal mice, according to Troen, an assistant professor at the Friedman School of Nutrition Science and Policy.
The study, he says, helps define more precisely the mechanisms underlying cerebral microvascular disease, “regardless of the onset of irreversible neurodegeneration.” According to Troen, this work, which was funded by the U.S. Department of Agriculture, “may provide a model system in which to study the role of the brain’s microvascular circulation in cognitive function.”
Troen and colleagues divided their study mice into three groups and fed each group a different diet for 10 weeks. The control group was fed a normal diet containing B vitamins, while the other two diets were deficient in B vitamins.
Researchers measured psychomotor functions using a battery of age-sensitive tests, such as holding on to a wire and walking a beam, and assessed spatial learning and memory with the Morris water maze, in which the mice swim in a container to a platform that allows them to leave the water. At the same time, the researchers measured blood concentrations of B vitamins and assessed the brain anatomy and vasculature.
“It took longer, on average, for the B vitamin-deficient mice to maneuver the water maze, compared with the controls,” says Troen. Longer efforts were associated with higher levels of plasma homocysteine, a chemical implicated in cognitive declines, and shorter capillaries, particularly in the brain region called the hippocampus.
“The elevated levels of homocysteine that were associated with vascular cognitive impairment in the mice in our study are comparable to the levels that are associated in older adults with an increased risk for Alzheimer’s disease and cerebrovascular disease,” such as stroke and atherosclerosis, says Irwin H. Rosenberg, University Professor and director of the Nutrition and Neurocognition Laboratory at the HNRCA.
Despite the vascular changes, the brain anatomy appeared normal, and there was no evidence of a cellular proliferation process that typically accompanies neurological degeneration.
The findings appeared in a recent issue of Proceedings of the National Academy of Sciences (PNAS).
