Vitamin B12 Deficiency: What are the consequences?

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Alzheimer's Disease and its relationship with dementia 

Alzheimer's Disease is the most common form of dementia amongst older people. The disease affects parts of the brain that affect memory and speech. Over 1% of the population is affected with Alzheimer's disease.. 

Whilst the exact cause of Alzheimer's disease is not known it is associated with the build up of neurofibrillary tangles, which can be detected by Magnetic Resonance Imaging (MRI). Diagnosis of AD is hard and the symptoms generally only occur after there has been extensive neurological damage.  As the disease progresses there is a progressive decline in memory and cognitive capacity in affected individuals. Growing evidence suggests that elevated homocysteine is an early marker or predisposing factor for Alzheimer's disease. Elevated homocysteine is inversely correlated with levels of vitamin B12 and possibly folate, suggesting vitamin B12 deficiency as being one of the most important predisposing factors.

Vitamin B12 deficiency and Alzheimer's Disease 

Vitamin B12 helps to maintain healthy nerve cells and blood cells. Several studies have have linked the occurrence of vitamin B12 deficiency with an increased incidence of, or early onset of Alzheimer's Disease and dementia. Studies looking at vitamin B12 levels have found reduced levels of vitamin B12 in the cerebrospinal fluid of AD patients. At least one study has found that intravenous administration of methylcobalamin can improve mental functions such as memory, emotional function and communication with other people*. High doses of vitamin B12 have been shown to reduce the rate of shrinkage of the brain in those over 60. This shrinkage is reported to be part of the process in the development of Alzheimer's disease. High dose supplementation of vitamin B12 for Alzheimer's disease has potential in delaying the development of Alzheimer's disease.

Treatment of Vitamin B12 deficiency and Alzheimer's disease

By the time a patient develops Alzheimer's disease, there has been significant damage to the neurones and vitamin B12 is severely depleted in the liver, but more importantly in the brain and CSF. At this stage standard supplements containing vitamin B12 are not effective in increasing the serum and CSF levels of vitamin B12 and so constant high dose administration of vitamin B12 is required. Studies have shown that at least with dementia progression can largely be halted by such treatment. In addition studies using high dose methylcobalamin concluded that high dose methylcobalamin is a safe and effective treatment for psychiatric disorders in patients with Alzheimer-type dementia*. These workers stressed that high levels of methylcobalamin had to be reached in the CNS. Such levels are not achievable with high dose oral supplements++. A topical form of vitamin B12 has recently been developed that is a specially formulated preparation that is an easy to apply, needle-free delivery system to the skin of the Alzheimer's disease patient, and which has the potential to provide high doses of VB12 to the AD patient without the use of needles**. This pain-free form of delivery greatly increases the patient comfort experienced during the administration of the medication and allows for self-medication without the need for medical staff or any special training. It has recently become apparent that oral supplementation with vitamin B12 does not provide enough vitamin B12 to overcome vitamin B12 deficiency due to the limited uptake capacity of the intestine for vitamin B12, hence there is a requirement for higher initial doses of vitamin B12 to be supplied either by injection or via the topical vitamin B12 formulation.  In addition, the topical formulation of vitamin B12 is particularly suited to patients who may have gastro-intestinal problems, such as gastric ulcers, atrophic gastritis, Crohnís Disease and Ulcerative Colitis, or who are on Metformin medication, which can often lead to vitamin B12 deficiency.   

Further Information on Vitamin B12 and Alzheimer's Disease

* Ikea etal, 1992

++Mitsuyama etal, 1988

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Supplemental scientific references on vitamin B12 and Alzheimer's Disease

Supplemental scientific references on vitamin B12 and Dementia