title: Community-living nonagenarians in northern ireland have lower plasma homocysteine but similar methylenetetrahydrofolate reductase thermolabile genotype prevalence compared to 70-89-year-old subjects.
abstract: This cross-sectional study assessed relationships between plasma homocysteine, 'thermolabile' methylenetetrahydrofolatereductase (MTHFR) genotype, B vitamin status and measures of renal function in elderly (70-89 years) and nonagenarian (90+ years) subjects, with the hypothesis that octo/nonagenarian subjects who remain healthy into old age as defined by 'Senieur' status might show reduced genetic or environmental risk factors usually associated with hyperhomocysteinaemia. Plasma homocysteine was 9.1 micromol/l (geometric mean [GM]) for all elderly subjects. Intriguingly, homocysteine was significantly lower in 90+ (GM; 8.2 micromol/l) compared to 70-89-year-old subjects (GM; 9.8 micromol/l) despite significantly lower glomerular filtration rate (GFR) and serum B12 in nonagenarian subjects and comparable MTHFR thermolabile (TT) genotype frequency, folate and B6 status to 70-89-year-olds. For all elderly subjects, the odds ratio and 95% confidence intervals for plasma homocysteine being in the highest versus lowest quartile was 4.27 (2.04-8.92) for age <90 compared >90 years, 3.4 (1.5-7.8) for serum folate <10.7 compared >10.7nmol/l, 3.0 (0.9-10.2) for creatinine >140 compared <140 umol/l and 2.1 (1.0-4.4) for male sex. This study shows that plasma homocysteine does not invariably increase with age. Compared to similarly enlisted 70-89-year-olds, apparently well, mentally alert, community-living 90+ year olds approximating 'Senieur' status, show lower homocysteine, which is unexplained by renal function, TT genotype and B vitamin status, suggesting that lower homocysteine may be associated with survival.
authors.affiliation: Cardiovascular Research Centre, The Queen's University of Belfast, Belfast, UK. i.rea@qub.ac.uk
authors.forename: I M
authors.initials: IM
authors.lastname: Rea
authors.forename: D
authors.initials: D
authors.lastname: McMaster
authors.forename: J V
authors.initials: JV
authors.lastname: Woodside
authors.forename: I S
authors.initials: IS
authors.lastname: Young
authors.forename: G P
authors.initials: GP
authors.lastname: Archbold
authors.forename: T
authors.initials: T
authors.lastname: Linton
authors.forename: S
authors.initials: S
authors.lastname: Lennox
authors.forename: H
authors.initials: H
authors.lastname: McNulty
authors.forename: D L
authors.initials: DL
authors.lastname: Harmon
authors.forename: A S
authors.initials: AS
authors.lastname: Whitehead
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002853:Chromatography, Liquid; D003430:Cross-Sectional Studies; D005260:Female; D015870:Gene Expression; D005838:Genotype; D005919:Glomerular Filtration Rate; D006304:Health Status; D006710:Homocysteine / Q000097:blood* / Q000378:metabolism; D006801:Humans; D020138:Hyperhomocysteinemia / Q000175:diagnosis / Q000453:epidemiology; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D015999:Multivariate Analysis; D009660:Northern Ireland / Q000453:epidemiology; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000097:blood* / Q000235:genetics*; D011159:Population Surveillance; D015995:Prevalence; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D006710:Homocysteine; D014803:Vitamin B Complex; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)