Our bodies are unable to synthesize Vitamin B12 on their own, and instead rely on foods such as meat, dairy, eggs and fish as a source. Once absorbed, vitamin B12 circulates and is converted into a variety of different important metabolites, depending on the needs of the body at that time. One of these metabolites is methylcobalamin, a version of vitamin B12 that has a small chemical group attached to it. Methylcobalamin plays a large role in nearly all aspects of metabolism in the body. To put this into perspective, it has been linked to processes that directly alter DNA and gene expression, and regulation of brain activity such as attention. It is well known that vitamin B12 is required in our daily lives, however there hasn’t been a study until now that looks at differences in vitamin B12 in the brain relating to age and disease. Since Vitamin B12 metabolites have been linked to diseases that affect the brain such as schizophrenia and Alzheimer’s disease, the Deth group at Northeastern University in Boston set out to study whether changes in B12 metabolite levels correlate with age and disease.
For this study, samples from brains of 64 patients ranging in age from 0-80 years old were used to measure levels of vitamin B12 and its metabolites. This was carried out using a process called High Performance Liquid Chromatography (HPLC). Simply put, this process separates the different metabolites based on slight differences in how they interact with a material lining a column. This way, the levels of each metabolite can be studied separately and changes between them will be more apparent. Using HPLC, the Deth group found that the overall levels of all types of Vitamin B12 in the brain were 2.7 times lower in 60-80 age group in compared to that of 0-20 year olds. However, overall levels of Vitamin B12 in the rest of the body showed no change with age. In addition to this, there was a clear age-dependent decline in methylcobalamin specifically, with 60-80 year olds showing 12 times less than 0-20 year olds!
Another interesting finding in this study was that the overall levels of Vitamin B12 in the brains of autistic and schizophrenic subjects were each 3 times lower than control subjects of the same age. For an unknown reason, these diseased brains show signs of aging through Vitamin B12 deficiencies that match those of subjects 60-80 years old.
Because the changes in Vitamin B12 levels in the brain are specifically affected with age but changes in the rest of the body have not been observed, there may be a defect in transporting this vitamin to the brain as we get older. This deficiency of Vitamin B12 in the brain may contribute to neurological disorders such as autism and schizophrenia.
 Zhang, Y., Hodgson, N.W., Trivedi, M.S., Abdolmaleky, H.M., Fournier, M., Cuenod, M., Do, K.Q., and Deth, R.C. (2016). Decreased Brain Levels of Vitamin B12 in Aging, Autism and Schizophrenia. PLoS One 11, e0146797.