B-vitamin deficiency linked to Alzheimer’s disease
Posted Nov 21 2008 4:29pm
B-vitamin deficiency may be responsible for vascular cognitive impairment, according to a study published in Proceeding of the National Academy of Sciences.
The research on mice showed that a diet lacking in B-vitamin resulted in lower levels of cognitive ability. The research is significant because it reveals an association between levels of homocysteine (an amino acid found in the blood) and Alzheimer’s disease and cerebrovascular disease.
Irwin Rosenberg, MD, director of the Nutrition and Neurocognition Laboratory at the HNRCA of Tufts explained: “The elevated levels of homocysteine that were associated with vascular cognitive impairment in the mice in our study are comparable to the levels that are associated in older adults with an increased risk for Alzheimer’s disease and cerebrovascular disease, the latter of which manifests with conditions such as stroke and atherosclerosis. These findings may indicate that microvascular changes mediate the association between high homocysteine levels and human age-related cognitive decline.”
Around 26.6 million people worldwide are afflicted by Alzheimer’s. The impact of the disease on cognitive function is significant, with early symptoms including memory loss of recent experiences, and manifestations of stress. Many different measures including mental stimulation, exercise, and a balanced diet have been suggested for the prevention of Alzheimer’s disease, but the degree of their value uncertain. This research however, extends the medical world’s understanding of the disease.
Aron Toen, PhD and leader of the study said: ”Metabolic impairments induced by a diet deficient in three B-vitamins -folate, B12 and B6- caused cognitive dysfunction and reductions in brain capillary length and density in our mouse model. The vascular changes occurred in the absence of neurotoxic or degenerative changes.”
In the study, three groups of mice were fed three different diets for 10 weeks, during which time vitamin homocysteine levels were measured. The cognitive function of the mice was assessed by their ability to navigate their way through a maze. The study showed the B-vitamin deficient mice took longer to complete the maze compared with the non-deficient group. The higher levels of homocysteine measured in the vitamin deficient mice was directly linked with their cognitive ability to complete the task. Folate vitamin B12 and vitamin B6 were then used to reduce levels of homocysteine.
This amino acid is also implicated in cardiovascular disease, and bone weakness. It is strongly suggested that diet influences blood homocysteine levels. Folic acid, vitamins B6 and B12 are documented to help breakdown levels of homocysteine. Higher levels are also associated with greater risks of fatal coronary heart disease and stroke.