Poor vitamin B-12 status leads to reduced brain volume and cognitive decline

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 Many people are aware that vitamin B12 status declines during aging, as millions of seniors fall prey to a decline in this critical nutrient. Vitamin B12 circulating in the blood declines in the elderly due to absorption problems in the digestive tract leading to poor uptake by body tissues, especially the brain. Researchers publishing in the journal Neurology have established a definitive link between poor vitamin B12 levels and brain shrinkage, a hallmark of cognitive decline and Alzheimer's dementia. Supplementation with the biologically active form of the B vitamin may help prevent shrinkage and preserve learning capabilities and memory functions as we age.

The study involved 121 participants from the Chicago Health and Aging Project who underwent magnetic resonance imaging (MRI) scans for over a period of four and a half years. Additionally, each member of the study had blood drawn to measure levels of vitamin B12 and B12-related markers that can indicate a B12 deficiency. The same subjects took tests measuring their memory and other cognitive skills.

Vitamin B12 Deficiencies Linked to Shrinking Brain Volume and Cognitive Decline Among Elderly
MRI scans were analyzed to measure total brain volume and to look for other signs of brain damage. The tests included seven measures of episodic memory, two measures of visual spatial ability and perceptual organization, two measures of perceptual speed, two measures of semantic memory, and three measures of working memory. Stored blood samples were analyzed for vitamin B12 and homocysteine, a byproduct of metabolism associated with dementia, cognitive decline and coronary artery disease.

Researchers determined that having high levels of four of five markers for vitamin B12 deficiency was associated with having lower scores on the cognitive tests and smaller total brain volume. Indicators of vitamin B12 insufficiency contributed to poor global cognitive test scores and a decrease in brain volume revealed by MRI findings compared to those with better B12 status. Higher levels of the vitamin B12 markers were linked to decreased total brain volume. Elevated homocysteine levels were indicative of greater white matter volume and elevated risk of cerebrovascular events.

Lead researcher, Dr. Christine Tangney concluded "Our findings suggest that ... vitamin B12 deficiency, may affect cognition by reducing total brain volume whereas the effect of homocysteine on cognition may be mediated through increased white matter hyperintensity volume and cerebral infarcts." Vitamin B12 deficiency among the elderly is a significant cause for concern and may very well be a key contributor to the explosion of Alzheimer's disease cases over the past 50 years. Nutritionists recommend supplementing with the bioactive form of B12 known as methylcobalamin (1 to 5 mg per day taken sublingually) to regulate circulating levels of this critical brain nutrient.