Vitamin B status and cognitive performance in preclinical and clinical Alzheimer's disease: data from the Kungsholmen Project.

BACKGROUND/AIMS: The impact of vitamin B status on cognitive functioning in Alzheimer's disease (AD) is disputed. Using a population-based sample, we examined the associations of vitamin B(12) and folate with cognitive functioning in clinical (n = 44) and preclinical (n = 39) AD.

METHODS

The groups were subdivided in terms of low (<200 pmol/l) versus normal levels of B(12) and low (<13 nmol/l) versus normal folate levels. Participants were administered tests of verbal and nonverbal episodic memory, visuospatial abilities and verbal fluency.

RESULTS

As expected, the preclinical AD group performed better than the AD group across most cognitive tests. More interestingly, the effects of low vitamin B(12) and folate levels were negligible across all cognitive tests in clinical and preclinical AD.

CONCLUSION

These findings suggest that the influence of vitamin B deficiency on cognitive functioning is overshadowed by the neurodegenerative processes associated with AD.