August 2013

High Homocysteine Levels Linked To Reduced Cognitive Function

A recent study suggests that high levels of homocysteine in the blood may be associated with a higher risk of cognitive impairment in older people.

Homocysteine is a naturally occurring, sulfur-containing amino acid in the blood that requires enzymes, vitamin B12, folic acid, and other vitamins to be converted to the essential amino acid methionine. Deficiencies in folic acid (folate), vitamin B6, vitamin B12, or betaine may lead to hyperhomocysteinemia, a medical condition characterized by high levels of homocysteine in the blood. The concentration of homocysteine in the blood will decrease after appropriate supplementation with the deficient vitamins.

In a recent study, researchers from the University of Western Australia and Royal Perth Hospital recruited 358 people over the age of 50 to determine if homocysteine levels may be associated with cognitive impairment in older adults with depressive symptoms. About 70 percent of the participants met the criteria for major depression. The researchers collected blood samples to determine levels of homocysteine, vitamin B12, and folate, and administered cognitive tests to assess verbal and visual recall and memory.

The researchers found that people who had major depression and high homocysteine levels performed significantly worse on the cognitive tests. Participants who had high homocysteine levels without major depression had lower scores than those with normal homocysteine levels. Furthermore, those with high homocysteine levels were almost twice more likely to show cognitive decline on several tests.

The researchers concluded that high blood levels of homocysteine may be linked to weaker performance on cognitive tests, compared to normal levels, independent of the presence or severity of depressive symptoms. The authors suggested that B-vitamin supplementation may be an effective way to lower homocysteine levels and reduce the impact of cognitive deficits in older adults.

For more information about cognitive impairment or hyperhomocysteinemia, please visit Natural Standard's Medical Conditions database.

For more information about B vitamins, please visit Natural Standard's Foods, Herbs & Supplements Database.


  1. Ford AH, Flicker L, Singh U, et al. Homocysteine, depression and cognitive function in older adults. J Affect Disord. 2013 Aug 5. pii: S0165-0327(13)00565-X. doi: 10.1016/j.jad.2013.07.012. 
  2. Natural Standard: The Authority on Integrative Medicine. 

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