title: Do MCI patients with vitamin B12 deficiency have distinctive cognitive deficits?
abstract: BACKGROUND
  Vitamin 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.
  
  
  RESULTS
  From 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.
  
  
  CONCLUSIONS
  MCI 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.
authors.affiliation: Dementia Clinics, Faculty of Medicine, University of Lisbon, Lisbon, Portugal. dinasilva@fm.ul.pt.
authors.forename: Dina
authors.initials: D
authors.lastname: Silva
authors.forename: Ulrike
authors.initials: U
authors.lastname: Albers
authors.forename: Isabel
authors.initials: I
authors.lastname: Santana
authors.forename: Margarida
authors.initials: M
authors.lastname: Vicente
authors.forename: Isabel Pavão
authors.initials: IP
authors.lastname: Martins
authors.forename: Ana
authors.initials: A
authors.lastname: Verdelho
authors.forename: Manuela
authors.initials: M
authors.lastname: Guerreiro
authors.forename: Alexandre
authors.initials: A
authors.lastname: de-Mendonça
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D013997:Time Factors; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000150:complications / Q000503:physiopathology*
chemical_list: D014805:Vitamin B 12