Browsing by Subject "Generalized estimating equations"

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    ADDENDUM: Critical windows of fluoride neurotoxicity in Canadian Children
    (Elsevier, 2022) Farmus, Linda; Till, Christine; Green, Rivka; Hornung, Richard; Martinez Mier, E. Angeles; Ayotte, Pierre; Muckle, Gina; Lanphear, Bruce P.; Flora, David B.; Dental Public Health and Dental Informatics, School of Dentistry
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    Critical windows of fluoride neurotoxicity in Canadian children
    (Elsevier, 2021) Farmus, Linda; Till, Christine; Green, Rivka; Hornung, Richard; Martinez Mier, E. Angeles; Ayotte, Pierre; Muckle, Gina; Lanphear, Bruce P.; Flora, David B.; Dental Public Health and Dental Informatics, School of Dentistry
    Background: Fluoride has been associated with IQ deficits during early brain development, but the period in which children are most sensitive is unknown. Objective: We assessed effects of fluoride on IQ scores across prenatal and postnatal exposure windows. Methods: We used repeated exposures from 596 mother-child pairs in the Maternal-Infant Research on Environmental Chemicals pregnancy and birth cohort. Fluoride was measured in urine (mg/L) collected from women during pregnancy and in their children between 1.9 and 4.4 years; urinary fluoride was adjusted for specific gravity. We estimated infant fluoride exposure (mg/day) using water fluoride concentration and duration of formula-feeding over the first year of life. Intelligence was assessed at 3-4 years using the Wechsler Preschool and Primary Scale of Intelligence-III. We used generalized estimating equations to examine the associations between fluoride exposures and IQ, adjusting for covariates. We report results based on standardized exposures given their varying units of measurement. Results: The association between fluoride and performance IQ (PIQ) significantly differed across prenatal, infancy, and childhood exposure windows collapsing across child sex (p = .001). The strongest association between fluoride and PIQ was during the prenatal window, B = -2.36, 95% CI: -3.63, -1.08; the association was also significant during infancy, B = -2.11, 95% CI: -3.45, -0.76, but weaker in childhood, B = -1.51, 95% CI: -2.90, -0.12. Within sex, the association between fluoride and PIQ significantly differed across the three exposure windows (boys: p = .01; girls: p = .01); among boys, the strongest association was during the prenatal window, B = -3.01, 95% CI: -4.60, -1.42, whereas among girls, the strongest association was during infancy, B = -2.71, 95% CI: -4.59, -0.83. Full-scale IQ estimates were weaker than PIQ estimates for every window. Fluoride was not significantly associated with Verbal IQ across any exposure window. Conclusion: Associations between fluoride exposure and PIQ differed based on timing of exposure. The prenatal window may be critical for boys, whereas infancy may be a critical window for girls.
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    Magnesium intake was inversely associated with hostility among American young adults
    (Elsevier, 2021) Lyu, Chen; Tsinovoi, Cari L.; Xun, Pengcheng; Song, Yiqing; Pu, Yongjia; Rosanoff, Andrea; Iribarren, Carlos; Schreiner, Pamela J.; Shikany, James M.; Jacobs, David R.; Kahe, Ka; Epidemiology, Richard M. Fairbanks School of Public Health
    Hostility is a complex personality trait associated with many cardiovascular risk factor phenotypes. Although magnesium intake has been related to mood and cardio-metabolic disease, its relation with hostility remains unclear. We hypothesize that high total magnesium intake is associated with lower levels of hostility because of its putative antidepressant mechanisms. To test the hypothesis, we prospectively analyzed data in 4,716 young adults aged 18-30 years at baseline (1985-1986) from four U.S. cities over five years of follow-up using data from the Coronary Artery Risk Development in Young Adults (CARDIA) study. Magnesium intake was estimated from a dietary history questionnaire plus supplements at baseline. Levels of hostility were assessed using the Cook-Medley scale at baseline and year 5 (1990-1991). Generalized estimating equations were applied to estimate the association of magnesium intake with hostility as repeated measures at the two time-points (baseline and year 5). General linear model was used to determine the association between magnesium intake and change in hostility over 5 years. After adjustment for socio-demographic and major lifestyle factors, a significant inverse association was observed between magnesium intake and hostility level over 5 years of follow-up. Beta coefficients (95% CI) across higher quintiles of magnesium intake were 0 (reference), -1.28 (-1.92, -0.65), -1.45 (-2.09, -0.81), -1.41 (-2.08, -0.75) and -2.16 (-2.85, -1.47), respectively (Plinear-trend<.01). The inverse association was independent of socio-demographic and major lifestyle factors, supplement use, and depression status at year 5. This prospective study provides evidence that in young adults, high magnesium intake was inversely associated with hostility level independent of socio-demographic and major lifestyle factors.