Do MCI patients with vitamin B12 deficiency have distinctive cognitive deficits?

Dina Silva,Margarida Vicente,Isabel Pavão Martins,Manuela Guerreiro,Ulrike Albers,Ana Verdelho,Alexandre De-Mendonça,Isabel Santana

doi:10.1186/1756-0500-6-357

Abstract

BackgroundVitamin B12 deficiency is common in older people, and may be responsible for reversible dementia. Low serum vitamin B12 levels were also observed in patients with Mild Cognitive Impairment (MCI). It is not known whether patients with vitamin B12 deficiency have a distinctive profile of cognitive impairment different from the episodic memory deficit usually observed in MCI.ResultsFrom a cohort of 310 patients with MCI followed in a memory clinic in Lisbon, only 10 cases with vitamin B12 deficiency were found. From collaboration with other neurologists, 5 further patients with vitamin B12 deficiency were added. These cases were compared to MCI patients with normal vitamin B12 levels in a ratio 1:3. The duration of subjective cognitive symptoms was significantly shorter in MCI patients with B12 deficiency (1.2±1.0 years) as compared to MCI patients with normal vitamin B12 levels (3.4±3.0 years, p<0.001, Student’ t test). There were no statistically significant differences in the neuropsychological tests between MCI patients with and without vitamin B12 deficiency. Vitamin B12 was started in MCI patients with vitamin B12 deficiency, with no noticeable clinical improvement.ConclusionMCI patients with low levels of vitamin B12 had no particular profile of cognitive impairment, however vitamin B12 deficiency might have precipitated the onset of symptoms. The effect of vitamin B12 supplementation in patients with MCI and low vitamin B12 levels should be clarified by future prospective studies.

Highlights

Vitamin B12 deficiency is common in older people, and may be responsible for reversible dementia
It was possible to add 5 further cases of Mild Cognitive Impairment (MCI) patients with vitamin B12 deficiency from the other participant neurologists to achieve the sample size needed for the power and significance established
The duration of cognitive symptoms was significantly shorter in MCI patients with B12 deficiency (1.2±1.0 years) as compared to MCI patients with normal vitamin B12 levels (3.4±3.0 years, p

Summary

Introduction

Vitamin B12 deficiency is common in older people, and may be responsible for reversible dementia. In a review of 32 studies, vitamin B12 deficiency was responsible for about 1% of the reversible dementias [5]. In another study performed in non-demented elderly subjects, low concentrations of vitamin B12 were associated with poorer performance in a spatial copying test [11]. In a sample of non-demented subjects older than 75, low levels of vitamin B12 were associated with decreased performance in a modified block design test, which evaluates abstraction and visuospatial abilities [12]. Different cognitive domains were reported to be affected in nondemented elderly subjects with vitamin B12 deficiency

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