title: Vitamin B12, cognition, and brain MRI measures: a cross-sectional examination.
abstract: OBJECTIVE
  To investigate the interrelations of serum vitamin B12 markers with brain volumes, cerebral infarcts, and performance in different cognitive domains in a biracial population sample cross-sectionally.
  
  
  METHODS
  In 121 community-dwelling participants of the Chicago Health and Aging Project, serum markers of vitamin B12 status were related to summary measures of neuropsychological tests of 5 cognitive domains and brain MRI measures obtained on average 4.6 years later among 121 older adults.
  
  
  RESULTS
  Concentrations of all vitamin B12-related markers, but not serum vitamin B12 itself, were associated with global cognitive function and with total brain volume. Methylmalonate levels were associated with poorer episodic memory and perceptual speed, and cystathionine and 2-methylcitrate with poorer episodic and semantic memory. Homocysteine concentrations were associated with decreased total brain volume. The homocysteine-global cognition effect was modified and no longer statistically significant with adjustment for white matter volume or cerebral infarcts. The methylmalonate-global cognition effect was modified and no longer significant with adjustment for total brain volume.
  
  
  CONCLUSIONS
  Methylmalonate, a specific marker of B12 deficiency, may affect cognition by reducing total brain volume whereas the effect of homocysteine (nonspecific to vitamin B12 deficiency) on cognitive performance may be mediated through increased white matter hyperintensity and cerebral infarcts. Vitamin B12 status may affect the brain through multiple mechanisms.
authors.affiliation: Department of Clinical Nutrition 425 TOB, Rush University Medical Center, 1700 West Van Buren St., Chicago, IL 60612, USA. ctangney@rush.edu
authors.forename: C C
authors.initials: CC
authors.lastname: Tangney
authors.forename: N T
authors.initials: NT
authors.lastname: Aggarwal
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: R S
authors.initials: RS
authors.lastname: Wilson
authors.forename: C
authors.initials: C
authors.lastname: Decarli
authors.forename: D A
authors.initials: DA
authors.lastname: Evans
authors.forename: M C
authors.initials: MC
authors.lastname: Morris
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D020520:Brain Infarction / Q000378:metabolism / Q000473:pathology; D002641:Chicago; D003071:Cognition / Q000502:physiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005650:Fumarates / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008298:Maleates / Q000378:metabolism; D009483:Neuropsychological Tests; D012111:Residence Characteristics; D012189:Retrospective Studies; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D005650:Fumarates; D008298:Maleates; C073341:citraconic acid; D014805:Vitamin B 12