Richard E Tremblay

Université de Montréal, Montréal, Quebec, Canada

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Publications (450)1509.84 Total impact

  • Linda Booij, Richard E Tremblay, Moshe Szyf, Chawki Benkelfat
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    ABSTRACT: Despite more than 60 years of research in the role of serotonin (5-HT) in psychopathology, many questions still remain. From a developmental perspective, studies have provided more insight into how 5-HT dysfunctions acquired in utero or early in life may modulate brain development. This paper discusses the relevance of the developmental role of 5-HT for the understanding of psychopathology. We review developmental milestones of the 5-HT system, how genetic and environmental 5-HT disturbances could affect brain development and the potential role of DNA methylation in 5-HT genes for brain development.
    Journal of psychiatry & neuroscience: JPN 10/2014; 39(5):140099. · 6.24 Impact Factor
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    ABSTRACT: DNA methylation patterns are characterized by highly conserved developmental programs, but allow for divergent gene expression resulting from stochastic epigenetic drift or divergent environments. Genome-wide methylation studies in monozygotic (MZ) twins are providing insight into the extent of epigenetic variation that occurs, irrespective of genotype. However, little is known about the variability of DNA methylation patterns in adolescence, a period involving significant and rapid physical, emotional, social, and neurodevelopmental change. Here, we assessed genome-wide DNA methylation using the 450 K Illumina BeadChip in a sample of 37 MZ twin pairs followed longitudinally since birth to investigate: 1) the extent of variation in DNA methylation in identical genetic backgrounds in adolescence and; 2) whether these variations are randomly distributed or enriched in particular functional pathways. We also assessed stability of DNA methylation over 3-6 months to distinguish stable trait-like and variable state-like genes. A pathway analysis found high within-pair variability in genes associated with development, cellular mechanisms, tissue and cell morphology, and various disorders. Test-retest analyses performed in a sub-sample of 8 twin pairs demonstrated enrichment in gene pathways involved in organismal development, cellular growth and proliferation, cell signaling, and particular disorders. The variability found in functional gene pathways may plausibly underlie phenotypic differences in this adolescent MZ twin sample. Furthermore, we assessed stability of methylation over 3-6 months and found that some genes were stable while others were unstable, suggesting that the methylome remains dynamic in adolescence and that dynamic sites tend to be organized in certain gene pathways.
    Epigenetics: official journal of the DNA Methylation Society 10/2014; 9(10):1410-22. · 4.58 Impact Factor
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    ABSTRACT: Background Little is known about the associations between self-reported offending and official offending whilst considering different types of offences.AimsThe aims of the present study are to identify developmental trajectories of self-reported violent and nonviolent offending (SRVO; SRNVO) and to examine their associations with official violent and nonviolent offences (as juveniles and adults).Methods Developmental trajectories of SRVO and SRNVO from 11 to 17 years of age were estimated with data from the Montreal Longitudinal and Experimental Study, a prospective longitudinal study of 1037 boys from disadvantaged neighbourhoods.ResultsFive trajectories of SRVO (i.e. Chronic, Desisting, Delayed, Moderate and Low) and three trajectories of SRNVO (Chronic, Moderate and Low) were identified. Chronic, Desisting and Delayed trajectories of SRVO were associated with violent and nonviolent official offending in adolescence and early adulthood, over and above the trajectories of SRNVO. In comparison, trajectories of SRNVO were weakly and inconsistently associated with official offending, once controlling for their overlap with trajectories of SRVO.Conclusions Individuals on high trajectories of violent offending during adolescence are most at risk for being exposed to the justice system both concurrently and longitudinally. Differentiating violent and nonviolent offending can help resolve part of the discordance between self-reported and official offending. Copyright © 2014 John Wiley & Sons, Ltd.
    Criminal Behaviour and Mental Health 10/2014; 24(4). · 1.28 Impact Factor
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    ABSTRACT: Proactive aggression (PA) describes an instrumental behavior that is goal-oriented, whereas reactive aggression (RA) refers to an angry or frustrated aggressive response to a real or perceived threat. Little is known about the respective roles of genetic (G) and environmental (E) factors associated with PA and RA during childhood. The objectives of this study were to investigate a) the G-E etiology of the commonality between PA and RA and b) the presence of G or E components specific to PA or RA throughout childhood (i.e., from 6 to 12 years of age). Participants were 254 monozygotic and 413 dizygotic pairs. Teacher reports of PA and RAwere obtained at 6, 7, 9, 10 and 12 years of age. Throughout childhood, genetic factors accounted for most of the common variance between PAand RA, as well as their specificity. Shared environment played no role. Specifically, genetic factors common to PA and RA explained between 39% and 45% of the variance in PA, and between 27% and 42% of the variance in RA. Genetic factor also uniquely accounted for only but a small percentage (9% at 6 years and 3% at 9 years old) of the variation in PA. As for RA, three distinctive genetic factors contributed to phenotypic variation throughout childhood and explained between 12% and 22% of variance. Dynamic genetic factors accounted for the commonality in PA and RA, and for the specificity of RA. Few genetic factors were unique to PA; in contrast, for RA, an early, specific and persistent genetic factor was found alongside new genetic factors that appeared at later ages. These results challenge theoretical models that focus primarily on the effects of environmental factors in the etiology of reactive and proactive aggression.
    Monatsschrift fûr Kriminologie und Strafrechtsreform. 10/2014; 97.
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    ABSTRACT: Background The impact of longitudinal psychiatric comorbidity, parenting and social characteristics on attention-deficit hyperactivity disorder (ADHD) medication use is still poorly understood. Aims To assess the baseline and longitudinal influences of behavioural and environmental factors on ADHD medication use. Method Survival regressions with time-dependent covariates were used to model data from a population-based longitudinal birth cohort. The sample (n = 1920) was assessed from age 5 months to 10 years. Measures of children's psychiatric symptoms, parenting practices and social characteristics available at baseline and during follow-up were used to identify individual and family-level features associated with subsequent use of ADHD medication. Results Use of ADHD medication ranged from 0.2 to 8.6% between ages 3.5 to 10 years. Hyperactivity-inattention was the strongest predictor of medication use (hazard ratio (HR) = 2.75, 95% CI 2.35-3.22). Among all social variables examined, low maternal education increased the likelihood of medication use (HR = 2.09, 95% CI 1.38-3.18) whereas immigrant status lowered this likelihood (HR = 0.40, 95% CI 0.17-0.92). Conclusions Beyond ADHD symptoms, the likelihood of receiving ADHD medication is predicted by social variables and not by psychiatric comorbidity or by parenting. This emphasises the need to improve global interventions by offering the same therapeutic opportunities (including medication) as those received by the rest of the population to some subgroups (i.e. immigrants) and by diminishing possible unnecessary prescriptions.
    The British journal of psychiatry: the journal of mental science 08/2014; · 6.62 Impact Factor
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    ABSTRACT: Heart rate variability (HRV) is a non-invasive quantitative marker of cardiac autonomic function derived from continuous electrocardiogram (ECG) recordings. Normative HRV values and development factors have not been established in pediatric populations. The objective was to derive referent time- and frequency-domain HRV values for a population-based sample of children. Children aged 9-11 years (N = 1,036) participated in the Québec Longitudinal Study of Child Development cohort cardiovascular health screening. Registered nurses measured anthropometrics (height, weight) and children wore an ambulatory Holter monitor to continuously record an ECG signal. HRV variables included time (SDNN, pNN50, RMSSD, SDANN) and frequency (HF, LF, LF/HF ratio) domain variables. Normative HRV values, stratified by age, sex, and heart rate, are presented. Greater heart rate (β avg = -0.60, R avg (2) = 0.39), pubertal maturation (β avg = -0.11, R avg (2) = 0.01), later ECG recording times (β avg = -0.19, R avg (2) = 0.07), and higher diastolic blood pressure (β avg = -0.11, R avg (2) = 0.01) were significantly associated with reduced HRV in 10-year-old children. The normative HRV values permit clinicians to monitor, describe, and establish pediatric nosologies in primary care and research settings, which may improve treatment of diseases associated with HRV in children. By better understanding existing values, the practical applicability of HRV among clinicians will be enhanced. Lastly, developmental (e.g., puberty) and procedural (e.g., recording time) factors were identified that will improve recording procedures and interpretation of results.
    Pediatric cardiology. 07/2014;
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    ABSTRACT: In this 16-year longitudinal study, a new trajectory estimation approach was used to verify whether the developmental course of childhood inattention significantly predicted functional impairment. A rising childhood inattention trajectory significantly predicted graduation failure (OR: 1.76 [1.32-2.34]) independently of averaged inattention levels. Rising inattention is, in itself, important for prognosis.
    Psychiatry Research 06/2014; · 2.68 Impact Factor
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    ABSTRACT: Background Research on associations between children's prosocial behaviour and mental health has provided mixed evidence. The present study sought to describe and predict the joint development of prosocial behaviour with externalizing and internalizing problems (physical aggression, anxiety and depression) from 2 to 11 years of age.Method Data were drawn from the National Longitudinal Survey of Children and Youth (NLSCY). Biennial prosocial behaviour, physical aggression, anxiety and depression maternal ratings were sought for 10,700 children aged 0 to 9 years at the first assessment point.ResultsWhile a negative association was observed between prosociality and physical aggression, more complex associations emerged with internalizing problems. Being a boy decreased the likelihood of membership in the high prosocial trajectory. Maternal depression increased the likelihood of moderate aggression, but also of joint high prosociality/low aggression. Low family income predicted the joint development of high prosociality with high physical aggression and high depression.Conclusions Individual differences exist in the association of prosocial behaviour with mental health. While high prosociality tends to co-occur with low levels of mental health problems, high prosociality and internalizing/externalizing problems can co-occur in subgroups of children. Child, mother and family characteristics are predictive of individual differences in prosocial behaviour and mental health development. Mechanisms underlying these associations warrant future investigations.
    Journal of Child Psychology and Psychiatry 04/2014; · 5.42 Impact Factor
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    ABSTRACT: Several authors consider high and frequent conflicts between friends during childhood as a serious risk for subsequent conduct problems such as generalized physical aggression toward others (e.g., Kupersmidt, Burchinal, & Patterson, 1995; Sebanc, 2003). Although it seems logical to assume that friendship conflict could have some negative consequences on children's behaviors, some scholars have suggested that a certain amount of conflict between friends may actually promote social adjustment (e.g., Laursen & Pursell, 2009). The aim of this study was to investigate the role of friendship conflict in regard to the development of generalized physical aggression toward others in the early school years (i.e., from kindergarten to Grade 1), as well as the moderating role of relational (i.e., shared positive affect and dyadic conflict resolution skills) and personal (i.e., children's sex and genetic liability for aggression) characteristics in this context. The sample included 745 twins assessed through teacher, peer, child, and friend ratings in kindergarten and Grade 1. Friendship conflict in kindergarten was linearly related to an increase in boys' but not girls' generalized physical aggression. However, shared positive affect and conflict resolution skills mitigated the prospective associations between friendship conflict and generalized physical aggression. These results were independent of children's sex, genetic risk for physical aggression, and initial levels of generalized physical aggression in kindergarten. Fostering a positive relationship between friends at school entry may buffer against the risk associated with experiencing friendship conflict. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
    Developmental Psychology 03/2014; · 3.21 Impact Factor
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    ABSTRACT: Little empirical evidence exists on the comparability of heart rate variability (HRV) quantification methods commonly used in infants. The aim was to compare three methods of HRV estimation: (1) fast Fourier transform (FFT), (2) autoregressive (AR), and (3) the Porges methods. HRV was estimated in 63 healthy 5-month-old infants. HRV parameters were strongly correlated across methods (.92-.99) but yielded significantly different mean HRV estimates (Porges method > FFT > AR). There was no systematic bias over the whole range of values between the two spectral approaches, while differences between the Porges method and the spectral estimates were systematically greater for larger values. Additional comparative studies are needed to explore the between-method agreement across a range of physiological conditions.
    Psychophysiology 02/2014; · 3.29 Impact Factor
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    ABSTRACT: Background. Physical aggression (PA) tends to have its onset in infancy and to increase rapidly in frequency. Very little is known about the genetic and environmental etiology of PA development during early childhood. We investigated the temporal pattern of genetic and environmental etiology of PA during this crucial developmental period.
    Psychological Medicine 01/2014; · 5.59 Impact Factor
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    ABSTRACT: Enriched environments may moderate the effect of genetic factors on prosocial leadership (gene–environment interaction, G × E). However, positive environmental experiences may also themselves be influenced by a genetic disposition for prosocial leadership (gene–environment correlation, rGE). Relating these processes to friendships, the present study examined (a) whether children with a genetic disposition for prosocial leadership possess a greater number of reciprocal friends (rGE) and (b) whether the number of reciprocal friends interacts with the effect of genetic factors on children’s prosocial leadership (G × E). The sample comprised 275 twin pairs assessed in Grade 1 (mean age 84.7 months). Reciprocal friendship and prosocial leadership behavior were measured via peer nominations. Consistent with rGE, a genetic disposition for prosocial leadership was related to an increased likelihood of friendship. Moreover, consistent with a compensation process, environmental influences played a stronger role than genetic influences in prosocial leadership when children had many friends.
    Merrill-Palmer Quarterly 01/2014; 60(2):110-141. · 1.26 Impact Factor
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    ABSTRACT: High frequency of physical aggression is the central feature of severe conduct disorder and is associated with a wide range of social, mental and physical health problems. We have previously tested the hypothesis that differential DNA methylation signatures in peripheral T cells are associated with a chronic aggression trajectory in males. Despite the fact that sex differences appear to play a pivotal role in determining the development, magnitude and frequency of aggression, most of previous studies focused on males, so little is known about female chronic physical aggression. We therefore tested here whether or not there is a signature of physical aggression in female DNA methylation and, if there is, how it relates to the signature observed in males. Methylation profiles were created using the method of methylated DNA immunoprecipitation (MeDIP) followed by microarray hybridization and statistical and bioinformatic analyses on T cell DNA obtained from adult women who were found to be on a chronic physical aggression trajectory (CPA) between 6 and 12 years of age compared to women who followed a normal physical aggression trajectory. We confirmed the existence of a well-defined, genome-wide signature of DNA methylation associated with chronic physical aggression in the peripheral T cells of adult females that includes many of the genes similarly associated with physical aggression in the same cell types of adult males. This study in a small number of women presents preliminary evidence for a genome-wide variation in promoter DNA methylation that associates with CPA in women that warrant larger studies for further verification. A significant proportion of these associations were previously observed in men with CPA supporting the hypothesis that the epigenetic signature of early life aggression in females is composed of a component specific to females and another common to both males and females.
    PLoS ONE 01/2014; 9(1):e86822. · 3.53 Impact Factor
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    ABSTRACT: Does poor language ability in early childhood increase the likelihood of physical aggression or is language ability delayed by frequent physical aggression? This study examined the longitudinal associations between physical aggression and language ability from toddlerhood to early childhood in a population sample while controlling for parenting behaviours, non-verbal intellectual functioning, and children's sex.
    PLoS ONE 01/2014; 9(11):e112185. · 3.53 Impact Factor
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    ABSTRACT: Chronic physical aggression (CPA) is characterized by frequent use of physical aggression from early childhood to adolescence. Observed in approximately 5% of males, CPA is associated with early childhood adverse environments and long-term negative consequences. Alterations in DNA methylation, a covalent modification of DNA that regulates genome function, have been associated with early childhood adversity. To test the hypothesis that a trajectory of chronic physical aggression during childhood is associated with a distinct DNA methylation profile during adulthood. We analyzed genome-wide promoter DNA methylation profiles of T cells from two groups of adult males assessed annually for frequency of physical aggression between 6 and 15 years of age: a group with CPA and a control group. Methylation profiles covering the promoter regions of 20 000 genes and 400 microRNAs were generated using MeDIP followed by hybridization to microarrays. In total, 448 distinct gene promoters were differentially methylated in CPA. Functionally, many of these genes have previously been shown to play a role in aggression and were enriched in biological pathways affected by behavior. Their locations in the genome tended to form clusters spanning millions of bases in the genome. This study provides evidence of clustered and genome-wide variation in promoter DNA methylation in young adults that associates with a history of chronic physical aggression from 6 to 15 years of age. However, longitudinal studies of methylation during early childhood will be necessary to determine if and how this methylation variation in T cells DNA plays a role in early development of chronic physical aggression.
    PLoS ONE 01/2014; 9(4):e89839. · 3.53 Impact Factor
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    ABSTRACT: Eating behaviors during childhood are related both to children's diet quality and to their weight status. A better understanding of the determinants of eating behavior during childhood is essential for carrying out effective dietary interventions. We assessed the contribution of genetic and environmental factors to variations in selected eating behaviors in early and late childhood. Information on eating behaviors came from questionnaires administered to parents of children participating in the Quebec Newborn Twin Study when the twins were 2.5 and 9 years old (n = 692 children). Dichotomous variables were derived and analyzed using structural equation modeling, as part of a classic twin study design. We performed univariate and bivariate longitudinal analyses to quantify sources of variation and covariation across ages, for several eating behavior traits. We found moderate to strong heritability for traits related to appetite such as eating too much, not eating enough and eating too fast. Univariate analysis estimates varied from 0.71 (95% CI: 0.49, 0.87) to 0.89 (0.75, 0.96) in younger children and from 0.44 (0.18, 0.66) to 0.56 (0.28, 0.78) in older children. Bivariate longitudinal analyses indicated modest to moderate genetic correlations across ages (rA varying from 0.34 to 0.58). Common genetic influences explained 17% to 43% of the phenotypic correlation between 2.5 and 9 years for these appetite-related behaviors. In 9-year-old children, food acceptance traits, such as refusing to eat and being fussy about food, had high heritability estimates, 0.84 (0.63, 0.94) and 0.85 (0.59, 0.96) respectively, while in younger children, the shared environment (i.e., common to both twins) contributed most to phenotypic variance. Variances in meal-pattern-related behaviors were mostly explained by shared environmental influences. Genetic predispositions explain a large part of the variations in traits related to appetite during childhood, though our results suggest that as children get older, appetite-related behaviors become more sensitive to environmental influences outside the home. Still, for several traits environmental influences shared by twins appear to have the largest relative importance. This finding supports the notion that familial context has considerable potential to influence the development of healthy eating habits throughout childhood.
    International Journal of Behavioral Nutrition and Physical Activity 12/2013; 10(1):134. · 3.58 Impact Factor
  • Semaine Santé et Société, Institut Santé et Société, Montreal; 11/2013
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    ABSTRACT: This study examined whether (a) a genetic disposition for physical health problems increases the risk of peer victimization and (b) peer victimization interacts with genetic vulnerability in explaining physical health problems. Participants were 167 monozygotic and 119 dizyogtic twin pairs. Physical symptoms were assessed in early childhood and early adolescence. Peer victimization was assessed in middle childhood. Genetic vulnerability for physical health problems in early childhood was unrelated to later peer victimization, but genetic vulnerability for physical health problems during early adolescence increased the risk of victimization. Victimization did not interact with genetic factors in predicting physical symptoms. Environmental, not genetic, factors had the greatest influence on the development of physical symptoms in victims. Genetic vulnerability for physical health problems in early adolescence increases the risk of peer victimization. Whether victims suffer a further increase in physical symptoms depends on the presence of protective environmental factors.
    Journal of Pediatric Psychology 10/2013; · 2.91 Impact Factor

Publication Stats

11k Citations
1,509.84 Total Impact Points


  • 1988–2014
    • Université de Montréal
      • • School of Psycho-Education
      • • Department of Social and Preventive Medicine
      Montréal, Quebec, Canada
  • 2011–2013
    • King's College London
      • MRC Social, Genetic and Developmental Psychiatry Centre
      Londinium, England, United Kingdom
    • Université René Descartes - Paris 5
      Lutetia Parisorum, Île-de-France, France
    • Hôpital Louis-H. Lafontaine
      Montréal, Quebec, Canada
    • Université de Sherbrooke
      • Department of Psychoeducation
      Sherbrooke, Quebec, Canada
    • CHU Sainte-Justine
      Montréal, Quebec, Canada
    • Centre jeunesse de Montréal-Institut universitaire
      Montréal, Quebec, Canada
    • Université Victor Segalen Bordeaux 2
      Burdeos, Aquitaine, France
  • 2007–2013
    • University of Ottawa
      • Department of Epidemiology and Community Medicine
      Ottawa, Ontario, Canada
    • University of Toronto
      Toronto, Ontario, Canada
    • University of Asia and the Pacific
      Pasig, Philippines
    • The Kings College
      Brooklyn, New York, United States
  • 1999–2013
    • Université du Québec à Montréal
      • • Department of Psychology
      • • Department of Sexology
      Montréal, Quebec, Canada
  • 1997–2013
    • McGill University
      • • Department of Psychology
      • • Department of Psychiatry
      • • Department of Medicine
      Montréal, Quebec, Canada
    • University of Texas Health Science Center at Houston
      • Center for Health Promotion and Prevention Research
      Houston, TX, United States
  • 2012
    • Université Paris Ouest Nanterre La Défense
      Nanterre, Île-de-France, France
    • Universiteit Twente
      • Institute for Innovation and Governance Studies
      Enschede, Provincie Overijssel, Netherlands
    • American College Dublin
      Dublin, California, United States
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
    • Université de Versailles Saint-Quentin
      Versailles, Île-de-France, France
  • 2002–2012
    • Laval University
      • École de Psychologie
      Québec, Quebec, Canada
  • 2008–2011
    • University College Dublin
      • School of Public Health, Physiotherapy & Population Science
      Dublin, L, Ireland
    • University of Minnesota Twin Cities
      • Department of Psychology
      Minneapolis, MN, United States
    • RAND Corporation
      Santa Monica, California, United States
  • 2010
    • Université Paris-Sud 11
      Orsay, Île-de-France, France
  • 2008–2010
    • University of Alabama
      • Department of Psychology
      Tuscaloosa, AL, United States
  • 2007–2010
    • Utrecht University
      • Division of Developmental Psychology
      Utrecht, Utrecht, Netherlands
  • 2008–2009
    • University College London
      • Division of Psychology and Language Sciences
      London, ENG, United Kingdom
  • 2007–2009
    • VU University Amsterdam
      • Department of Developmental Psychology
      Amsterdam, North Holland, Netherlands
  • 2005–2009
    • Università degli Studi di Genova
      Genova, Liguria, Italy
    • The University of Winnipeg
      • Department of Economics
      Winnipeg, Manitoba, Canada
    • Bishop's University
      Sherbrooke, Quebec, Canada
  • 2000–2009
    • Hôpital du Sacré-Coeur de Montréal
      • Center for Advanced Research in Sleep Medicine
      Montréal, Quebec, Canada
  • 2007–2008
    • Leiden University
      Leyden, South Holland, Netherlands
  • 2003–2007
    • McMaster University
      Hamilton, Ontario, Canada
    • University of New Mexico
      • Department of Sociology
      Albuquerque, NM, United States
    • Harvard University
      • Department of Psychology
      Boston, MA, United States
  • 2005–2006
    • University Medical Center Utrecht
      • Department of Child and Adolescent Psychiatry
      Utrecht, Provincie Utrecht, Netherlands
  • 2004
    • University of Oslo
      • Department of Psychology
      Oslo, Oslo, Norway
  • 1999–2003
    • Carnegie Mellon University
      • School of Public Policy & Management
      Pittsburgh, PA, United States
  • 2001
    • University of Maryland, College Park
      Maryland, United States
  • 1994–2000
    • University of Jyväskylä
      • Department of Psychology
      Jyväskylä, Province of Western Finland, Finland
  • 1996
    • Gannon University
      Erie, Pennsylvania, United States