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Lower brain levels of vitamin B₁₂ may indicate aging, autism, schizophrenia

Recent findings indicated vitamin B₁₂ levels in the brain decrease with aging and are lower in individuals with autism or schizophrenia, compared with age-matched healthy controls.

“These are particularly significant findings because the differences we found in brain B₁₂ with aging, autism and schizophrenia are not seen in the blood, which is where B₁₂ levels are usually measured.” Richard C. Deth, PhD, of Northeastern University, Boston, said in a press release. “The large deficits of brain B₁₂ from individuals with autism and schizophrenia could help explain why patients suffering from these disorders experience neurological and neuropsychiatric symptoms.”

Richard C. Deth

To assess vitamin B₁₂ status in the brain across lifespan, researchers measured levels of five cobalamin species in postmortem human frontal cortex samples from 19 weeks fetal development through age 80 years among 12 individuals with autism, nine with schizophrenia, and 43 controls.

Total cobalamin was significantly lower in controls aged older than 60 years, indicating a more than 10-fold age-dependent decline in methylcobalamin levels.

Levels of inactive cyanocobalamin were significantly higher in fetal brain samples, according to researchers.

Levels of methylcobalamin and adenosylcobalamin were more than 3-fold lower in individuals with autism or schizophrenia, compared with controls.

Lower methylcobalamin was associated with decreased methionine synthase activity and increased levels of substrate homocysteine among individuals with autism.

“In conclusion, vitamin B₁₂ levels in human frontal cortex decrease with age, especially [methylcobalamin], which plays a crucial role in regulating all methylation reactions, including those providing epigenetic regulation of gene expression,” the researchers wrote. “[Methylcobalamin] deficits in autistic and schizophrenic subjects suggest that impaired methylation may be a critical pathological component of these brain disorders, as well as other neurological and neuropsychiatric conditions. Our findings provide a novel redox/methylation-based perspective on the metabolic systems which support normal brain function across the lifespan.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.