November 12, 2012

Vitamin B12 Deficiency And Cognition: Early Studies, Part 2

Early Intervention Studies:

In this Blog Update we will look at a few intervention studies on the effects of Vitamin B12 on cognition. These were all performed in the closing decade of the last century.

A "Time Limited Window of Opportunity?":

Martin et al investigated the effects of Vitamin B12 on cognition in a group of 18 elderly individuals with low serum B12 and cognitive dysfunction (JAGS. 1992;40:168-72).  A Dementia Rating Scale score improved for 11 participants.  However, only those whose impairment on mental-status testing had been in the mild range and who had been symptomatic for less than a year improved.  Most notably, those who had been symptomatic for less than 6 months responded best.

Electrophysiological Evidence:

Carmel and colleagues evaluated B12, neuropsychologic and electrophysiologic indices in 13 older adults with dementia and with low blood vitamin B12 levels before and after B12 supplementation (Eur.J.Haematol 1995;54:245-53).  Improvements were found for homocysteine and haemoglobin levels, neuropathological symptoms, EEG abnormalities, and visual evoked and somatosensory abnormalities.

Effects in "mild cognitive impairment" versus "dementia":

Eastley et al identified 125 patients out of 1,432 attending a memory disorders clinic who had low serum B12 (Int.J.Ger.Psych. 2000; 15:226-33).  They assessed 66 of these with dementia and 22 with cognitive impairment before and after B12 supplementation.  There was no change in the dementia group, but patients in the cognitively impaired group improved on measures of verbal fluency.


In summary, these early studies suggest that there is some benefit of Vitamin B12 supplementation on cognition, at least in those patients with mild cognitive impairment.

In later Blog Updates we will look at more recent trials which used a combination of B vitamins and a much longer period of observation and follow up.




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