Browsing by Author "Fly, Alyce D."

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    Association of magnesium intake with sleep duration and sleep quality: findings from the CARDIA study
    (Oxford University Press, 2022) Zhang, Yijia; Chen, Cheng; Lu, Liping; Knutson, Kristen L.; Carnethon, Mercedes R.; Fly, Alyce D.; Luo, Juhua; Haas, David M.; Shikany, James M.; Kahe, Ka; Obstetrics and Gynecology, School of Medicine
    Study objectives: As an antagonist of calcium (Ca), magnesium (Mg) has been implicated in the regulation of sleep. We aimed to examine the longitudinal associations of Mg intake and Ca-to-Mg intake ratio (Ca:Mg) with sleep quality and duration. Methods: The study sample consisted of 3,964 participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary and supplementary intake of Mg were obtained using the CARDIA Dietary History at baseline (1985-1986), exam years 7 and 20. Self-reported sleep outcomes were measured at years 15 and 20. Sleep quality was rating from 1 (very good) to 5 (very bad). We categorized sleep duration to <7, 7-9, and >9 h. Generalized estimating equation was used to examine the associations of interest as repeated measures at the two time points. Results: After adjustment for potential confounders, Mg intake was borderline associated with better sleep quality [highest quartile (Q4) vs. intake quartile (Q1): odds ratio (OR) = 1.23; 95% CI = 0.999, 1.50, ptrend = 0.051]. Participants in Q4 were also less likely to have short sleep (<7 h) compared to those in Q1 (OR = 0.64; 95% CI = 0.51, 0.81, ptrend = 0.012). The observed association with short sleep persisted among participants without depressive disorders (Q4 vs. Q1: OR = 0.64; 95% CI = 0.49, 0.82, ptrend < 0.001), but not among individuals with depressive disorder. Ca:Mg was not associated with either outcomes, regardless of depression status. Conclusions: Mg intake was associated with both sleep outcomes in this longitudinal analysis. Randomized controlled trials with objective measures of sleep are warranted to establish the potential causal inference.
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    Association of Urinary Cadmium Concentration With Cognitive Impairment in US Adults: A Longitudinal Cohort Study
    (Wolters Kluwer, 2024) Lu, Liping; Zhang, Yijia; Angley, Meghan; Bejerano, Shai; Brockman, John D.; McClure, Leslie A.; Unverzagt, Frederick W.; Fly, Alyce D.; Kahe, Ka; Psychiatry, School of Medicine
    Background and objectives: Studies have indicated that cadmium (Cd) exposure is associated with neurotoxicity. However, data linking Cd exposure to cognitive impairment are sparse. We aimed to investigate the association between urinary Cd concentration and cognitive impairment in US adults. Methods: The REasons for Geographic and Racial Differences in Stroke (REGARDS) study is an ongoing population-based prospective cohort study that enrolled 30,239 Black and White US adults aged 45 years or older at baseline (2003-2007). In a randomly selected subcohort of REGARDS participants who were free of cognitive impairment or stroke at baseline, certain trace element concentrations, including urinary creatinine-corrected Cd, were measured using biospecimens collected and stored at baseline. During an average of 10 years of follow-up, global cognitive impairment was assessed annually using the Six-Item Screener, and domain-based cognitive impairment, including verbal learning, memory, and executive function, was evaluated every other year using the Enhanced Cognitive Battery. Multivariable-adjusted logistic regression models were used to examine the association between urinary Cd concentration and the odds of global or domain-based cognitive impairment. Results: A total of 2,172 participants (mean age: 64.1 ± 9.0 years; female: 54.8%; Black participants: 38.7%) with available data on urinary Cd concentration, including 195 cases of global cognitive impairment and 53 cases of domain-based cognitive impairment, were included in the analyses. While there was no association between Cd and cognitive impairment in the full sample, there was a significant positive association of urinary Cd concentration with global cognitive impairment among White but not Black participants. The odds of cognitive impairment for White participants in the high urinary Cd concentration group (≥median) were doubled compared with those in the low urinary Cd group (odds ratio 2.07, 95% CI 1.18-3.64). Sex, age, region, smoking pack-years, alcohol consumption, and other related metals did not materially modify the associations of interest. Discussion: Findings from this prospective cohort study suggest that urinary Cd concentrations are associated with global cognitive impairment among White but not Black individuals. Further studies with repeatedly measured Cd exposure, larger sample sizes, and longer duration are needed to confirm our findings and explore the potential explanations for the observed racial discrepancy, such as the impact of smoking.
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    Normalization of flow-mediated dilation to shear stress area under the curve eliminates the impact of variable hyperemic stimulus
    (BioMed Central, 2008-09-04) Padilla, Jaume; Johnson, Blair D.; Newcomer, Sean C.; Wilhite, Daniel P.; Mickleborough, Timothy D.; Fly, Alyce D.; Mather, Kieren J.; Wallace, Janet P.; Medicine, School of Medicine
    Background Normalization of brachial artery flow-mediated dilation (FMD) to individual shear stress area under the curve (peak FMD:SSAUC ratio) has recently been proposed as an approach to control for the large inter-subject variability in reactive hyperemia-induced shear stress; however, the adoption of this approach among researchers has been slow. The present study was designed to further examine the efficacy of FMD normalization to shear stress in reducing measurement variability. Methods Five different magnitudes of reactive hyperemia-induced shear stress were applied to 20 healthy, physically active young adults (25.3 ± 0. 6 yrs; 10 men, 10 women) by manipulating forearm cuff occlusion duration: 1, 2, 3, 4, and 5 min, in a randomized order. A venous blood draw was performed for determination of baseline whole blood viscosity and hematocrit. The magnitude of occlusion-induced forearm ischemia was quantified by dual-wavelength near-infrared spectrometry (NIRS). Brachial artery diameters and velocities were obtained via high-resolution ultrasound. The SSAUC was individually calculated for the duration of time-to-peak dilation. Results One-way repeated measures ANOVA demonstrated distinct magnitudes of occlusion-induced ischemia (volume and peak), hyperemic shear stress, and peak FMD responses (all p < 0.0001) across forearm occlusion durations. Differences in peak FMD were abolished when normalizing FMD to SSAUC (p = 0.785). Conclusion Our data confirm that normalization of FMD to SSAUC eliminates the influences of variable shear stress and solidifies the utility of FMD:SSAUC ratio as an index of endothelial function.