The brains of the elderly and younger people with autism and schizophrenia may share a common link: Both have low levels of vitamin B12, researchers say.
The facts that blood levels of B12 do not always mirror brain levels of the vitamin, and that brain levels decrease more over the years than blood levels, may imply that various types of neurological diseases — such as old-age dementia and the disorders of autism and schizophrenia — could be related to poor uptake of vitamin B12 from the blood into the brain, the scientists said.
The findings, reported last month in the journal PLOS ONE, support an emerging theory that the human brain uses vitamin B12 in a tightly regulated manner to control gene expression and to spur neurological development at key points during life, from the brain’s high-growth periods during fetal development and early childhood, through the refining of neural networks in adolescence, and then into middle and old age.
In the new study, scientists led by Richard Deth, a professor of pharmacology at Nova Southeastern University in Fort Lauderdale, Florida, examined the brains of more than 60 deceased individuals, ranging in age from a fetus in a late stage of gestation to 80 years. The study included 12 people who had autism and nine with schizophrenia.
This is the first study to compare the levels of vitamin B12 in the brain across the human lifetime, Deth told Live Science. The vitamin B12 levels in the brain were 10 times lower in the oldest people compared with the youngest, reflecting a gradual, natural, and consistent decline over the years.
For the elderly, this decline might not be a bad thing. Lower levels at advanced ages may offer some degree of brain protection by slowing cellular reactions and the production of DNA-damaging chemicals called free radicals, Deth said. In previous work with his colleague Yiting Zhang of Northeastern University in Boston, Deth found that the body’s creation of biologically active forms of vitamin B12 produces free radicals as a waste product.
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