By James Meschino, DC, MS

The results of several research studies suggest that consuming adequate amounts of folic acid, vitamin B₆ and vitamin B₁₂ throughout one’s lifetime may play a key role in reducing the risk of developing Alzheimer’s disease and other types of dementia as we age. This evidence was further strengthened by a recent British study that found a group of patients with Alzheimer’s disease had higher blood levels of homocysteine than members of the age-matched control group who were not afflicted with Alzheimer’s disease. Individuals with higher blood levels of homocysteine were several times more likely to have Alzheimer’s disease than those with lower blood homocysteine levels. The average age of the subjects in this study was 75.

The strongest determinant of blood homocysteine levels (unless there is an overriding genetic defect of some major consequence) is the nutritional status of folic acid, vitamin B₆ and vitamin B₁₂. These same B vitamins are also involved in the synthesis of important neurotransmitters that are required for cognitive function and other brain functions. Currently, the average intake of folic acid is only about half of the 400 mcg that experts indicate should be the daily recommended intake level for otherwise healthy individuals.

A significant number of individuals over the age of 60 don’t absorb vitamin B₁₂ efficiently from food sources due to changes in their digestive tract. Many authorities encourage consumers to ingest more dark-green vegetables, beans and fortified grains to acquire folic acid and fortified cereals to help acquire additional vitamin B₁₂. The Tufts University Health & Nutrition Letter also suggests that taking a daily multiple vitamin and mineral is another way to ensure that patients achieve a more optimal intake of these B vitamins. This may be a simple but important measure to prevent changes in brain function related to the development of Alzheimer’s disease and dementia.¹

Preventing Age-Related Mental Decline

The notion that deterioration in mental capacities is a natural part of the aging process has been challenged by the findings of a number of recent research studies that indicate vitamin and mineral status may be significant factors in modifying a person’s risk of developing Alzheimer’s disease and other types of cognitive impairment and dementia. Riggs and associates published findings that indicated older individuals with low blood concentrations of vitamin B₁₂, vitamin B₆ and the B vitamin known as folic acid had the poorest scores of brain function, as measured by a battery of cognitive tests.²

In previous studies, clinical deficiencies of B vitamins have been implicated in brain-related disorders, including reversible dementia (vitamin B₁₂ and possibly folate), depression (folate) and electrophysiological dysfunction, including convulsions (vitamin B₆).^3-5 In healthy older adults, blood levels of B vitamins usually considered to be in the normal range were associated with poorer scores on tests of delayed recall, abstract reasoning and selective attention.^6,7 There is also good evidence that deficiencies of vitamin B₁₂, folic acid and vitamin B₆ increase with age and are common in older adults.^8,9 Thus, there is growing support for the premise that optimal B vitamin status can prevent, slow or reverse the deterioration in memory and other mental capacities important to quality of life issues in older individuals.

The Normative Aging Study

The Normative Aging Study involved 70 male subjects, ages 54 to 81. The results of this study revealed that blood levels of vitamin B₁₂ and folic acid appear to be related to cognitive performance in a different manner than vitamin B₆ blood levels.² Low blood levels of vitamin B₁₂ and folic acid were associated with deficits in spatial copying. Higher blood levels of vitamin B₆ were associated with better performance on two tests of memory. Another interesting finding was that nearly one half of the subjects in this study had low blood levels of vitamin B₆ (<30 umol/L).¹⁰

This study is extremely important because B vitamins are known to participate in brain chemistry and physiology. Vitamins B₁₂ and folic acid are required as co-enzymes in the synthesis of the neurotransmitters, serotonin catecholamines (adrenaline, norepinephrine). They are also required for the production of S-adenosylmethionine, which has antidepressant properties.^11-13 Vitamin B₁₂ deficiency may also result in de-insulation of nerve fibers (demyelination), which produces a constellation of neurological symptoms.⁵ Vitamin B₆ is a co-factor in the production of other brain chemicals (neurotransmitters) including dopamine, norepinephrine, serotonin, gamma-aminobutyric acid (GABA) and taurine.¹⁴

Higher blood levels of homocysteine also often result from subnormal intakes of folic acid, vitamin B₁₂ and vitamin B₆. This is because these vitamins are required to recycle homocysteine to other amino acids such as methionine and cystathionine.¹⁵ High blood levels of homocysteine are associated with increased risk of cardiovascular, cerebrovascular (narrowed arteries in the brain), and peripheral vascular disease (narrowed blood vessels in the arms, hands, legs and feet).¹⁶ Narrowed arteries in the brain (cerebrovascular disease) have been shown to be associated with decrements in psychomotor speed and on tests measuring fluid and visual abilities.^17-21 Such cognitive dysfunction, therefore, may stem from high levels of homocysteine. As previously stated, vitamins B₆, B₁₂ and especially folic acid are key nutrients that prevent and reverse high blood levels of homocysteine.

In the Normative Aging Study, subjects with high levels of homocysteine performed, on average, like patients with mild Alzheimer’s disease.² They also exhibited difficulty in copying the most complex spatial figures. For example, few subjects in the highest 25 percent range of homocysteine concentrations completed the cube (22 percent) and tapered box (17 percent) correctly. By comparison, these figures are mastered by 50 percent of school children by the age of 13. Subjects with the lowest blood homocysteine levels demonstrated the best results on these tests.

Supplement Support

Taken together, the body of evidence continues to support the contention that B vitamin nutritional status is crucial to the development and preservation of mental capacities throughout our lifetime. The sad reality is that many midlife and older members of society have poor dietary intake and nutritional status of various B vitamins (vitamin B₆, folic acid, etc.). By all counts ,it appears that health practitioners should encourage patients to pay attention to foods that are rich sources of these important B vitamins and to continue to emphasize the multitude of benefits available from the daily use of a well-formulated multiple vitamin and mineral supplement.

Dr. James Meschino graduated from Canadian Memorial Chiropractic College and practices in Toronto. He is an associate professor at CMCC and has participated as a guest lecturer at Ryerson University and the Canadian College of Naturopathic Medicine. Dr. Meschino can be contacted via his Web site, www.renaisante.com.