Vitamin B12 deficiency may be strongly associated with poor cognitive performance in the elderly, a new US study suggests.
In the study, blood vitamin B12 concentrations and markers of vitamin B12 deficiency, such as homocysteine, were measured in 121 adults over the age of 65 (1). The participants took several cognitive tests and about four years later, their total brain volume was measured. The study results showed that participants with a vitamin B12 deficiency were more likely to have lower brain volumes and cognitive impairment than those with adequate vitamin B12 concentrations. In addition, increased levels of four out of five markers of deficiency were strongly associated with poor overall cognitive performance and, more specifically, poor episodic memory and perceptual speed. Moreover, brain volume was significantly lower in those with high levels of markers for vitamin B12 deficiency.
The researchers concluded that insufficient vitamin B12 intake or low B12 concentrations in the body would be a potential risk factor for brain atrophy and may be linked with cognitive impairments. Adequate levels of vitamin B12 would be necessary for the proper functioning of the brain's myelin sheath, an insulating layer around nerves. When the sheath is damaged, impulses transmitted along nerve cells slow down, thus negatively impacting thinking and memory. They suggested that vitamin B12 deficiency may impact cognition by reducing brain volume and/or by the buildup of markers, like homocysteine, which may damage the brain. The scientists recommended taking two to six micrograms of vitamin B12 a day.
The study supports other research showing an association between the B vitamin and cognition. A recent study found that treating patients with a supplement containing vitamins B6, B12 and folate slowed brain atrophy in adults with mild cognitive impairment. Currently, vitamin B12 is not measured in a standard blood workup, and research suggests that testing blood levels of the vitamin may not be an accurate way of detecting a deficiency if scores fall into a gray zone. Thus, the researchers looked at markers of deficiency. People over 65 in particular need increased intakes of vitamin B12 because the elderly do not absorb the vitamin well.