title: Serum homocysteine and folate concentrations are associated with prevalent age-related hearing loss.
abstract: Elevated total serum homocysteine (tHcy) concentrations associated with vitamin B-12 or folate deficiencies may adversely affect blood flow to the cochlea, leading to age-related hearing loss (presbycusis). However, only 2 small cross-sectional studies have assessed the link between folate, vitamin B-12, or tHcy and presbycusis. We aimed to determine both the cross-sectional and longitudinal association between serum concentrations of folate, vitamin B-12, or tHcy and risk of age-related hearing loss. The Blue Mountains Hearing Study is a population-based survey of age-related hearing loss (1997-1999 to 2002-2004). Presbycusis was measured in 2956 participants (aged >or=50 y) and was defined as the pure-tone average of frequencies 0.5, 1.0, 2.0, and 4.0 kHz >25 dB hearing level (HL). Serum concentrations of folate, vitamin B-12, and tHcy were determined from blood samples. Participants with elevated tHcy (>20 micromol/L) concentrations had a 64% increased likelihood of prevalent hearing loss (>25 dB HL) [multivariate-adjusted odds ratio (OR) 1.64; 95% CI, 1.06-2.53]. Low serum folate levels (<11 nmol/L) increased the odds of prevalent mild hearing loss (>25-40 dB HL), multivariate-adjusted [OR 1.37 (CI 1.04-1.81)]. Serum vitamin B-12, however, was not significantly associated with prevalent hearing loss. Serum folate, vitamin B-12, and tHcy concentrations were also not significantly associated with an increased risk of incident hearing loss. Serum concentrations of tHcy and folate were associated with age-related hearing loss cross-sectionally, but no temporal links were observed, which could be due to insufficient study power. Further, large prospective studies will be required in the future to assess these associations.
authors.affiliation: Centre for Vision Research, Department of Ophthalmology, Westmead Millennium Institute, University of Sydney, Sydney, NSW, Australia.
authors.forename: Bamini
authors.initials: B
authors.lastname: Gopinath
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Flood
authors.forename: Elena
authors.initials: E
authors.lastname: Rochtchina
authors.forename: Catherine M
authors.initials: CM
authors.lastname: McMahon
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D003430:Cross-Sectional Studies; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006306:Health Surveys; D034381:Hearing Loss / Q000097:blood* / Q000453:epidemiology; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12