November 28, 2012

Vitamin B12 Deficiency And Alzheimer's Disease: Early Studies

Cerebrospinal fluid B12 and Alzheimer’s disease:

Cees Van Tiggelen first suggested in 1983 that vitamin B12 deficiency occurs in association with Alzheimers Disease (AD) (J.Orthomolec.Psych:13;97-104). He showed that AD patients have very low levels of vitamin B12 in cerebrospinal fluid (CSF).  Ikeda et al and Nijst et al later confirmed this fascinating discovery (Acta Psych Scand; 1990:82:327-9. J Neurol.Neurosurg.Psych;1990:53:951-4).

Blood B12 and Alzheimer's disease:

Meanwhile, Cole and Prchal measured blood vitamin B12 levels in 20 elderly patients with AD and 20 age-matched healthy individuals (Age.Ageing 1984:13:101-5).  They found that blood vitamin B12 levels were significantly lower in the AD patients. This was confirmed by others (Arch.Intern.Med:147:429-31).  Interestingly, the typical blood findings associated with deficiency (macrocytic anaemia) were often absent.

Active and "inactive" B12:

Later, working in Sweden, Regland et al also found lower blood vitamin B12 levels in 56 patients with AD compared to 54 patients with vascular dementia (Acta Psych Scand 1988:78:451-7).  With regard to B12 levels in CSF, Regland also showed that low CSF B12 levels might be explained by inactive B12 analogues somehow interfering with the transport of the vitamin; he found a lower ratio of active B12/ inactive B12 "analogues" in patients with dementia (Dementia.1990:1:272-7).

So, is there an association between Vitamin B12 and Alzheimer's Disease?

Although there seems good evidence for an association between B12 deficiency and AD, it was argued that because both conditions occur commonly in the elderly it is not perhaps not surprising that many subjects have a combination of the two (Am.J.Clin.Nutr. 1997:66:741-9).

Another potential criticism of these early studies was that " could we be sure these patients had AD, and not another type of dementia?"  However, in later updates we will look at further strong evidence for vitamin B12 deficiency in patients with genetically and pathologically confirmed AD.

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