RESUMO
BACKGROUND: Folate status has been positively associated with cognitive function in many studies; however, some studies have observed associations of poor cognitive outcomes with high folate. In search of an explanation, we hypothesized that the association of folate with cognition would be modified by the interaction of high-folate status with a common 19-bp deletion polymorphism in the dihydrofolate reductase (DHFR) gene. To our knowledge, the cognitive effects of this gene have not been studied previously. OBJECTIVE: We examined the association between cognitive outcomes with the 19-bp deletion DHFR polymorphism, folate status, and their interaction with high or normal plasma folate. DESIGN: This was a pooled cross-sectional study of the following 2 Boston-based cohorts of community living adults: the Boston Puerto Rican Health Study and the Nutrition, Aging, and Memory in Elders study. Individuals were genotyped for the DHFR 19-bp deletion genotype, and plasma folate status was determined. Cognitive outcomes included the Mini-Mental State Examination, Center for Epidemiologic Studies Depression Scale, and factor scores for the domains of memory, executive function, and attention from a set of cognitive tests. RESULTS: The prevalence of the homozygous deletion (del/del) genotype was 23%. In a multivariable analysis, high folate status (>17.8 ng/mL) was associated with better memory scores than was normal-folate status (fourth-fifth quintiles compared with first-third quintiles: ß ± SE = -0.22 ± 0.06, P < 0.01). Carriers of the DHFR del/del genotype had worse memory scores (ß ± SE = -0.24 ± 0.10, P < 0.05) and worse executive scores (ß = -0.19, P < 0.05) than did those with the del/ins and ins/ins genotypes. Finally, we observed an interaction such that carriers of the del/del genotype with high folate had significantly worse memory scores than those of both noncarriers with high-folate and del/del carriers with normal-folate (ß-interaction = 0.26 ± 0.13, P < 0.05). CONCLUSIONS: This study identifies a putative gene-nutrient interaction that, if confirmed, would predict that a sizable minority carrying the del/del genotype might not benefit from high-folate status and could see a worsening of memory. An understanding of how genetic variation affects responses to high-folate exposure will help weigh risks and benefits of folate supplementation for individuals and public health.
Assuntos
Deficiência de Ácido Fólico/genética , Deleção de Genes , Transtornos da Memória/etiologia , Estado Nutricional , Polimorfismo Genético , Tetra-Hidrofolato Desidrogenase/genética , Negro ou Afro-Americano , Idoso , Idoso de 80 Anos ou mais , Boston/epidemiologia , Estudos de Coortes , Estudos Transversais , Feminino , Ácido Fólico/intoxicação , Deficiência de Ácido Fólico/enzimologia , Deficiência de Ácido Fólico/fisiopatologia , Estudos de Associação Genética , Hispânico ou Latino , Humanos , Masculino , Transtornos da Memória/epidemiologia , Pessoa de Meia-Idade , Nutrigenômica/métodos , Prevalência , Porto Rico/etnologia , Tetra-Hidrofolato Desidrogenase/metabolismo , População BrancaRESUMO
BACKGROUND: The S-adenosylmethionine synthetase type 1 (MAT1A) gene encodes a key enzyme in one-carbon nutrient metabolism. OBJECTIVE: This study aimed to determine the association of MAT1A variants with homocysteine, DNA damage, and cardiovascular disease (CVD). DESIGN: Eight variants of MAT1A were examined for associations with hypertension, stroke, CVD, homocysteine, and DNA damage in 1006 participants of the Boston Puerto Rican Health Study. Two variants were replicated in 1147 participants of the Nutrition, Aging, and Memory in Elders Study. RESULTS: Two variants and haplotypes were strongly associated with hypertension and stroke, independent of methylenetetrahydrofolate reductase (MTHFR) variants. Homozygotes of the MAT1A d18777A (rs3851059) allele had a significantly greater likelihood of stroke (odds ratio: 4.30; 95% CI: 1.34, 12.19; P = 0.006), whereas 3U1510A (rs7087728) homozygotes had a lower likelihood of hypertension (odds ratio: 0.67; 95% CI: 0.48, 0.95; P = 0.022) and stroke (odds ratio: 0.35; 95% CI: 0.15, 0.82; P = 0.015). A similar trend of association was observed in a second elderly population. Furthermore, strong interactions between MAT1A genotypes and vitamin B-6 status were found. Carriers of the nonrisk allele 3U1510A had a lower 8-hydroxydeoxyguanosine concentration--a biomarker of oxidative DNA damage--when plasma vitamin B-6 was high, whereas homozygotes for the risk-allele 3U1510G had higher 8-hydroxydeoxyguanosine concentrations, regardless of vitamin B-6 status. CONCLUSIONS: MAT1A variants were strongly associated with hypertension and stroke. Improving folate and vitamin B-6 status might decrease the CVD risk of only a subset of the population, depending on genotype. These findings suggest that impairments in methylation activity, independent of homocysteine, have an effect on CVD risk.
Assuntos
Dano ao DNA , Ácido Fólico/sangue , Variação Genética , Hipertensão/genética , Metionina Adenosiltransferase/genética , Acidente Vascular Cerebral/genética , Vitamina B 6/sangue , Adulto , Idoso , Boston , Doenças Cardiovasculares/genética , Transtornos Cognitivos/genética , Feminino , Genótipo , Homocisteína/sangue , Humanos , Hipertensão/prevenção & controle , Estilo de Vida , Masculino , Memória , Pessoa de Meia-Idade , Porto Rico/etnologia , Acidente Vascular Cerebral/prevenção & controleRESUMO
OBJECTIVES: To compare endothelium-dependent vasomotor response in healthy younger and older subjects without classic cardiovascular risk factors, with high and normal fasting homocysteine (tHcy) levels. DESIGN: We compared endothelium-dependent vasodilatation, using ultrasound, in healthy younger (aged 18-40) and older (> or =70) people with normal (<13 micromol/L) and high (>15 micromol/L) tHcy levels. Exclusion criteria were smoking, personal history of cardiovascular disease, hypertension, chronic diseases, vitamin intake, obesity, abnormal serum lipids levels, and creatinine higher than 130 micromol/L. SETTING: Research laboratory. MEASUREMENTS: In addition to tHcy levels, serum folate and vitamin B12 levels were measured. RESULTS: We studied 17 younger and 12 older hyperhomocysteinemic subjects and respective aged-matched normohocysteinemic subjects. Endothelium-dependent vasodilatation was lower in the hyperhomocysteinemic older people (P <.01) than in all younger subjects and in normohomocysteinemic older people. Serum vitamin B12 levels were higher in younger and older normal controls. Folic acid levels were higher in younger controls and in both older groups. CONCLUSIONS: This study shows an effect of high circulating tHcy on vascular reactivity in older people. Because serum levels of tHcy are associated with nutritional status of vitamin B12 and folic acid, prospective studies are necessary to demonstrate the effects of a long-term nutritional supplementation with vitamins on vascular function and global cardiovascular risk.