title: Vitamin B status and cognitive performance in preclinical and clinical Alzheimer's disease: data from the Kungsholmen Project.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  These findings suggest that the influence of vitamin B deficiency on cognitive functioning is overshadowed by the neurodegenerative processes associated with AD.
authors.affiliation: Department of Psychology, Stockholm University, Stockholm, Sweden. akewah@psychology.su.se
authors.forename: Ake
authors.initials: A
authors.lastname: Wahlin
authors.forename: Kjell
authors.initials: K
authors.lastname: Fahlander
authors.forename: Tarja-Brita Robins
authors.initials: TB
authors.lastname: Wahlin
authors.forename: David
authors.initials: D
authors.lastname: Bunce
authors.forename: Lars
authors.initials: L
authors.lastname: Bäckman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D005494:Folic Acid Deficiency / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000175:diagnosis / Q000453:epidemiology; D011159:Population Surveillance; D021641:Recognition, Psychology; D012307:Risk Factors; D013028:Space Perception / Q000502:physiology; D014796:Visual Perception / Q000502:physiology; D014804:Vitamin B Deficiency / Q000188:drug therapy / Q000453:epidemiology*