New York: Ageing men with the highest levels of homocysteine, a blood protein linked to degenerative diseases, and lthe owest levels of vitamins B6, B12 and folate experience an increased rate of cognitive brain decline.

Past studies have indicated that elevated levels of the amino acid homocysteine may contribute to cognitive impairment. In addition, past studies have determined that most elevations in homocysteine result from low intake of folate, vitamin B12, or vitamin B6.

The research published in the American Journal of Clinical Nutrition assessed the individual and independent effects of baseline plasma homocysteine, folate, vitamin B12, and vitamin B6 and of dietary B vitamin intakes on 3-year changes in cognitive measures in 321 aging men. At baseline, the subjects’ dietary intakes of B vitamins were determined with a food-frequency questionnaire. In addition, blood was drawn to measure levels of B vitamins and homocysteine.

Over a mean 3-year follow-up, declines in cognitive function were significantly associated with increasing levels of plasma homocysteine, and with low levels of folate, vitamins B6 and B12. A low dietary intake of each vitamin also was associated with cognitive decline. Plasma levels and dietary consumption of folate remained independently protective against two aspects of cognitive decline (including verbal fluency) after adjustment for other vitamins and for plasma homocysteine. A high homocysteine concentration was associated with a decline in recall memory.

According to the study authors, “Low B vitamin and high homocysteine concentrations predict cognitive decline.”