title: Vitamin B12 and homocysteine levels and 6-year change in peripheral nerve function and neurological signs.
abstract: BACKGROUND
  Low vitamin B12 and high homocysteine (Hcy) levels are common in older adults and may be associated with worse neurological function. The aim of this study is to determine whether changes in B12 or Hcy levels are associated with longitudinal changes in peripheral nerve function and clinical neurological signs and symptoms.
  
  
  METHODS
  Participants aged 60 years and older at baseline (n = 678; 72.2 ± 6.2 years; 43.5% male) were from the InCHIANTI Study. Low B12 (<260 pmol/L) and high Hcy (≥13 μmol/L) were measured at baseline and 3-year follow-up. Neurological function was assessed by peroneal nerve conduction amplitude (compound motor action potential) and velocity, neurological examination, and peripheral neuropathy symptoms at baseline, 3-year, and 6-year follow-up.
  
  
  RESULTS
  At baseline, 43.8% had low B12 levels and 58.6% had high Hcy levels. Over 6 years, 12.4% declined to poor compound motor action potential (<1 mV) and 42.1% declined to poor nerve conduction velocity (<40 m/s). In mixed models analyses, sustained high Hcy was associated with worse compound motor action potential compared with sustained normal Hcy (p = .04), adjusting for demographics, diabetes, and folate level. Participants whose Hcy level became high at follow-up were more likely to become unable to detect monofilament at 6-year follow-up compared with those with sustained normal Hcy (odds ratio: 5.4; 95% CI: 1.5-19.0), adjusting for demographics, diabetes, body mass index, and peripheral arterial disease. There was no association with vitamin B12 level or with symptoms.
  
  
  CONCLUSIONS
  High Hcy may be associated with worse sensory and motor peripheral nerve function. Because poor nerve function has been associated with lower strength and physical performance, these results have important implications for disability in older adults.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Kira
authors.initials: K
authors.lastname: Leishear
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Robert M
authors.initials: RM
authors.lastname: Boudreau
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Studenski
authors.forename: Caterina
authors.initials: C
authors.lastname: Rosano
authors.forename: Rosanna
authors.initials: R
authors.lastname: Abbate
authors.forename: Anna M
authors.initials: AM
authors.lastname: Gori
authors.forename: Anna M
authors.initials: AM
authors.lastname: Corsi
authors.forename: Angelo
authors.initials: A
authors.lastname: Di Iorio
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Elsa S
authors.initials: ES
authors.lastname: Strotmeyer
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D005260:Female; D005500:Follow-Up Studies; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D009460:Neurologic Examination; D010523:Peripheral Nervous System Diseases / Q000097:blood* / Q000503:physiopathology*; D010543:Peroneal Nerve / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D014805:Vitamin B 12