Publications by authors named "Nadine Forget-Dubois"

31 Publications

Developing a quality curriculum in a technological era.

Educ Technol Res Dev 2020 Nov 11:1-24. Epub 2020 Nov 11.

Université Laval, Department of Foundations and Practices in Education, Québec, QC Canada.

There is considerable rhetoric internationally around the need for national curricula to reflect the changes that are taking place in the world outside school. This raises questions about what a quality curriculum in a technological era should look like, and equally challenging issues about how to achieve the necessary changes in schooling in order for such a curriculum to be realised. This paper summarises the views of 11 experts from seven countries. It introduces a sociocultural framework that highlights the complexity of achieving alignment between policies and practice spanning the national to local school to classroom levels. Three key issues that underpin alignment are then explored, each of which link with the issue of trust:stakeholders engagement;teacher professionalism;summative assessment. By exploring and exemplifying these three issues the paper indicates potential ways of addressing them and provides 'tools to think with' to enhance future curriculum development initiatives.
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http://dx.doi.org/10.1007/s11423-020-09857-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7657067PMC
November 2020

Effects of polychlorinated biphenyls exposure on physical growth from birth to childhood and adolescence: A prospective cohort study.

Environ Res 2020 10 11;189:109924. Epub 2020 Jul 11.

Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec, Canada; École de Psychologie, Université Laval, Québec, Québec, Canada. Electronic address:

Background/aims: Given that their traditional lifestyle and diet still relies on fish and other marine species for sustenance, the Inuit are highly exposed to polychlorinated biphenyls (PCBs) and PCBs are increasingly linked to obesity. However, evidence is not consistent regarding which periods of exposure are most relevant. In this study, we examine whether in utero, childhood, and adolescent exposure to PCBs are related to physical growth at adolescence.

Method: Inuit adolescents from Canada (N=212) enrolled in a prospective longitudinal cohort study since birth were assessed for height, weight, body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI) at 18 years of age. PCB 153 concentrations were quantified in blood samples obtained at birth (umbilical cord), 11, and 18 years of age. Maternal anthropometrics were measured and those for the newborns collected from medical records. Data on biological mothers and participants' sociodemographic characteristics and food security were collected using interviews. Multiple linear regression analyses were used to test associations between PCB 153 concentrations and adolescent anthropometric measures.

Results: Cord PCB 153 was not related to height or FFMI at adolescence. By contrast, analyses showed that cord PCB 153 was related to higher BMI, FMI and marginally to weight in girls but not boys. Child PCB 153 was not related to height, weight or FFMI in adolescence. Child PCB 153 was related to lower BMI and FMI at adolescence in both sexes, particularly among those considered overweight or obese during childhood. Adolescent PCB 153 was not associated with any outcome.

Conclusion: This study suggests that prenatal exposure to PCBs may have a long-term effect on growth in early adulthood among girls and identifies the peri-pubertal period as another window of sensitivity for the action of PCBs. Our findings also suggest that exposure to PCBs and body size be documented in multiple time periods from infancy to adulthood.
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http://dx.doi.org/10.1016/j.envres.2020.109924DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7529953PMC
October 2020

Food insecurity and psychological distress in Inuit adolescents of Nunavik.

Public Health Nutr 2020 10 27;23(14):2615-2625. Epub 2020 May 27.

Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, Canada.

Objective: The present study aims at measuring the association between household food insecurity and psychological distress in adolescents in Inuit communities, concurrently and overtime from childhood to adolescence.

Design: The study used measures of internalising behaviours (anxiety, withdrawn attitude, somatic complaints and depression) as indicators of psychological distress during adolescence, a concurrent measure of household food insecurity in adolescence and an assessment of longitudinal patterns of household food insecurity from childhood to adolescence. We collected descriptive information at birth, childhood and adolescence on potential confounders.

Setting: Inuit communities of Nunavik in northern Quebec, Canada.

Participants: The study consisted of 212 participants from the Nunavik Child Development Study, who have been assessed at birth, childhood (mean age = 11 years, range = 9-13 years) and adolescence (mean age = 18 years, range = 16-21 years).

Results: Concurrent severe household food insecurity in adolescence was associated with higher measures of psychological distress: depression (βstd = 0·26, P < 0·01) and withdrawn attitude (βstd = 0·20, P = 0·04). Persistent household food insecurity (both at childhood and adolescence) was associated with higher levels of adolescent depression (βstd = 0·18, P = 0·02) and anxiety (βstd = 0·17, P = 0·03).

Conclusions: Adolescents from Nunavik living with higher food insecurity and those having experienced food insecurity in both childhood and adolescence were more likely to report symptoms of psychological distress. Considering the high level of distress experienced by young Inuit, existing initiatives to reduce food insecurity in Nunavik communities should be targeted to include children and adolescents.
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http://dx.doi.org/10.1017/S1368980020000117DOI Listing
October 2020

Gestational Exposures to Phthalates and Folic Acid, and Autistic Traits in Canadian Children.

Environ Health Perspect 2020 02 19;128(2):27004. Epub 2020 Feb 19.

Centre Hospitalier Universitaire (CHU) de Québec Research Centre and School of Psychology, Laval University, Quebec, Quebec, Canada.

Background: The etiology of autism spectrum disorder is poorly understood. Few studies have investigated the link between endocrine-disrupting chemicals and autistic traits. We examined the relationship between gestational phthalates and autistic traits in 3- to 4-y-old Canadian children. We also investigated potential effect modification by sex and folic acid supplementation.

Methods: We enrolled 2,001 of age during the first trimester of pregnancy between 2008 and 2011 from 10 cities in Canada. At 3-4 years of age, 610 children underwent neuropsychological assessments including the Social Responsiveness Scale-II (SRS-2) as a measure of autistic traits and social impairment. We measured 11 phthalate metabolites in maternal first trimester urine samples and assessed folic acid supplementation from reported intakes. We estimated covariate-adjusted differences in SRS-2 -scores with a doubling in phthalate concentrations in 510 children with complete data.

Results: Mean total SRS -score was 45.3 (). Children with higher gestational exposure to mono--butyl (MBP) and mono-3-carboxypropyl (MCPP) concentrations exhibited significantly higher total SRS -scores, indicating greater overall social impairment, as well as higher scores on subdomains, indicating deficits in social cognition, social communication, social motivation, and restricted interests/repetitive behaviors. A doubling in MBP or MCPP concentrations was associated with 0.6 (95% CI: 0.1, 1.0) and 0.5 (95% CI: 0.1, 0.8) higher total SRS -scores. Associations were consistently and significantly stronger in boys (; 95% CI: 0.4, 1.6; ) compared with girls (; 95% CI: , 0.7; ) and among children who had lower prenatal folic acid supplementation () (; 95% CI: 0.4, 2.3; ) compared with those who had adequate folic acid supplementation () (; 95% CI: , 0.8; ).

Conclusions: Higher gestational concentrations of some phthalate metabolites were associated with higher scores of autistic traits as measured by the SRS-2 in boys, but not girls; these small size effects were mitigated by first trimester-of-pregnancy folic acid supplementation. https://doi.org/10.1289/EHP5621.
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http://dx.doi.org/10.1289/EHP5621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064316PMC
February 2020

Association between early lead exposure and externalizing behaviors in adolescence: A developmental cascade.

Environ Res 2019 11 19;178:108679. Epub 2019 Aug 19.

Centre de Recherche du CHU de Québec-Université Laval, Québec, Québec, Canada; École de Psychologie, Université Laval, Québec, Québec, Canada. Electronic address:

Background: Lead (Pb) exposure is associated with adverse neurological development. Most notably, it has been observed through externalizing behavior symptoms, as observed among Inuit children from northern Québec. Evidence for a persistent neurological impact of early Pb exposure later in life is however scarce. Pb exposure may initiate a developmental cascade that increases the risk of long-term behavior problems.

Objectives: Testing for direct associations between childhood Pb concentrations and adolescent externalizing symptoms and substance use, as well as indirect associations through childhood behavior assessments.

Methods: The study sample is a longitudinal cohort of Inuit children (n = 212) followed since birth. Blood Pb concentrations were measured during childhood (median age = 11.4 years) and adolescence (median age = 18.5 years). Externalizing/inattentive behavior were teacher-assessed through the Teacher Report Form and the Disruptive Behavior Disorders Rating Scale for children. At the adolescence follow-up, behavior problems were self-reported by filling Achenbach's Youth Self-Report, the Barkley Adult ADHD-IV Rating Scale, and the Diagnostics Interview Schedule for Children. Adolescent substance use was also self-assessed through the DEP-ADO. Direct and indirect associations of child Pb concentrations with adolescent outcomes were tested through mediation models.

Results: Child blood Pb concentrations were not directly associated with any adolescent outcomes. On the contrary, childhood Pb exposure was indirectly associated, through childhood externalizing behavior assessments, with adolescent externalizing behaviors, binge drinking, and cannabis use. These indirect associations held after controlling for adolescents' concurrent Pb blood concentrations.

Discussion: Our results highlight the indirect but lasting effects of child Pb exposure on adolescent behavior problems, and the importance of childhood externalizing behavior in this relationship. Adverse early-life environment put children on a riskier developmental trajectory, increasing their likelihood of lifelong psychological, social and health problems.
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http://dx.doi.org/10.1016/j.envres.2019.108679DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759380PMC
November 2019

Prenatal and childhood exposure to chlordecone and sex-typed toy preference of 7-year-old Guadeloupean children.

Environ Sci Pollut Res Int 2020 Nov 1;27(33):40971-40979. Epub 2019 Jul 1.

Centre de recherche du CHU de Québec-Université Laval and École de psychologie, Université Laval, Québec, Canada.

Chlordecone was used intensively as an insecticide in the French West Indies. Because of its high persistence, the resulting contamination of food and water has led to chronic exposure of the general population as evidenced by its presence in the blood of people of Guadeloupe, in particular in pregnant women and newborns, and in maternal breast milk. Chlordecone is recognized as a reproductive and developmental toxicant, is neurotoxic and carcinogenic in rodents, and is considered as an endocrine-disrupting compound with well-established estrogenic and progestogenic properties both in vitro and in vivo. The question arises of its potential consequences on child neurodevelopment following prenatal and childhood exposure, in particular on behavioral sexual dimorphism in childhood. We followed 116 children from the TIMOUN mother-child cohort study in Guadeloupe, who were examined at age 7. These children were invited to participate in a 7-min structured play session in which they could choose between different toys considered as feminine, masculine, or neutral. The play session was video recorded, and the percentage of the time spent playing with feminine or masculine toys was calculated. We estimated associations between playtime and prenatal exposure to chlordecone (assessed by concentration in cord blood) or childhood exposure (determined from concentrations in child blood obtained at the 7-year follow-up), taking into account confounders and co-exposures to other environmental chemicals. We used a two-group regression model to take into account sex differences in play behavior. Our results do not indicate any modification in sex-typed toy preference among 7-year-old children in relation with either prenatal or childhood exposure to chlordecone.
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http://dx.doi.org/10.1007/s11356-019-05686-xDOI Listing
November 2020

The Genetic and Environmental Etiology of Shyness Through Childhood.

Behav Genet 2019 07 15;49(4):376-385. Epub 2019 Mar 15.

School of Psychology, Université Laval, Québec City, QC, G1V 0A6, Canada.

The objective of this study was to examine the genetic and environmental contributions to shyness throughout the school-age period. Participants were 553 twin pairs from the ongoing prospective longitudinal Quebec Newborn Twin Study. Teacher-rated measures of shyness were collected at five time-points from age 6-12 years. On average, shyness was moderately stable over time (r = 0.23-0.33) and this stability was almost entirely accounted for by genetic factors. Genetic factors at age 6 accounted for 44% of individual differences and these early genetic factors also explained individual differences at all subsequent ages (6-22%). Non-shared environmental factors explained most of individual differences at single time-points (51-63%), and did not account for stability in shyness. Contributions of shared environment were not significant. Our results suggest that the stability in shyness is mostly accounted for by early and persistent genetic contributions.
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http://dx.doi.org/10.1007/s10519-019-09955-wDOI Listing
July 2019

Prenatal, concurrent, and sex-specific associations between blood lead concentrations and IQ in preschool Canadian children.

Environ Int 2018 12 2;121(Pt 2):1235-1242. Epub 2018 Nov 2.

Centre de recherche du Centre Hospitalier Universitaire de Québec, Québec, Canada; École de psychologie, Université Laval, Quebec, Québec, Canada. Electronic address:

Background: Lead exposure predicts altered neurodevelopment and lower intelligence quotient (IQ) in children, but few studies have examined this association in children who have relatively low blood lead concentrations.

Objectives: To test the associations between blood lead concentrations and cognitive function in Canadian preschoolers, with a possible moderation by sex.

Methods: The data were gathered from 609 mother-child pairs from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. Lead was measured in umbilical and maternal blood, and in children's venous blood at age 3-4 years. Cognitive function was measured with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) at 3-4 years. We tested the relationship between WPPSI-III scores and blood lead concentrations with multiple linear regression, adding child sex as a moderator.

Results: Median blood lead concentrations for the mother at 1st trimester and 3rd trimester of pregnancy, and for cord and child blood were 0.60 μg/dL, 0.58 μg/dL, 0.79 μg/dL and 0.67 μg/dL, respectively. We found no association between cord blood lead concentrations and WPPSI-III scores in multivariable analyses. However, cord blood lead concentrations showed a negative association with Performance IQ in boys but not in girls (B = 3.44; SE = 1.62; 95% CI: 0.82, 5.98). No associations were found between WPPSI-III scores and prenatal maternal blood or concurrent child blood lead concentrations.

Conclusions: Prenatal blood lead concentrations below 5 μg/dL were still associated with a decline in cognitive function in this Canadian cohort, but only for boys.
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http://dx.doi.org/10.1016/j.envint.2018.10.043DOI Listing
December 2018

Household overcrowding and psychological distress among Nunavik Inuit adolescents: a longitudinal study.

Int J Circumpolar Health 2018 12;77(1):1541395

b Department of Geography , McGill University , Montréal , Canada.

About half of Nunavik Inuit live in overcrowded households compared to very few Canadians from the general population. Living in overcrowded households is associated with greater risks of suffering from mental health problems for Canadian adolescents. The present work aims at studying prospectively the hypothesised relationship between household overcrowding at childhood and psychological distress during adolescence among Nunavik Inuit, as well as the hypothesised relationship between these phenomena when they are both measure at adolescence. Recruited as part of the Nunavik Child Development Study, 220 participants were met at 11 years old in average and then when they were 18 years old in average. Household overcrowding was assessed using the people per room ratio. Psychological distress symptoms were operationalised at adolescence using depressive symptoms and suicidal thoughts. The results did not show that childhood household crowding had a long-term effect on psychological distress. An absence of moderation by sex of the association was also found in the present study. Despite those results, household crowding could be a risk factor only when in interaction with other elements related with poverty or housing or could be experienced as a difficulty for adolescents on other aspects than depressive symptoms and suicidal thoughts.
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http://dx.doi.org/10.1080/22423982.2018.1541395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6225517PMC
December 2018

Heritability of obsessive-compulsive trait dimensions in youth from the general population.

Transl Psychiatry 2018 09 18;8(1):191. Epub 2018 Sep 18.

Genetics and Genome Biology, Hospital for Sick Children, Toronto, Canada.

Obsessive-compulsive disorder (OCD) is a heritable childhood-onset psychiatric disorder that may represent the extreme of obsessive-compulsive (OC) traits that are widespread in the general population. We report the heritability of the Toronto Obsessive-Compulsive Scale (TOCS), a new measure designed to assess the complete range of OC traits in youth. We also examined the dimensional nature of the TOCS and the degree to which genetic effects are unique or shared between dimensions. OC traits were measured using the TOCS in 16,718 youth (6-18 years) at a science museum. We conducted a factor analysis to identify OC trait dimensions. We used univariate and multivariate twin models to estimate the heritability of OC trait dimensions in a subset of twins (220 pairs). Six OC dimensions were identified: Cleaning/Contamination, Symmetry/Ordering, Rumination, Superstition, Counting/Checking, and Hoarding. The TOCS total score (74%) and each OC dimension was heritable (30-77%). Hoarding was not highly correlated with other OC dimensions, but did share genetic effects. Shared genetics accounted for most of the shared variance among dimensions, whereas unique environment accounted for the majority of dimension-specific variance. One exception was Hoarding, which had considerable unique genetic factors. A latent trait did not account for the shared variance between dimensions. In conclusion, OC traits and individual OC dimensions were heritable, although the degree of shared and dimension-specific etiological factors varied by dimension. The TOCS may be informative for genetic research of OC traits in youth. Genetic research of OC traits should consider both OC dimension and total trait scores.
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http://dx.doi.org/10.1038/s41398-018-0249-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6143601PMC
September 2018

Prenatal exposure to polybrominated diphenyl ethers and predisposition to frustration at 7 months: Results from the MIREC study.

Environ Int 2018 10 22;119:79-88. Epub 2018 Jun 22.

Centre de Recherche du CHU de Québec-Université Laval, Québec, Qc, Canada; École de Psychologie, Université Laval, Québec, Qc, Canada.

Background: Prenatal exposure to polybrominated diphenyl ethers (PBDEs) has been associated with cognitive deficits and behavioral problems in children. To date, no study has examined this exposure in association with neurobehavioral development in infants younger than 12 months assessed with observational tasks.

Objectives: This study examined the relation between prenatal PBDE concentrations and predisposition to frustration, assessed by the arm restraint task (ART), in Canadian infants.

Methods: In a prospective longitudinal study conducted in Canada, exposure to nine PBDE congeners was measured in maternal plasma during the first trimester of pregnancy. The ART was used to measure predisposition to frustration in infancy (N = 333; mean age = 6.9 months), as assessed by negative vocalizations (crying and screaming) and physical reactivity (discomfort movements).

Results: Maternal plasma PBDE-47 concentrations collected during pregnancy were associated with negative vocalizations using the ART (adjusted Relative Risk [aRR] = 1.04, 95% CI: 1.00, 1.09). Prenatal PBDE-99 concentrations during pregnancy were also related to a shift to the left in the tail of the distribution of onset of negative vocalizations as measured by a decrease of 38 s (95% CI: -78.1, 1.3) in the 75th quantile of the distribution for infants whose mothers had detectable levels of PBDE-99 compared to infants of mothers with undetectable levels. Similarly, infants whose mothers had detectable levels of PBDE-100 showed an increase of 24.1 s (95% CI: 4.1, 44.1) in the 75th quantile of the distribution of proportion of time in negative vocalizations compared with infants of mothers with undetectable levels. Finally, the association between PBDE-47 and PBDE-153, and physical reactivity was significantly modified by sex (p < 0.1), with opposite patterns in girls and boys.

Conclusions: Prenatal exposure to PBDEs was associated with increased incidence of crying and screaming with delayed onset of discomfort movement, which may indicate a predisposition to frustration and lack of habituation in infants younger than 12 months from the general population.
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http://dx.doi.org/10.1016/j.envint.2018.06.010DOI Listing
October 2018

Why children differ in motivation to learn: Insights from over 13,000 twins from 6 countries.

Pers Individ Dif 2015 Jul;80:51-63

Université de Montréal, Montréal, Canada.

Little is known about why people differ in their levels of academic motivation. This study explored the etiology of individual differences in enjoyment and self-perceived ability for several school subjects in nearly 13,000 twins aged 9-16 from 6 countries. The results showed a striking consistency across ages, school subjects, and cultures. Contrary to common belief, enjoyment of learning and children's perceptions of their competence were no less heritable than cognitive ability. Genetic factors explained approximately 40% of the variance and all of the observed twins' similarity in academic motivation. Shared environmental factors, such as home or classroom, did not contribute to the twin's similarity in academic motivation. Environmental influences stemmed entirely from individual specific experiences.
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http://dx.doi.org/10.1016/j.paid.2015.02.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4372262PMC
July 2015

Impact of Inuit customary adoption on behavioral problems in school-age Inuit children.

Am J Orthopsychiatry 2015 May;85(3):250-8

School of Psychology.

A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the United States, the child is adopted at birth and by a close family member; he or she knows who his or her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with nonadopted children. This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 nonadopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the nonadopted children. The adoption status was not related to the teacher's report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se.
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http://dx.doi.org/10.1037/ort0000071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438859PMC
May 2015

Phenotypic and genetic associations between reading comprehension, decoding skills, and ADHD dimensions: evidence from two population-based studies.

J Child Psychol Psychiatry 2015 Oct 12;56(10):1074-82. Epub 2015 Feb 12.

Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.

Background: The phenotypic and genetic associations between decoding skills and ADHD dimensions have been documented but less is known about the association with reading comprehension. The aim of the study is to document the phenotypic and genetic associations between reading comprehension and ADHD dimensions of inattention and hyperactivity/impulsivity in early schooling and compare them to those with decoding skills.

Methods: Data were collected in two population-based samples of twins (Quebec Newborn Twin Study - QNTS) and singletons (Quebec Longitudinal Study of Child Development - QLSCD) totaling ≈ 2300 children. Reading was assessed with normed measures in second or third grade. Teachers assessed ADHD dimensions in kindergarten and first grade.

Results: Both decoding and reading comprehension were correlated with ADHD dimensions in a similar way: associations with inattention remained after controlling for the other ADHD dimension, behavior disorder symptoms and nonverbal abilities, whereas associations with hyperactivity/impulsivity did not. Genetic modeling showed that decoding and comprehension largely shared the same genetic etiology at this age and that their associations with inattention were mostly explained by shared genetic influences.

Conclusion: Both reading comprehension and decoding are uniquely associated with inattention through a shared genetic etiology.
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http://dx.doi.org/10.1111/jcpp.12394DOI Listing
October 2015

Growth in Inuit children exposed to polychlorinated biphenyls and lead during fetal development and childhood.

Environ Res 2014 Oct 18;134:17-23. Epub 2014 Jul 18.

École de psychologie, Université Laval and Centre de recherche du CHU de Québec, Québec City, QC, Canada. Electronic address:

Background: Because of their geographical location and traditional lifestyle, Canadian Inuit children are highly exposed to polychlorinated biphenyls (PCBs) and lead (Pb), environmental contaminants that are thought to affect fetal and child growth. We examined the associations of these exposures with the fetal and postnatal growth of Inuit children.

Methods: We conducted a prospective cohort study among Inuit from Nunavik (Arctic Québec). Mothers were recruited at their first prenatal visit; children (n=290) were evaluated at birth and at 8-14 years of age. Concentrations of PCB 153 and Pb were determined in umbilical cord and child blood. Weight, height and head circumference were measured at birth and during childhood.

Results: Cord blood PCB 153 concentrations were not associated with anthropometric measurements at birth or school age, but child blood PCB 153 concentrations were associated with reduced weight, height and head circumference during childhood. There was no association between cord Pb levels and anthropometric outcomes at birth, but cord blood Pb was related to smaller height and shows a tendency of a smaller head circumference during childhood.

Interpretation: Our results suggest that chronic exposure to PCBs during childhood is negatively associated with skeletal growth and weight, while prenatal Pb exposure is related to reduced growth during childhood. This study is the first to link prenatal Pb exposure to poorer growth in school-age children.
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http://dx.doi.org/10.1016/j.envres.2014.06.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4262554PMC
October 2014

Gene-environment interplay in the link of friends' and nonfriends' behaviors with children's social reticence in a competitive situation.

Dev Psychol 2014 Mar 16;50(3):956-67. Epub 2013 Sep 16.

Department of Psychology, Laval University.

This study used a genetically informed design to assess the effects of friends' and nonfriends' reticent and dominant behaviors on children's observed social reticence in a competitive situation. Potential gene-environment correlations (rGE) and gene-environment interactions (GxE) in the link between (a) friends' and nonfriends' behaviors and (b) children's social reticence were examined. The sample comprised 466 twin children (i.e., the target children), each of whom was assessed in kindergarten together with a same-sex friend and two nonfriend classmates of either sex. Multilevel regression analyses revealed that children with a genetic disposition for social reticence showed more reticent behavior in the competitive situation and were more likely to affiliate with reticent friends (i.e., rGE). Moreover, a higher level of children's reticent behavior was predicted by their friends' higher social reticence (particularly for girls) and their friends' higher social dominance, independently of children's genetic disposition. Children's social reticence was also predicted by their nonfriends' behaviors. Specifically, children were less reticent when male nonfriends showed high levels of social reticence in the competitive situation, and this was particularly true for children with a genetic disposition for social reticence (i.e., GxE). Moreover, children genetically vulnerable for social reticence seemed to foster dominant behavior in their female nonfriend peers (i.e., rGE). In turn, male nonfriends seemed to be more dominant as soon as the target children were reticent, even if the target children did not have a stable genetic disposition for this behavior.
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http://dx.doi.org/10.1037/a0034354DOI Listing
March 2014

Associations between prenatal cigarette smoke exposure and externalized behaviors at school age among Inuit children exposed to environmental contaminants.

Neurotoxicol Teratol 2013 Sep-Oct;39:84-90. Epub 2013 Aug 2.

Université Laval, Québec City, Québec, Canada; Centre de recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada.

Background: Smoking during pregnancy is common among Inuit women from the Canadian Arctic. Yet prenatal cigarette smoke exposure (PCSE) is seen as a major risk factor for childhood behavior problems. Recent data also suggest that co-exposure to neurotoxic environmental contaminants can exacerbate the effects of PCSE on behavior. This study examined the association between PCSE and behavior at school age in a sample of Inuit children from Nunavik, Québec, where co-exposure to environmental contaminants is also an important issue. Interactions with lead (Pb) and mercury (Hg), two contaminants associated with behavioral problems, were also explored.

Methods: Participants were 271 children (mean age=11.3years) involved in a prospective birth-cohort study. PCSE was assessed through maternal recall. Assessment of child behavior was obtained from the child's classroom teacher on the Teacher Report Form (TRF) and the Disruptive Behavior Disorders Rating Scale (DBD). Exposure to contaminants was assessed from umbilical cord and child blood samples. Other confounders were documented by maternal interview.

Results: After control for contaminants and confounders, PCSE was associated with increased externalizing behaviors and attention problems on the TRF and higher prevalence of attention deficit hyperactivity disorder (ADHD) assessed on the DBD. No interactions were found with contaminants.

Interpretation: This study extends the existing empirical evidence linking PCSE to behavioral problems in school-aged children by reporting these effects in a population where tobacco use is normative rather than marginal. Co-exposure to Pb and Hg do not appear to exacerbate tobacco effects, suggesting that these substances act independently.
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http://dx.doi.org/10.1016/j.ntt.2013.07.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812672PMC
November 2014

Genetic and environmental influences on daytime and nighttime sleep duration in early childhood.

Pediatrics 2013 Jun 27;131(6):e1874-80. Epub 2013 May 27.

Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Quebec, Canada.

Objectives: To determine the relative contributions of genetic and environmental factors on daytime and nighttime continuous sleep duration at 6, 18, 30, and 48 months of age, and to identify different subgroups of children who followed different daytime and nighttime sleep duration trajectories and to investigate their etiology.

Methods: The current study included 995 twins (405 monozygotic and 586 dizygotic) of the Quebec Newborn Twin Study recruited from the birth records of the Quebec Statistics Institute. Daytime and nighttime sleep was assessed through maternal reports at 6, 18, 30, and 48 months of age. A semiparametric modeling strategy was used to estimate daytime and nighttime sleep duration trajectories. Quantitative genetic models were used to examine to what extent genetic and environmental factors influenced daytime and nighttime continuous sleep duration.

Results: Genetic modeling analyses revealed environmental influences for all daytime sleep duration trajectories. In contrast, strong genetic influences were found for consolidated nighttime sleep duration (except at 18 months and for the short-increasing sleep duration trajectory).

Conclusions: This is the first indication that early childhood daytime sleep duration may be driven by environmental settings, whereas the variance in consolidated nighttime sleep duration is largely influenced by genetic factors with a critical environmental time-window influence at ∼18 months.
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http://dx.doi.org/10.1542/peds.2012-2284DOI Listing
June 2013

Exposure to organochlorines and mercury through fish and marine mammal consumption: associations with growth and duration of gestation among Inuit newborns.

Environ Int 2013 Apr 17;54:85-91. Epub 2013 Feb 17.

School of Psychology, Laval University and CHUQ Research Center, Quebec, Canada.

Background: Several studies have reported negative associations of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB) and mercury (Hg) with duration of gestation and fetal growth in fish eating populations. Docosahexaenoic acid (DHA) from fish, seafood and marine mammal intake has been reported to be positively related with pregnancy duration and fetal growth. So far, it remains unclear, however, if the associations of environmental contaminants (ECs) with growth are direct or mediated through their relation with the duration of gestation and the degree to which DHA intake during pregnancy attenuates the negative association of ECs with fetal growth.

Objectives: To investigate direct and indirect associations of in utero exposure to ECs with fetal growth and pregnancy duration while taking into account the possible positive effects of DHA.

Methods: Pregnant Inuit women (N=248) from Arctic Quebec were recruited and cord blood samples were analyzed for PCBs, HCB, Hg and DHA. Anthropometric measurements were assessed at birth. Path models were used to evaluate direct and indirect associations.

Results: Cord concentrations of PCB 153, HCB and Hg were significantly associated with shorter duration of pregnancy (β varying from -0.17 to -0.20, p<0.05). Path models indicated that the associations of PCBs, HCB and Hg with reduced fetal growth (β varying from -0.09 to -0.13, p<0.05) were mediated through their relations with shorter gestation duration. Cord DHA was indirectly related to greater growth parameters (β varying from 0.17 to 0.20, p<0.05) through its positive association with gestation duration.

Conclusion: Prenatal exposure to ECs was associated with reduced gestation duration, which is a recognized determinant of fetal growth. DHA intake during pregnancy appeared to have independent positive association with fetal growth by prolonging gestation. Whether these associations are causal remains to be elucidated.
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http://dx.doi.org/10.1016/j.envint.2013.01.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3632409PMC
April 2013

Evidence of gene-environment correlation for peer difficulties: disruptive behaviors predict early peer relation difficulties in school through genetic effects.

Dev Psychopathol 2013 Feb;25(1):79-92

École de Psychologie, Pavillon Félix-Antoine-Savard, 2325 rue des Bibliothèques, Université Laval, Québec, QC G1V 0A6, Canada.

Early disruptive behaviors, such as aggressive and hyperactive behaviors, known to be influenced by genetic factors, have been found to predict early school peer relation difficulties, such as peer rejection and victimization. However, there is no consensus regarding the developmental processes underlying this predictive association. Genetically informative designs, such as twin studies, are well suited for investigating the underlying genetic and environmental etiology of this association. The main goal of the present study was to examine the possible establishment of an emerging gene-environment correlation linking disruptive behaviors to peer relationship difficulties during the first years of school. Participants were drawn from an ongoing longitudinal study of twins who were assessed with respect to their social behaviors and their peer relation difficulties in kindergarten and in Grade 1 through peer nominations measures and teacher ratings. As predicted, disruptive behaviors were concurrently and predictively associated with peer relation difficulties. Multivariate analyses of these associations indicate that they were mainly accounted for by genetic factors. These results emphasize the need to adopt an early and persistent prevention framework targeting both the child and the peer context to alleviate the establishment of a negative coercive process and its consequences.
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http://dx.doi.org/10.1017/S0954579412000910DOI Listing
February 2013

Prenatal methylmercury, postnatal lead exposure, and evidence of attention deficit/hyperactivity disorder among Inuit children in Arctic Québec.

Environ Health Perspect 2012 Oct 21;120(10):1456-61. Epub 2012 Sep 21.

Centre de Recherche du Centre hospitalier universitaire de Québec, Québec, Québec, Canada.

Background: Prenatal exposure to methylmercury (MeHg) and polychlorinated biphenyls (PCBs) has been associated with impaired performance on attention tasks in previous studies, but the extent to which these cognitive deficits translate into behavioral problems in the classroom and attention deficit/hyperactivity disorder (ADHD) remains unknown. By contrast, lead (Pb) exposure in childhood has been associated with ADHD and disruptive behaviors in several studies.

Objectives: In this study we examined the relation of developmental exposure to MeHg, PCBs, and Pb to behavioral problems at school age in Inuit children exposed through their traditional diet.

Methods: In a prospective longitudinal study conducted in the Canadian Arctic, exposure to contaminants was measured at birth and at school age. An assessment of child behavior (n = 279; mean age = 11.3 years) was obtained from the child's classroom teacher on the Teacher Report Form (TRF) from the Child Behavior Checklist, and the Disruptive Behavior Disorders Rating Scale (DBD).

Results: Cord blood mercury concentrations were associated with higher TRF symptom scores for attention problems and DBD scores consistent with ADHD. Current blood Pb concentrations were associated with higher TRF symptom scores for externalizing problems and with symptoms of ADHD (hyperactive-impulsive type) based on the DBD.

Conclusions: To our knowledge, this study is the first to identify an association between prenatal MeHg and ADHD symptomatology in childhood and the first to replicate previously reported associations between low-level childhood Pb exposure and ADHD in a population exposed to Pb primarily from dietary sources.
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http://dx.doi.org/10.1289/ehp.1204976DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3491943PMC
October 2012

Contribution of temporal processing skills to reading comprehension in 8-year-olds: evidence for a mediation effect of phonological awareness.

Child Dev 2012 Jul-Aug;83(4):1332-46. Epub 2012 May 16.

Groupe de recherche sur l’inadaptationpsychosociale chez l’enfant, Université Laval, Québec, QC, Canada.

This study tested whether the association between temporal processing (TP) and reading is mediated by phonological awareness (PA) in a normative sample of 615 eight-year-olds. TP was measured with auditory and bimodal (visual-auditory) temporal order judgment tasks and PA with a phoneme deletion task. PA partially mediated the association between both auditory and bimodal TP and reading, above nonverbal abilities, vocabulary, and processing speed. PA explained a larger proportion of the association between auditory TP and reading (56% vs. 39% for bimodal TP), and most of the association between bimodal TP and reading was direct. This finding is consistent with a dual-phonological and visual-pathway model of the association between TP and reading in normative reading skills.
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http://dx.doi.org/10.1111/j.1467-8624.2012.01777.xDOI Listing
October 2012

Associations of mother's and father's parenting practices with children's observed social reticence in a competitive situation: a monozygotic twin difference study.

J Abnorm Child Psychol 2012 Apr;40(3):391-402

Department of Psychology, University of Quebec at Montreal, C.P. 8888 succursale Centre-ville, Montreal, Quebec, Canada, H3C 3P8.

This study used the monozygotic (MZ) twin difference method to examine whether the unique environmental effects of maternal and paternal overprotection and hostility at the age of 30 months predict twins' observed social reticence in a competitive situation in kindergarten, while controlling for the effect of family-wide influences, including genetic and shared environmental factors, family socio-economical status and twin's birth weight. It was also examined whether these associations are moderated by parental depressive symptoms. Participants were 137 MZ twin pairs who were part of an ongoing longitudinal study. Hierarchical linear regressions revealed that differences in maternal and paternal overprotection predicted differences in twins' social reticence, albeit only in boys. Differences in paternal hostile parenting predicted differences in girls' reticent behavior, but only when fathers showed high levels of depressive symptoms. Hence, overprotected boys, as well as girls confronted with father's hostility and depressive symptoms, may tend to withdraw rather than face the challenge when experiencing difficult social situations such as competition. The results from the present study suggest that targeting maladaptive maternal as well as paternal child-rearing practices and psychopathology early on may be useful for reducing later internalizing behavior in the offspring.
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http://dx.doi.org/10.1007/s10802-011-9573-8DOI Listing
April 2012

Associations between sleep-wake consolidation and language development in early childhood: a longitudinal twin study.

Sleep 2011 Aug 1;34(8):987-95. Epub 2011 Aug 1.

Research Unit on Children’s Psychosocial Maladjustment, Montreal, Canada.

Study Objectives: The objectives were (1) to assess associations between sleep consolidation at 6, 18 and 30 months and language skills at 18, 30, and 60 months; and (2) to investigate the genetic/environmental etiology of these associations.

Design: Longitudinal study of a population-based twin cohort.

Participants: 1029 twins from the Quebec Newborn Twin Study.

Measurements And Results: Sleep consolidation was derived from parental reports of day/night consecutive sleeping durations. Language skills were assessed with the MacArthur Communicative Development Inventory at 18 and 30 months and the Peabody Picture Vocabulary Test at 60 months. The day/night sleep ratio decreased significantly from 6 to 30 months. The 6- and 18-month ratios were negatively correlated with subsequent language skills. Children with language delays at 60 months had less mature sleep consolidation at both 6 and 18 months than children without delays and those with transient early delays. Genetic and regression analyses revealed that the sleep ratio at 6 months was highly heritable (64%) and predicted 18-month (B = -0.06) and 30-month language (B = -0.11) mainly through additive genetic influences (R(Gs) = 0.32 and 0.33, respectively). By contrast, the sleep ratio at 18 months was mainly due to shared environment influences (58%) and predicted 60-month language (B = -0.08) through shared environment influences (R(Cs) = 0.24).

Conclusions: Poor sleep consolidation during the first 2 years of life may be a risk factor for language learning, whereas good sleep consolidation may foster language learning through successive genetic and environmental influences.
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http://dx.doi.org/10.5665/SLEEP.1148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3138173PMC
August 2011

Heritability of response inhibition in children.

J Int Neuropsychol Soc 2011 Mar 21;17(2):238-47. Epub 2010 Dec 21.

Neurosciences and Mental Health Programme, Research Institute and the Department of Psychiatry, The Hospital for Sick Children & University of Toronto, Toronto, Canada.

We report the heritability of response inhibition, latency, and variability, which are potential markers of genetic risk in neuropsychiatric conditions. Genetic and environmental influences on cancellation and restraint, response latency, and variability measured in a novel variant of the stop signal task were studied in 139 eight-year-old twin pairs from a birth cohort. Cancellation (50%), restraint (27%), and response latency (41%) showed significant heritability, the balance being non-shared environmental influences and/or error. Response variability was not heritable, with 23% of the variance attributable to shared environmental influences and 77% to non-shared environmental risk or error. The phenotypic correlation between response cancellation and restraint was -.44 and between response latency and restraint was .21. These phenotypic correlations were entirely genetic in origin. The phenotypic correlation between response variability and % successful inhibition was .27, but was not genetic. Cancellation and restraint were heritable and shared genetic influences, indicating that they may be influenced by a common gene or genes. Response latency was moderately heritable and shared genetic influences with restraint, but was not correlated with cancellation. Response variability was not heritable. These results support the potential of response inhibition and latency as endophenotypes in genetic research.
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http://dx.doi.org/10.1017/S1355617710001463DOI Listing
March 2011

De novo truncating mutation in Kinesin 17 associated with schizophrenia.

Biol Psychiatry 2010 Oct 19;68(7):649-56. Epub 2010 Jun 19.

Department of Medicine, Center of Excellence in Neuromics of Université de Montréal, Centre Hospitalier de l'Université de Montreal Research Center, University of Montréal, Montreal, Quebec, Canada.

Background: Schizophrenia (SCZ) is one of the most disabling psychiatric disorders. It is thought to be due to a complex interplay between polygenic and various environmental risk factors, although recent reports on genomic copy number variations suggest that a fraction of the cases could result from variably penetrant de novo variants. The gene encoding the synaptic motor protein kinesin 17 (KIF17) involved in glutamatergic synapse is a candidate gene for SCZ.

Methods: As part of our Synapse to Disease project, we resequenced KIF17 in a cohort of individuals with sporadic SCZ (188 subjects). Additional populations included autism spectrum disorder (142 subjects), nonsyndromic mental retardation (95 subjects), and control subjects (568 subjects). Functional validation of the human mutation was done in developing zebrafish.

Results: Here we report the identification of a de novo nonsense truncating mutation in one patient with SCZ, in kinesin 17, a synaptic motor protein. No de novo or truncating KIF17 mutations were found in the additional samples. We further validated the pathogenic nature of this mutation by knocking down its expression in zebrafish embryos, which resulted in a developmental defect.

Conclusions: Together our findings suggest that disruption of KIF17, although rare, could result in a schizophrenia phenotype and emphasize the possible involvement of rare de novo mutations in this disorder.
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http://dx.doi.org/10.1016/j.biopsych.2010.04.018DOI Listing
October 2010

Maternal self-efficacy and hostile-reactive parenting from infancy to toddlerhood.

Infant Behav Dev 2010 Apr;33(2):149-58

Laval University, Québec, Canada G1V 0A6.

A longitudinal study of maternal self-efficacy (SE) and hostile-reactive parenting (HRP) was conducted with a community sample of 1836 mothers. Mothers completed questionnaires when their child was 4.5, 16.6 and 28.5 months of age. Maternal SE showed little change, whereas HRP sharply increased from 4.5 to 28.5 months. Structural equation models suggest these initially correlated variables did not influence each other over time, but rather became increasingly independent. Three distinct developmental trajectories were fitted for both maternal SE and HRP. In contrast to the overall portrait of stability, 12.6% of mothers followed a trajectory of declining SE. Likewise, 12.1% of mothers showed initially high and sharply increasing HRP. Few mothers (3.1%) simultaneously followed both of these trajectories, yet overall, SE and HRP trajectories were modestly associated (tau(b)=-.23, p<.0001). Failure to support the expected reciprocal influences between SE and HRP over time, as well as maternal and child contributions to early manifestations of maternal HRP and their evolution are discussed.
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http://dx.doi.org/10.1016/j.infbeh.2009.12.005DOI Listing
April 2010

Early child language mediates the relation between home environment and school readiness.

Child Dev 2009 May-Jun;80(3):736-49

Université Laval, Quebec City, QC G1V 0A6, Canada.

Home environment quality is a well-known predictor of school readiness (SR), although the underlying processes are little known. This study tested two hypotheses: (a) child language mediates the association between home characteristics (socioeconomic status and exposure to reading) and SR, and (b) genetic factors partly explain the association between language and SR. Data were collected between 6 and 63 months in a large sample of twins. Results showed that home characteristics had direct effects on SR and indirect effects through child language. No genetic correlation was found between language and SR. These results suggest that home characteristics affect SR in part through their effect on early language skills, and show that this process is mainly environmental rather than genetic in nature.
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http://dx.doi.org/10.1111/j.1467-8624.2009.01294.xDOI Listing
October 2009

The genetic-environmental etiology of cognitive school readiness and later academic achievement in early childhood.

Child Dev 2007 Nov-Dec;78(6):1855-69

Groupe de recherche sur l'inadaptation psychosociale chez l'enfant, Ecole de psychologie, Université Laval, Québec G1K 7P4, Canada.

Using a genetic design of 840 60-month-old twins, this study investigated the genetic and environmental contributions to (a) individual differences in four components of cognitive school readiness, (b) the general ability underlying these four components, and (c) the predictive association between school readiness and school achievement. Results revealed that the contribution of the shared environment for cognitive school readiness was substantial. Genetic effects were more important for the core abilities underlying school readiness than for each specific skill, although shared environment remained the largest factor overall. Genetic, shared, and nonshared environmental factors all accounted for the predictive association between school readiness and early school achievement. These results contribute to a better understanding of the early determinants of school readiness.
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http://dx.doi.org/10.1111/j.1467-8624.2007.01103.xDOI Listing
February 2008

A longitudinal twin study of the genetic and environmental etiology of maternal hostile-reactive behavior during infancy and toddlerhood.

Infant Behav Dev 2007 Aug 12;30(3):453-65. Epub 2007 Jan 12.

Groupe de Recherche sur l'Inadaptation Psychosociale Chez l'Enfant, Université Laval, Québec, Canada.

Children's negative characteristics are thought to be a factor in evoking hostile parenting responses. This can result in genotype/environment correlations (rGE) in which children's heritable traits influence the parenting they experience. We did genetic analyses on 292 mothers' self-reported hostile-reactive behaviors toward each of their twins at 5, 18 and 30 months. Finding heritability for a parenting behavior analyzed as a child phenotype is evidence of rGE correlation. The heritability of maternal behavior was modest (29% at 5 months, 0% at 18 months, and 25% at 30 months) and longitudinal analyses indicated that genetic factors at 5 and 30 months were uncorrelated. Common environment factors, probably reflecting characteristics of the mothers, were the main source of variance at the three ages and were highly correlated through time. We concluded that children's heritable characteristics evoked maternal negative response at specific times, but were not responsible for the stability of maternal hostility from infancy to toddlerhood.
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http://dx.doi.org/10.1016/j.infbeh.2006.12.005DOI Listing
August 2007