An important study appeared in JAMA Psychiatry in June 2016, providing additional evidence that high blood levels of Vitamin B12 can slow the shrinking of the brain that commonly occurs after age 60. Previous studies have shown that vitamin B12 and other B vitamins can slow the rate of brain atrophy in older subjects with mild cognitive impairment and decrease the risk of progression to Alzheimer’s disease. Overall, the emerging scientific evidence suggests if you can slow or prevent the shrinking of the brain, which is common after age 60, you may decrease your risk of dementia and Alzheimer’s disease quite substantially.
B12 is needed to make a number of brain neurotransmitters and has been shown to have neuroprotective effects, which may directly slow brain shrinking. It also lowers a chemical in the blood called homocysteine. High homocysteine is known to be extremely damaging to the brain and cerebrovascular blood vessels, and high blood levels of homocysteine are strongly correlated with brain atrophy and risk of Alzheimer’s disease in many studies.
In the JAMA Psychology study, higher homocysteine also was linked to more rapid brain volume shrinkage. So, there are at least two ways by which vitamin B12 may slow brain shrinking-by directly preventing loss of brain cells and by lowering homocysteine blood levels.
According to studies, B vitamin supplementation slowed brain atrophy by 30 percent, on average, and in some cases up to 53 percent. Cognitive tests showed that the greater the rate of brain atrophy, the more rapid the decline in cognitive function.