Urinary Fluoride Levels among Canadians with and without Community Water Fluoridation

Drinking water is a major source of dietary fluoride intake in communities with water fluoridation. We examined the association between urinary fluoride adjusted for specific gravity (UFSG) and tap water fluoride levels, by age and sex, among individuals living in Canada. Participants included 1629 individuals aged 3 to 79 years from Cycle 3 (2012-2013) of the Canadian Health Measures Survey. We used multiple linear regression to estimate unique associations of tap water fluoride levels, age, sex, ethnicity, body mass index (BMI), use of fluoride-containing dental products, smoking in the home, and tea consumption with UFSG. UFSG concentration was significantly higher among participants who received fluoridated drinking water (mean = 1.06 mg/L, standard deviation = 0.83) than among those who did not (M = 0.58 mg/L, SD = 0.47), p < 0.01. UFSG increased over adulthood (ages 19 to 79). Higher UFSG concentration was associated with being female, tea drinking, and smoking in the home. In conclusion, community water fluoridation is a major source of contemporary fluoride exposure for Canadians. Lifestyle factors including tea consumption, as well as demographic variables such as age and sex, also predict urinary fluoride level, and are therefore important factors when interpreting population-based fluoride biomonitoring data.

Fluoride exposure and duration and quality of sleep in a Canadian population-based sample

BACKGROUND

Fluoride from dietary and environmental sources may concentrate in calcium-containing regions of the body such as the pineal gland. The pineal gland synthesizes melatonin, a hormone that regulates the sleep-wake cycle. We examined associations between fluoride exposure and sleep outcomes among older adolescents and adults in Canada.

METHODS

We used population-based data from Cycle 3 (2012-2013) of the Canadian Health Measures Survey. Participants were aged 16 to 79 years and 32% lived in communities supplied with fluoridated municipal water. Urinary fluoride concentrations were measured in spot samples and adjusted for specific gravity (UF_SG; n = 1303) and water fluoride concentrations were measured in tap water samples among those who reported drinking tap water (n = 1016). We used multinomial and ordered logistic regression analyses (using both unweighted and survey-weighted data) to examine associations of fluoride exposure with self-reported sleep outcomes, including sleep duration, frequency of sleep problems, and daytime sleepiness. Covariates included age, sex, ethnicity, body mass index, chronic health conditions, and household income.

RESULTS

Median (IQR) UF_SG concentration was 0.67 (0.63) mg/L. Median (IQR) water fluoride concentration was 0.58 (0.27) mg/L among participants living in communities supplied with fluoridated municipal water and 0.01 (0.06) mg/L among those living in non-fluoridated communities. A 0.5 mg/L higher water fluoride level was associated with 34% higher relative risk of reporting sleeping less than the recommended duration for age [unweighted: RRR = 1.34, 95% CI: 1.03, 1.73; p = .026]; the relative risk was higher, though less precise, using survey-weighted data [RRR = 1.96, 95% CI: 0.99, 3.87; p = .05]. UF_SG was not significantly associated with sleep duration. Water fluoride and UF_SG concentration were not significantly associated with frequency of sleep problems or daytime sleepiness.

CONCLUSIONS

Fluoride exposure may contribute to sleeping less than the recommended duration among older adolescents and adults in Canada.

Sex-specific neurotoxic effects of early-life exposure to fluoride: A review of the epidemiologic and animal literature

PURPOSE OF REVIEW

A growing body of evidence suggests adverse neurodevelopmental effects of early-life exposure to fluoride that may differ depending on timing of exposure and sex of the exposed. We conducted a literature search to identify the animal and human epidemiologic studies that examined sex-specific neurodevelopmental differences in response to prenatal and postnatal exposure to fluoride.

RECENT FINDINGS

Six of 138 animal studies and 15 of 106 human epidemiologic studies tested for sex-specific effects. Prenatal exposure to fluoride was associated with a male susceptibility to adverse behavioural effects in four of six animal studies and lower IQ in one of three prospective cohort studies. The body of evidence examining sex-effects associated with postnatal fluoride exposure was scarce, and many animal and cross-sectional human studies were considered to have a high risk of bias.

SUMMARY

Compared to females, male offspring appear to be more sensitive to prenatal, but not postnatal, exposure to fluoride. We discuss several sex-specific mechanisms and emphasize the need for future research.

Associations between Urinary, Dietary, and Water Fluoride Concentrations among Children in Mexico and Canada

Fluoride, which may be toxic to the developing brain, is added to salt in Mexico and drinking water in Canada to prevent dental caries. We compared childhood urinary fluoride (CUF) concentrations in Mexico City and Canada to characterize patterns of fluoride exposure in these two populations. We also examined associations of CUF with dietary and water fluoride levels in Mexico City and Canada respectively. We included 561 children (ages 4–6; mean age 4.8 years) from the Programming Research in Obesity, Growth, Environment, and Social Stress (PROGRESS) cohort in Mexico City, and 645 children (ages 2–6; mean age 3.7 years) from the Maternal–Infant Research on Environmental Chemicals (MIREC) cohort in Canada. We applied Spearman correlations, T-tests, ANOVA or covariate-adjusted linear regression to examine associations of CUF (mg/L; adjusted for specific gravity) with demographics and dietary or water fluoride concentrations. We used Welch equivalence testing to compare means across cohorts. Mean (SD) CUF was equivalent (t = 4.26, p < 0.001) in PROGRESS: 0.74 (0.42) and fluoridated Canadian communities: 0.66 (0.47), but lower in non-fluoridated Canadian communities: 0.42 (0.31) (t = −6.37, p < 0.001). Water fluoride concentrations were significantly associated with CUF after covariate adjustment for age and sex in MIREC (B = 0.44, 95% CI: 0.30, 0.59, p < 0.001). In contrast, daily food and beverage fluoride intake was not associated with CUF in PROGRESS (p = 0.82). We found that CUF levels are comparable among children in Mexico City and fluoridated Canadian communities, despite distinct sources of exposure. Community water fluoridation is a major source of fluoride exposure for Canadian children.

A Benchmark Dose Analysis for Maternal Pregnancy Urine-Fluoride and IQ in Children

As a safe exposure level for fluoride in pregnancy has not been established, we used data from two prospective studies for benchmark dose modeling. We included mother-child pairs from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort in Mexico and the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort in Canada. Children were assessed for IQ at age 4 (n=211) and between 6 and 12 years (n=287) in the ELEMENT cohort and between ages 3 and 4 years (n=512) in the MIREC cohort. We calculated covariate-adjusted regression coefficients and their standard errors to explore the concentration-effect function for maternal urinary fluoride with children's IQ, including possible sex-dependence. Assuming a benchmark response of 1 IQ point, we derived benchmark concentrations (BMCs) of maternal urinary fluoride and benchmark concentration levels (BMCLs). No deviation from linearity was detected from the results of the two studies. Using a linear slope, the BMC for maternal urinary fluoride associated with a 1-point decrease in IQ scores of preschool-aged boys and girls was 0.29 mg/L (BMCL, 0.18 mg/L). The BMC was 0.30 mg/L (BMCL, 0.19 mg/L) when pooling the IQ scores from the older ELEMENT children and the MIREC cohort. Boys showed slightly lower BMC values compared with girls. Relying on two prospective studies, maternal urine-fluoride exposure at levels commonly occurring in the general population, the joint data showed BMCL results about 0.2 mg/L. These results can be used to guide decisions on preventing excess fluoride exposure in vulnerable populations.

Consistent Physical Activity and Future Neurocognitive Problems in Adult Survivors of Childhood Cancers: A Report From the Childhood Cancer Survivor Study

PURPOSE

To investigate longitudinal associations between physical activity (PA) and neurocognitive problems in adult survivors of childhood cancer.

METHODS

A total of 12,123 5-year survivors diagnosed between 1970 and 1999 (median [range] age at diagnosis, 7 [0-21] years, time since diagnosis at baseline, 16 [6-30] years) and 720 siblings self-reported PA and neurocognitive problems. PA was collected at baseline, and PA and neurocognitive data were obtained 7 (1-12) years and 12 (9-14) years later. PA consistency was defined as any combination of ≥ 75 minutes of vigorous or 150 minutes of moderate activity per week on all surveys. Multiple linear regressions, conducted separately for CNS and non-CNS survivors, identified associations between PA consistency and neurocognitive outcomes (expected mean, 50; standard deviation [SD], 10). Mediating effects of body mass index (BMI) and chronic health conditions (CHCs) were evaluated.

RESULTS

Survivors were less likely than siblings to report consistent PA (28.1% v 33.6%) and more likely to report problems in Task Efficiency (T-scores mean ± SD: siblings, 50.0 ± 0.4; CNS, 61.4 ± 0.4; non-CNS, 53.3 ± 0.3), Emotion Regulation (siblings, 51.4 ± 0.4; CNS, 54.5 ± 0.3; non-CNS 53.4 ± 0.2), and Memory (siblings, 50.8 ± 0.4; CNS, 58.9 ± 0.4; non-CNS, 53.5 ± 0.2; all P < .001). Survivors of CNS cancers (52.8 ± 0.3) also reported poorer Organization than siblings (49.9 ± 0.4; P < .001). After adjusting for age at diagnosis, age at questionnaire, emotional distress, and cancer treatment exposures, consistent PA was associated with fewer neurocognitive problems compared with consistent inactivity for both CNS and non-CNS groups (T-score differences ranging from -7.9 to -2.2) and larger neurocognitive improvements over time (-6.0 to -2.5), all P ≤ .01. BMI and severe CHCs partially mediated the PA-neurocognitive associations, but the mediation effects were small (change in β ≤ 0.4).

CONCLUSION

Adult survivors of childhood cancer who report more consistent PA have fewer neurocognitive problems and larger improvements in these concerns many years after treatment.

Fluoride exposure from infant formula and child IQ in a Canadian birth cohort

BACKGROUND

Infant consumption of formula reconstituted with fluoridated water can lead to excessive fluoride intake. We examined the association between fluoride exposure in infancy and intellectual ability in children who lived in fluoridated or non-fluoridated cities in Canada.

METHODS

We examined 398 mother-child dyads in the Maternal-Infant Research on Environmental Chemicals cohort who reported drinking tap water. We estimated water fluoride concentration using municipal water reports. We used linear regression to analyze the association between fluoride exposure and IQ scores, measured by the Wechsler Primary and Preschool Scale of Intelligence-III at 3-4 years. We examined whether feeding status (breast-fed versus formula-fed) modified the impact of water fluoride and if fluoride exposure during fetal development attenuated this effect. A second model estimated the association between fluoride intake from formula and child IQ.

RESULTS

Thirty-eight percent of mother-child dyads lived in fluoridated communities. An increase of 0.5 mg/L in water fluoride concentration (approximately equaling the difference between fluoridated and non-fluoridated regions) corresponded to a 9.3- and 6.2-point decrement in Performance IQ among formula-fed (95% CI: -13.77, -4.76) and breast-fed children (95% CI: -10.45, -1.94). The association between water fluoride concentration and Performance IQ remained significant after controlling for fetal fluoride exposure among formula-fed (B = -7.93, 95% CI: -12.84, -3.01) and breastfed children (B = -6.30, 95% CI: -10.92, -1.68). A 0.5 mg increase in fluoride intake from infant formula corresponded to an 8.8-point decrement in Performance IQ (95% CI: -14.18, -3.34) and this association remained significant after controlling for fetal fluoride exposure (B = -7.62, 95% CI: -13.64, -1.60).

CONCLUSIONS

Exposure to increasing levels of fluoride in tap water was associated with diminished non-verbal intellectual abilities; the effect was more pronounced among formula-fed children.

Association of water fluoride and urinary fluoride concentrations with attention deficit hyperactivity disorder in Canadian youth

BACKGROUND

Exposure to fluoride has been linked with increased prevalence of attention deficit hyperactivity disorder (ADHD) in the United States and symptoms of inattention in Mexican children. We examined the association between fluoride exposure and attention outcomes among youth living in Canada.

METHOD

We used cross-sectional data collected from youth 6 to 17 years of age from the Canadian Health Measures Survey (Cycles 2 and 3). Urinary fluoride concentration adjusted for specific gravity (UFSG) was available for 1877 participants. Water fluoride concentration measured in tap water samples was available for 980 participants. Community water fluoridation (CWF) status was determined by viewing reports on each city's website or contacting the water treatment plant. We used logistic regression to test the association between the three measures of fluoride exposure and ADHD diagnosis. Linear regression was used to examine the relationship between the three measures of fluoride exposure and the hyperactivity/inattention score on the Strengths and Difficulties Questionnaire (SDQ).

RESULTS

UF_SG did not significantly predict ADHD diagnosis or hyperactive/inattentive symptoms. A 1 mg/L increase in tap water fluoride level was associated with a 6.1 times higher odds of an ADHD diagnosis (95% CI = 1.60, 22.8). A significant interaction between age and tap water fluoride level (p = .03) indicated a stronger association between tap water fluoride and hyperactivity/inattention symptoms among older youth. A 1 mg/L increase in water fluoride level was associated with a 1.5 SDQ score increase (95% CI: 0.23, 2.68, p = .02) for youth at the 75th percentile of age (14 years old). Similarly, there was a significant interaction between age and CWF. At the 75th percentile of age (14 years old), those living in a fluoridated region had a 0.7-point higher SDQ score (95% CI = 0.34, 1.06, p < .01) and the predicted odds of an ADHD diagnosis was 2.8 times greater compared with youth in a non-fluoridated region (aOR = 2.84, 95% CI: 1.40, 5.76, p < .01).

DISCUSSION

Exposure to higher levels of fluoride in tap water is associated with an increased risk of ADHD symptoms and diagnosis of ADHD among Canadian youth, particularly among adolescents. Prospective studies are needed to confirm these results.

Factors associated with health care utilization in pediatric multiple sclerosis

BACKGROUND

We assessed whether clinical characteristics and health-related quality of life (HRQOL) are independently associated with subsequent hospitalizations and physician visits among children with multiple sclerosis (MS); and whether differences in HRQOL account for differences in physician visits between children with MS, monophasic acquired demyelinating syndromes (ADS) and healthy children.

METHODS

We used linked administrative (health) data from Ontario, Canada and data from a prospective cohort study including HRQOL (measured using the PedsQL), age, sex, cognitive function (accuracy and response time as assessed by Penn Neurocognitive Battery), number of relapses, and neurologic abnormalities on examination. We used generalized linear models with generalized estimating equations to examine factors associated with hospitalizations and ambulatory physician visit rates following each HRQOL assessment, adjusting for age, sex, and socioeconomic status.

RESULTS

We included 36 children with MS, 43 with monophasic ADS and 43 healthy controls. Among children with MS, more relapses were associated with increased odds of hospitalization (odds ratio 1.59; 1.18-2.14); better cognitive accuracy scores were associated with fewer physician visits (rate ratio [RR] 0.68; 0.47-0.98). Children with MS had higher rates of physician visits than healthy children (RR 1.44; 1.00-2.08), unlike children with a monophasic ADS, but HRQOL scores did not account for these differences.

CONCLUSION

Within the MS population, more relapses are associated with increased odds of hospitalization while better cognitive performance is associated with reduced rates of physician visits. Differences in HRQOL do not account for differences in physician visits by children with MS as compared to healthy children.

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

IMPORTANCE

The potential neurotoxicity associated with exposure to fluoride, which has generated controversy about community water fluoridation, remains unclear.

OBJECTIVE

To examine the association between fluoride exposure during pregnancy and IQ scores in a prospective birth cohort.

DESIGN, SETTING, AND PARTICIPANTS

This prospective, multicenter birth cohort study used information from the Maternal-Infant Research on Environmental Chemicals cohort. Children were born between 2008 and 2012; 41% lived in communities supplied with fluoridated municipal water. The study sample included 601 mother-child pairs recruited from 6 major cities in Canada; children were between ages 3 and 4 years at testing. Data were analyzed between March 2017 and January 2019.

EXPOSURES

Maternal urinary fluoride (MUFSG), adjusted for specific gravity and averaged across 3 trimesters available for 512 pregnant women, as well as self-reported maternal daily fluoride intake from water and beverage consumption available for 400 pregnant women.

MAIN OUTCOMES AND MEASURES

Children's IQ was assessed at ages 3 to 4 years using the Wechsler Primary and Preschool Scale of Intelligence-III. Multiple linear regression analyses were used to examine covariate-adjusted associations between each fluoride exposure measure and IQ score.

RESULTS

Of 512 mother-child pairs, the mean (SD) age for enrollment for mothers was 32.3 (5.1) years, 463 (90%) were white, and 264 children (52%) were female. Data on MUFSG concentrations, IQ scores, and complete covariates were available for 512 mother-child pairs; data on maternal fluoride intake and children's IQ were available for 400 of 601 mother-child pairs. Women living in areas with fluoridated tap water (n = 141) compared with nonfluoridated water (n = 228) had significantly higher mean (SD) MUFSG concentrations (0.69 [0.42] mg/L vs 0.40 [0.27] mg/L; P = .001; to convert to millimoles per liter, multiply by 0.05263) and fluoride intake levels (0.93 [0.43] vs 0.30 [0.26] mg of fluoride per day; P = .001). Children had mean (SD) Full Scale IQ scores of 107.16 (13.26), range 52-143, with girls showing significantly higher mean (SD) scores than boys: 109.56 (11.96) vs 104.61 (14.09); P = .001. There was a significant interaction (P = .02) between child sex and MUFSG (6.89; 95% CI, 0.96-12.82) indicating a differential association between boys and girls. A 1-mg/L increase in MUFSG was associated with a 4.49-point lower IQ score (95% CI, -8.38 to -0.60) in boys, but there was no statistically significant association with IQ scores in girls (B = 2.40; 95% CI, -2.53 to 7.33). A 1-mg higher daily intake of fluoride among pregnant women was associated with a 3.66 lower IQ score (95% CI, -7.16 to -0.14) in boys and girls.

CONCLUSIONS AND RELEVANCE

In this study, maternal exposure to higher levels of fluoride during pregnancy was associated with lower IQ scores in children aged 3 to 4 years. These findings indicate the possible need to reduce fluoride intake during pregnancy.

Abstract P1-11-04: Association between body mass index (BMI) and response to duloxetine for aromatase inhibitor (AI)-associated musculoskeletal symptoms (AIMSS)

Background: AIMSS occurs often in women treated with AI therapy for early stage breast cancer and can negatively impact adherence and persistence with therapy. Duloxetine is a serotonin norepinephrine reuptake inhibitor used to treat mood disorders and chronic pain. In SWOG S1202, patients with AIMSS treated with duloxetine reported statistically significant improvement in pain by 12 weeks compared to placebo. Obesity is a predictor of increased likelihood of developing AIMSS, and a prior study of omega 3 fatty acid versus placebo for AIMSS showed a potential differential response to therapy by BMI. In this exploratory analysis of S1202, we investigated the association between baseline BMI and response to therapy.

Methods: In S1202, 299 postmenopausal women with stage I-III hormone receptor-positive breast cancer on AI therapy who developed new or worsening average pain of 4-10 on a numerical rating scale were enrolled, randomized 1:1 to duloxetine or placebo with randomization stratified by baseline pain (4-6 vs. 7-10) and prior taxane therapy (yes vs. no). Patients were treated for 12 weeks. Patient-reported outcomes including Brief Pain Inventory (BPI) were obtained at baseline and weeks 2, 6, 12, and 24. Patients were categorized into BMI&lt;30 kg/m2 (non-obese) or BMI≥30 kg/m2 (obese). The pre-specified aim of this secondary analysis was to examine whether the effect of intervention on BPI average pain at 12 weeks differed between obese and non-obese patients. Multiple linear regression was used, adjusting for the stratification factors and the baseline score. We tested whether the interaction of BMI status and intervention effect was statistically significant at α=.05.

Results: 289 patients were eligible for the analysis, 54% of whom were obese. The cohorts were well balanced other than by race. The difference by intervention arm in the 12-week mean BPI scores between baseline and follow-up scores was substantially different for the obese versus non-obese cohorts. In the patients with BMI&lt;30, the reduction in observed mean average pain score was similar in the duloxetine- and placebo-treated patients (-2.46 points vs. -2.34 points, p=.75). In contrast, in the patients with BMI≥30 the reduction in pain score was statistically significantly greater for the duloxetine-treated compared to the placebo-treated patients (-2.73 points vs. -1.64 points, p=.003; interaction p-value=.02). Differences in intervention effects between obese and non-obese groups were even stronger at 2-weeks (interaction p-value=.001) and 6-weeks (interaction p-value&lt;.0001). Similar findings were evident for other pain-related patient-reported outcomes.

Conclusions: In the placebo-controlled S1202 trial, obese patients with AIMSS obtained more analgesic benefit from duloxetine. Additional studies are warranted to determine the biologic basis for these findings, such as a different mechanism underlying development of AIMSS or pain expression in patients with obesity, or other confounding variables related to analgesic response to duloxetine relative to placebo.

Support: NIH/NCI grants CA189974, CA189821, CA180820; and in part by Damon Runyon-Lilly Clinical Investigator Award #CI-53-10 [to NLH], and in part by Lilly USA, LLC.

Citation Format: Henry NL, Unger JM, Till C, Schott AF, Crew KD, Lew DL, Fisch MJ, Moinpour CM, Wade JL, Hershman DL. Association between body mass index (BMI) and response to duloxetine for aromatase inhibitor (AI)-associated musculoskeletal symptoms (AIMSS) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-11-04.

Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico City

BACKGROUND

Epidemiologic and animal-based studies have raised concern over the potential impact of fluoride exposure on neurobehavioral development as manifested by lower IQ and deficits in attention. To date, no prospective epidemiologic studies have examined the effects of prenatal fluoride exposure on behavioral outcomes using fluoride biomarkers and sensitive measures of attention.

OBJECTIVE

We aimed to examine the association between prenatal fluoride exposure and symptoms associated with attention-deficit/hyperactivity disorder (ADHD).

METHOD

213 Mexican mother-children pairs of the Early Life Exposures to Environmental Toxicants (ELEMENT) birth cohort study had available maternal urinary samples during pregnancy and child assessments of ADHD-like behaviors at age 6-12. We measured urinary fluoride levels adjusted for creatinine (MUF_cr) in spot urine samples collected during pregnancy. The Conners' Rating Scales-Revised (CRS-R) was completed by mothers, and the Conners' Continuous Performance Test (CPT-II) was administered to the children.

RESULTS

Mean MUF_cr was 0.85 mg/L (SD = 0.33) and the Interquartile Range (IQR) was 0.46 mg/L. In multivariable adjusted models using gamma regression, a 0.5 mg/L higher MUF_cr (approximately one IQR higher) corresponded with significantly higher scores on the CRS-R for DSM-IV Inattention (2.84 points, 95% CI: 0.84, 4.84) and DSM-IV ADHD Total Index (2.38 points, 95% CI: 0.42, 4.34), as well as the following symptom scales: Cognitive Problems and Inattention (2.54 points, 95% CI: 0.44, 4.63) and ADHD Index (2.47 points; 95% CI: 0.43, 4.50). The shape of the associations suggested a possible celling effect of the exposure. No significant associations were found with outcomes on the CPT-II or on symptom scales assessing hyperactivity.

CONCLUSION

Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention as measured by the CRS-R in the offspring.

Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status

BACKGROUND

Fluoride exposure has the potential to disrupt thyroid functioning, though adequate iodine intake may mitigate this effect. This is the first population-based study to examine the impact of chronic low-level fluoride exposure on thyroid function, while considering iodine status. The objective of this study was to determine whether urinary iodine status modifies the effect of fluoride exposure on thyroid stimulating hormone (TSH) levels.

METHODS

This cross-sectional study utilized weighted population-based data from Cycle 3 (2012-2013) of the Canadian Health Measures Survey (CHMS). Information was collected via a home interview and a visit to a mobile examination centre. The weighted sample represented 6,914,124 adults in Canada aged 18-79 who were not taking any thyroid-related medication. Urinary fluoride concentrations were measured in spot samples using an ion selective electrode and adjusted for specific gravity (UF_SG). Serum TSH levels provided a measure of thyroid function. Multivariable regression analyses examined the relationship between UF_SG and TSH, controlling for covariates.

RESULTS

Approximately 17.8% of participants fell in the moderately-to-severely iodine deficient range. The mean (SD) age of the sample was 46.5 (15.6) years and the median UF_SG concentration was 0.74 mg/L. Among iodine deficient adults, a 1 mg/L increase in UF_SG was associated with a 0.35 mIU/L increase in TSH [95% CI: 0.06, 0.64; p = 0.01, one-tailed].

CONCLUSIONS

Adults living in Canada who have moderate-to-severe iodine deficiencies and higher levels of urinary fluoride may be at an increased risk for underactive thyroid gland activity.

Assessment of neuropsychological performance in Mexico City youth using the Cambridge Neuropsychological Test Automated Battery (CANTAB)

BACKGROUND

The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a computerized tool used to measure cognitive function in diverse populations and is sensitive for assessing developmental changes in children. Although CANTAB has been used in several countries, its applicability in a Mexican child population is unknown. This study examined developmental trends on CANTAB in a large sample of urban Mexico City youth and tested the hypothesis that their performance would be similar to a large US normative sample.

METHOD

As part of a birth cohort, Early Life Exposures in Mexico to Environmental Toxicants, 826 children, ages 5-15 years, completed CANTAB. Subtests measured planning (Stockings of Cambridge; SOC), short-term memory (Delayed Matching to Sample; DMS), sustained attention (Rapid Visual Information Processing; RVP), ability to match visual stimuli (Match to Sample Visual Search; MTS), flexibility (Intra-extra Dimensional Set Shift; IED), and response inhibition (Stop Signal Task; SST). Determinants of performance on the CANTAB, including age, maternal/child IQ, and sex, were analyzed using Spearman correlation and Welch t tests. Equivalence testing compared performance with existing norms.

RESULTS

Performance improved with age on all measures. Child IQ was mildly associated with measures of memory and attention but not executive functioning, consistent with US norms. Maternal IQ was not associated with any outcomes, and males performed better on IED. Mexican norms were comparable to US norms on almost all outcomes, with the exception of a short-term visual recognition memory task (DMS).

CONCLUSIONS

This study provides the largest normative data for CANTAB performance in a community sample of Mexican youth. Findings demonstrate the expected maturational effects of executive function, specifically in cognitive shifting and inhibition. Levels of executive function performance demonstrated by a Mexican sample were consistent with normative values reported in US youth. These findings, as well as expected associations with child IQ, indicate high applicability of CANTAB for Mexican youth in neurobehavioral studies.

Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada

BACKGROUND

Fluoride exposures have not been established for pregnant women who live in regions with and without community water fluoridation.

OBJECTIVE

Our aim was to measure urinary fluoride levels during pregnancy. We also assessed the contribution of drinking-water and tea consumption habits to maternal urinary fluoride (MUF) concentrations and evaluated the impact of various dilution correction standards, including adjustment for urinary creatinine and specific gravity (SG).

METHODS

We measured MUF concentrations in spot samples collected in each trimester of pregnancy from 1,566 pregnant women in the Maternal-Infant Research on Environmental Chemicals cohort. We calculated intraclass correlation coefficients (ICCs) to assess variability in MUF concentrations across pregnancy. We used regression analyses to estimate associations between MUF levels, tea consumption, and water fluoride concentrations as measured by water treatment plants.

RESULTS

Creatinine-adjusted MUF values ([Formula: see text]; milligrams per liter) were almost two times higher for pregnant women living in fluoridated regions ([Formula: see text]) compared with nonfluoridated regions ([Formula: see text]; [Formula: see text]). MUF values tended to increase over the course of pregnancy using both unadjusted values and adjusted values. Reproducibility of the unadjusted and adjusted MUF values was modest ([Formula: see text]). The municipal water fluoride level was positively associated with creatinine-adjusted MUF ([Formula: see text], 95% CI: 0.46, 0.57), accounting for 24% of the variance after controlling for covariates. Higher MUF concentrations correlated with numbers of cups of black ([Formula: see text] but not green tea ([Formula: see text]). Urinary creatinine and SG correction methods were highly correlated ([Formula: see text]) and were interchangeable in models examining predictors of MUF.

CONCLUSION

Community water fluoridation is a major source of fluoride exposure for pregnant women living in Canada. Urinary dilution correction with creatinine and SG were shown to be interchangeable for our sample of pregnant women. https://doi.org/10.1289/EHP3546.

Involvement of the Amygdala in Memory and Psychosocial Functioning in Pediatric-Onset Multiple Sclerosis

Youth with multiple sclerosis (MS) often experience cognitive impairment and psychosocial disturbances. We describe the relationship between memory function, psychosocial skills, and brain volume in 32 patients with pediatric-onset MS and 30 controls. Amygdala volume was significantly lower in patients compared with controls. In general, poorer memory was associated with reduced functional communication skills and reduced amygdala volume. Greater amygdala volume in patients correlated with parent-reported functional communication and social skills. Adjusting for whole-brain volume, right amygdala volume was positively associated with visual memory; left amygdala volume was a stronger predictor of parent-reported social skills.

Detection and clinical correlation of leukocortical lesions in pediatric-onset multiple sclerosis on multi-contrast MRI

Objective:

To determine the frequency of cortical lesions (CLs) in patients with pediatric-onset multiple sclerosis (POMS) using multi-contrast magnetic resonance imaging (MRI), and the relationship between frontal CL load and upper limb dexterity assessed with the Nine-Hole Peg Test (9-HPT).

Methods:

Participants completed the 9-HPT and were imaged on a 3T MRI scanner to collect T1-weighted three-dimensional (3D) magnetization prepared rapid gradient echo (MPRAGE), proton density–weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. CLs were manually segmented using all MRI contrasts.

Results:

We enrolled 24 participants with POMS (mean (standard deviation) age at first symptom: 13.3 (±2.7) years; mean age at scan: 18.8 (±3) years; mean disease duration of 5 (±3.2) years). A total of 391 CLs (mean, 16.3 ± 27.2; median, 7) were identified in 19 of 24 POMS patients (79%). The total number of CLs was positively associated with white matter lesion volume ( p = 0.04) but not with thalamic volume, age at the time of the scan, or disease duration. The number of frontal CLs was associated with slower performance on the 9-HPT ( p = 0.05).

Conclusion:

Multi-contrast 3T MRI led to a high rate of CL detection, demonstrating that cortical pathology occurs even in pediatric-onset disease. Frontal lobe CL count was associated with reduced manual dexterity, indicating that these CLs are clinically relevant.

Abstract P6-12-09: Association between cardiovascular risk factors and cardiac events among breast cancer patients enrolled in SWOG clinical trials

Background: Due to early detection and improved treatments, women with breast cancer are living longer. Breast cancer shares risk factors with cardiovascular disease (CVD), and its treatments have adverse cardiovascular effects. Less is known about the association between cardiac risk factors and long-term cardiac events among the patients enrolled in breast cancer trials, as most trials fail to collect this information.

Methods: We examined the SWOG database to identify phase II/III breast cancer trials from 1999-2011. Among patients over 65 years, we linked the SWOG clinical records to Medicare claims data according to social security number and date of birth. This analysis included patients with 6+ months of Medicare coverage prior to baseline and 12+ months of Medicare coverage at any point after baseline. The comorbidities investigated at baseline were diabetes, hypertension, hypercholesterolemia, coronary artery/ischemic heart disease and obesity. A cardiac event was defined as an acute ischemic event or acute heart failure. Cox regression was used to calculate time-to-event, stratified by study ID and adjusted for baseline age, race, and prognostic risk score. Cox regression was performed separately for each CVD risk factor, and an additional analysis was performed to assess the impact of having multiple concurrent risk factors. Secondary analyses were performed separately by study type (Adjuvant, Advanced).

Results: Among patients linked to Medicare included in this cohort (N=742), the median age was 70, and median follow-up was 6 years. The majority of patients were non-Hispanic white. The most prevalent conditions were hypercholesterolemia (58%) and hypertension (73%). Only 13% had no baseline risk CVD factors. In a Cox regression, all baseline risk factors except hypercholesterolemia and obesity were statistically significantly or borderline statistically significantly associated with an increased risk of eventual cardiac event, and for ischemic heart disease the increased risk was more than two-fold (HR=2.27, 95% CI=1.46-3.54, p=0.0003) and for baseline diabetes nearly two-fold (HR=1.75, 95% CI=1.13-2.71, p=0.01). In addition, there was evidence of a linear association of number of concurrent risk factors and cardiac events (HR per additional risk factor = 1.35 (1.09-1.66), p=0.005). In the stratified analysis, the associations were statistically significant only for participants on adjuvant studies. No association between baseline cardiac risk factors and cardiovascular outcomes were seen among patients with advanced cancer.

Conclusions:In summary, we found that even among healthy breast cancer patients selected for clinical trials, baseline CVD risk factors are associated with an increased risk of cardiac events, however this association was not observed for patients with advanced disease, who are more likely to die from breast cancer before experiencing a cardiovascular event.

Citation Format: Hershman DL, Till C, Wright JD, Ramsey SD, Barlow WE, Unger JM. Association between cardiovascular risk factors and cardiac events among breast cancer patients enrolled in SWOG clinical trials [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-12-09.

A feasibility study of working memory training for individuals with paediatric-onset multiple sclerosis

Objective: To investigate the feasibility and experiences of paediatric-onset multiple sclerosis (MS) patients completing a working memory training programme. Methods: Nine paediatric-onset MS patients (mean age 19.3 ± 4.1 years) identified as having attention and/or working memory difficulties underwent a five-week (five days/week) internet-based working memory training programme (Cogmed™); weekly coaching was provided. Measures of adherence and tolerance were used to establish the feasibility of implementing computerised cognitive training. Qualitative experiences reported by the patients were analysed and factors that may modulate the effects of training were explored. Results: Six of the nine enrolled patients completed the programme within the recommended time, and all individuals, with the exception of one, were considered to tolerate the training well. Eight of the nine participants acknowledged that training was helpful in one or more ways. All but one participant reported improvements in working memory, although evidence for improvement on objective neuropsychological testing was limited. Lower normalised brain volume emerged as a potentially important variable in predicting extent of improvement on the training programme. Conclusion: Selected paediatric-onset MS patients can tolerate and complete an intensive cognitive rehabilitation programme. Future investigation of moderators of training effects and the stability of the findings over time is needed.

Altered resting-state functional connectivity in cognitively preserved pediatric-onset MS patients and relationship to structural damage and cognitive performance

OBJECTIVE

To evaluate resting-state functional connectivity (FC) and relationship to brain volumes and cognition in a sample of cognitively preserved pediatric-onset multiple sclerosis (MS) patients.

METHODS

Sixteen cognitively intact pediatric-onset MS patients and 15 healthy age- and sex-matched controls underwent cognitive testing and 3T anatomical and functional MRI. Resting-state FC patterns were examined using region-of-interest-based timeseries correlations.

RESULTS

Compared to controls, pediatric-onset MS patients demonstrated higher FC of the precuneus, particularly with the anterior cingulate cortex (z=4.21, p<.001), frontal medial cortex (z=3.48, p<.001), and cerebellum (z=3.72, p<.001). Greater T2 lesion volume and lower normalized thalamic volume were associated with reduced FC of the thalamus, especially for FC with the right superior occipital region (t=-2.87, p=.0123 and t=2.27, p=.04 respectively). FC of the left frontal medial cortex was negatively correlated with composite cognitive z-score in the pediatric-onset MS group (p<.05).

CONCLUSIONS

Greater resting-state FC between posterior and anterior brain regions is present in pediatric-onset MS. With greater disease-related structural pathology, there is a disruption of thalamo-cortical FC. In the absence of actual cognitive impairment, heightened FC of the frontal medial cortex was associated with lower cognitive performance, suggesting that greater functional resources are recruited during resting-state in patients with reduced cognitive efficiency.