142 research outputs found
Le rÎle de la garde non-maternelle sur le développement cognitif et la sécrétion cortisolaire des enfants : investigations longitudinales populationnelles et méta-analytiques
Résumé
La présente thÚse doctorale vise à déterminer sous quelles conditions la garde non-maternelle est associée (positivement/négativement) au niveau de stress et au développement cognitif des enfants. Elle comporte une recension des écrits et trois articles empiriques.
Le premier article prĂ©sente une recension des Ă©crits (de type mĂ©ta-analytique) qui synthĂ©tise les Ă©tudes portant sur le stress des enfants en services de garde et ayant utilisĂ© le niveau de cortisol comme indicateur. Les rĂ©sultats montrent que la garde non-maternelle est associĂ©e au niveau de stress des enfants, se reflĂ©tant dans des concentrations de cortisol Ă©levĂ©es. Les niveaux de stress Ă©levĂ©s sâobservent particuliĂšrement chez les enfants qui au dĂ©part ont tendance Ă ĂȘtre retirĂ©s, anxieux ou qui sont gardĂ©s dans un milieu de faible qualitĂ©. Cependant, certains Ă©lĂ©ments indiquent que les Ă©lĂ©vations de cortisol Ă la garderie sont temporaires et quâelles disparaissent au fur et Ă mesure que lâenfant sâadapte Ă son milieu.
Le deuxiĂšme article de thĂšse, rĂ©alisĂ© dans le contexte de lâĂchantillon longitudinal national des enfants et des jeunes [ELNEJ] (n = 3093), vise Ă dĂ©terminer dans quelle mesure lâassociation entre la frĂ©quentation des services de garde et lâacquisition du vocabulaire rĂ©ceptif au prĂ©scolaire dĂ©pend du milieu familial de lâenfant. Les rĂ©sultats indiquent quâĂ lâintĂ©rieur du groupe dâenfants dĂ©favorisĂ©s, ceux ayant Ă©tĂ© gardĂ©s Ă temps plein dans la premiĂšre annĂ©e de vie obtiennent des scores supĂ©rieurs sur une mesure de vocabulaire rĂ©ceptif administrĂ©e Ă 4 Âœ ans, comparativement aux enfants restĂ©s Ă la maison avec la mĂšre (d=0.58).
Le troisiĂšme article, rĂ©alisĂ© dans le contexte de lâĂtude longitudinale des enfants du QuĂ©bec [ELDEQ]; (n=2,120), vise Ă documenter les bĂ©nĂ©fices Ă long terme de la frĂ©quentation des services de garde par les enfants issus de milieux dĂ©savantagĂ©s sur la prĂ©paration scolaire et les compĂ©tences acadĂ©miques. Les rĂ©sultats rĂ©vĂšlent que les enfants dont la mĂšre nâa pas terminĂ© ses Ă©tudes secondaires obtiennent de meilleurs rĂ©sultats sur une mesure de prĂ©paration scolaire cognitive (d=0.56) et de vocabulaire rĂ©ceptif (d=0.30) en maternelle, et de connaissance des nombres (d=0.43) en premiĂšre annĂ©e, sâils ont frĂ©quentĂ© un service de garde sur une base rĂ©guliĂšre. Par ailleurs, la garde non-parentale nâest pas associĂ©e aux compĂ©tences cognitives des enfants de milieux sociaux favorisĂ©s.
Lâobjectif du quatriĂšme article est dâexaminer les facteurs de sĂ©lection quant Ă lâutilisation des services de garde dans le contexte de lâELDEQ. Les rĂ©sultats montrent que lâabsence dâemploi de la mĂšre pendant la grossesse, le faible niveau dâĂ©ducation de la mĂšre; le revenu insuffisant de la famille, avoir plus de 2 frĂšres et sĆurs, la surprotection maternelle, et le faible niveau de stimulation cognitive sont associĂ©s Ă une faible utilisation des services de garde (30.7% de lâĂ©chantillon quĂ©bĂ©cois).
En dâautres termes, les enfants qui sont les plus susceptibles de retirer des avantages des services de garde sur le plan du dĂ©veloppement, en raison de la prĂ©sence de facteurs de risque dans leur milieu familial, sont aussi ceux qui utilisent le moins les services de garde.Abstract
The present doctoral thesis aims at determining under which conditions child-care experiences may be associated (positively or negatively) with childrenâs stress levels and cognitive development. It comprises one literature review and three empirical studies.
The first study is a literature review (meta-analysis type) which summarizes the studies on child-care experiences and childrenâs stress (as indexed by cortisol) in order to identify individual and environmental conditions under which child-care is associated with elevated cortisol concentrations. Findings suggest that child-care may be more stressful, as reflected in higher salivary cortisol concentrations, for children who are less socially competent or who received low quality child-care services. However, some pieces of evidence suggest that cortisol elevations in child-care are transient and fade out as children grow older
The second study uses data from the National Longitudinal Survey of Children and Youth [NLSCY]; (n=3093). The goal is to determine whether the association between non-maternal care and receptive vocabulary skills depend upon childrenâs home environment. Results show that children from low socioeconomic status who received full-time (< 25 hours/week) child-care services in their first year of life obtain higher scores on a measure of receptive vocabulary at 4 Âœ years than those who were cared for by their mothers (d=0.58).
The goal of the third study is to document further the longer-term benefits of early child-care attendance on disadvantaged childrenâs school readiness and school achievement. This study uses data from the Quebec Longitudinal Study of Child Development [QLSCD]; (n=2120). Findings reveal that child-care services produce benefits over maternal care for children from low educated mothers on a measure of receptive vocabulary (d=0.30) and cognitive school readiness (d=0.56) in kindergarten, and number knowledge in first grade (d=0.43). Overall, child-care services produce no advantage or disadvantage for children who do not experience risks in their home.
The objective of the fourth study is to identify key family factors associated with low child-care services utilization, using the QLSCD sample. Results show that maternal unemployment during pregnancy, low levels of maternal education; insufficient household income, having more than two siblings, high levels of maternal overprotection, and low levels of cognitive stimulation are associated with lower child-care services use (30.7% of the Quebec sample).
In sum, children who are the most likely to benefit from child-care services in terms of their development are also those who are less likely to receive it
SPS-prepared targets for sputtering deposition of phase change films.
Phase-change materials like thin films from the systems [Ge1-xPbx]Te and Ge[Te1-xSex] are of interest for data storage. For these compositions amorphous materials can not be obtained by melt quenching. However, Suitable films can be obtained using RF sputtering. Spark plasma sintering (SPS) was used to densify the powders to obtain large targets. Synthesis conditions and characterisations of the targets are reported. Amorphous nano films were obtained using the sintered targets and characterised
Time Series Forecasting: Obtaining Long Term Trends with Self-Organizing Maps
à la suite de la conférence ANNPR, Florence 2003International audienceKohonen self-organisation maps are a well know classification tool, commonly used in a wide variety of problems, but with limited applications in time series forecasting context. In this paper, we propose a forecasting method specifically designed for multi-dimensional long-term trends prediction, with a double application of the Kohonen algorithm. Practical applications of the method are also presented
Association of childhood bullying victimisation with suicide deaths: findings from a 50-year nationwide cohort study
BACKGROUND: Bullying victimisation has been associated with increased risk of suicide ideation and attempt throughout the lifespan, but no study has yet examined whether it translates to a greater risk of death by suicide. We aimed to determine the association of bullying victimisation with suicide mortality.
METHODS: Participants were drawn from the 1958 British birth cohort, a prospective follow-up of all births in 1 week in Britain in 1958. We conducted logistic regressions on 14 946 participants whose mothers reported bullying victimisation at 7 and 11 years with linked information on suicide deaths through the National Health Service Central Register.
RESULTS: Fifty-five participants (48 males) had died by suicide between the age 18 and 52 years. Bullying victimisation was associated with suicide mortality; a one standard deviation increases in bullying victimisation linked to an increased odds for suicide mortality [odds ratio (OR) 1.29; 1.02-1.64] during adulthood. The OR attenuated by 11% after adjustment for individual (e.g. behavioural and emotional problems) and familial characteristics (e.g. adverse childhood experiences, 1.18; 0.92-1.51). Analysis of bullying victimisation frequency categories yields similar results: compared with individuals who had not been bullied, those who had been frequently bullied had an increased odds for suicide mortality (OR 1.89; 0.99-3.62).
CONCLUSION: Our study suggests that individuals who have been frequently bullied have a small increased risk of dying by suicide, when no other risk factors is considered. Suicide prevention might start in childhood, with bullying included in a range of inter-correlated vulnerabilities encompassing behavioural and emotional difficulties and adverse experiences within the family
Child care services, socioeconomic inequalities, and academic performance
Objective. To determine if child care services (CCS) at a population level can reduce social
inequalities in academic performance until early adolescence.
Method. A 12-year population-based prospective cohort study of families with a newborn (n =
1269). Two CCS variables were estimated: âintensityâ (low, moderate and high number of hours)
and âCenter-Based CCS Typeâ (early-, late-onset, and never exposed to center-based CCS).
Results. Children from low socioeconomic status (SES) families who received high-intensity
CCS (any type), compared to those who received low-intensity CCS, had significantly better
reading (Standardized Effect Size [ES]= .37), writing (ES=.37), and mathematics (ES=.46)
scores. Children from low-SES families who received center-based CCS, compared to those who
never attended center-care, had significantly better reading (ES early-onset =.68; ES late-onset =.37),
writing (ES early-onset =.79), and mathematics (ES early-onset =.66; ES late-onset =.39) scores.
Furthermore, early participation in center-based CCS eliminated the differences between
children of low- and adequate-SES on all three exams (ES = -.01, .13, and -.02 for reading,
writing and mathematics, respectively). These results were obtained while controlling for a wide
range of child and family variables from birth to school entry.
Conclusion. Child care services (any type) can reduce the social inequalities in academic
performance up to early adolescence, while early participation in center-based CCS can
eliminate this inequality. CCS use, especially early participation in center-based CCS should be
strongly encouraged for children growing up in a low-SES family
Are early-life antecedents of suicide mortality associated with psychiatric disorders and suicidal ideation in midlife?
Objective: To establish whether previously identified earlyâlife antecedents of suicide mortality (i.e. low birthweight, younger maternal age, higher birth order, externalizing problems and adversities) are associated with proximal psychiatric disorders and suicidal ideation, which are themselves associated with an increased risk of suicide. / Methods: Participants were from the 1958 British birthâcohort (N = 8905) with information on prenatal/childhood experiences and the Clinical Interview ScheduleâRevised at age 45 years. Outcomes were as follows: any internalizing disorder (anxiety disorder/depressive episode), depressive episode, alcohol use disorder and suicidal ideation. / Results: After adjustment, higher birth order (Ptrend = 0.043), younger maternal age (Ptrend = 0.017) and increased number of childhood adversities (Ptrend = 0.026) were associated with an increased risk of internalizing disorders. For example, the OR (95% CI) in fourthâ or laterâborn children was 1.48 (1.06â2.07) and for young maternal age (<19 years) was 1.31 (0.89â1.91). Effect sizes were similar in magnitude for depressive episode and suicidal ideation, although associations did not reach conventional significance levels. No associations were found for low birthweight and externalizing problems (in males) and investigated outcomes. / Conclusion: Associations for younger maternal age, higher birth order and adversities with adult internalizing disorders suggest that psychiatric disorders may be on the pathway linking some earlyâlife factors and suicide
Childhood cognitive skills trajectories and suicide by mid-adulthood:an investigation of the 1958 British Birth Cohort
International audienceBackground : Poor cognitive abilities and low intellectual quotient (IQ) are associated with an increased risk of suicide attempts and suicide mortality. However, knowledge of how this association develops across the life-course is limited. Our study aims to establish whether individuals who died by suicide by mid-adulthood are distinguishable by their child-to-adolescence cognitive trajectories.Methods : Participants were from the 1958 British Birth Cohort and were assessed for academic performance at ages 7, 11, and 16 and intelligence at 11 years. Suicides occurring by September 2012 were identified from linked national death certificates. We compared mean mathematics and reading abilities and rate of change across 7â16 years for individuals who died by suicide v. those still alive, with and without adjustment for potential early-life confounding factors. Analyses were based on 14 505 participants.Results : Fifty-five participants (48 males) had died by suicide by age 54 years. While males who died by suicide did not differ from participants still alive in reading scores at age 7 [effect size (g) = â0.04, p = 0.759], their reading scores had a less steep improvement up to age 16 compared to other participants. Adjustments for early-life confounding factors explained these differences. A similar pattern was observed for mathematics scores. There was no difference between individuals who died by suicide v. participants still alive on intelligence at 11 years.Conclusions : While no differences in tests of academic performance and IQ were observed, individuals who died by suicide had a less steep improvement in reading abilities over time compared to same-age peers
Early childhood factors associated with peer victimization trajectories from 6 to 17 years of age
OBJECTIVES:
To describe (1) the developmental trajectories of peer victimization from 6 to 17 years of age and (2) the early childhood behaviors and family characteristics associated with the trajectories.
METHODS:
We used data from 1760 children enrolled in the Quebec Longitudinal Study of Child Development, a population-based birth cohort. Participants self-reported peer victimization at ages 6, 7, 8, 10, 12, 13, 15, and 17 years. Participantsâ behavior and family characteristics were measured repeatedly between ages 5 months and 5 years.
RESULTS:
We identified 4 trajectories of peer victimization from 6 to 17 years of age: low (32.9%), moderate-emerging (29.8%), childhood-limited (26.2%), and high-chronic (11.1%). Compared with children in the low peer victimization trajectory, children in the other 3 trajectories were more likely to exhibit externalizing behaviors in early childhood, and those in the high-chronic and moderate-emerging trajectories were more likely to be male. Paternal history of antisocial behavior was associated with moderate-emerging (odds ratio [OR] = 1.54; 95% confidence interval [CI] = 1.09â2.19) and high-chronic (OR = 1.93; 95% CI = 1.25â2.99) relative to low peer victimization. Living in a nonintact family in early childhood was associated with childhood-limited (OR = 1.48; 95% CI = 1.11â1.97) and high-chronic (OR = 1.59; 95% CI = 1.09â2.31) relative to low peer victimization.
CONCLUSIONS:
Early childhood externalizing behaviors and family vulnerabilities were associated with the development of peer victimization. Some children entered the cascade of persistent peer victimization at the beginning of primary school. Support to these children and their families early in life should be an important component of peer victimization preventive interventions
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