Difficult temperament in infancy is a risk factor for forms of later internalizing and externalizing psychopathology, including depression and anxiety. A better understanding of the roots of ...difficult temperament requires assessment of its early development with a genetically informative design. The goal of this study was to estimate genetic and environmental contributions to individual differences in infant negative emotionality, their persistence over time and their influences on stability between 5 and 18 months of age.
Participants were 244 monozygotic and 394 dizygotic twin pairs (49.7% male) recruited from birth. Mothers rated their twins for negative emotionality at 5 and 18 months. Longitudinal analysis of stability and innovation between the two time points was performed in Mplus.
There were substantial and similar heritability (approximately 31%) and shared environmental (57.3%) contributions to negative emotionality at both 5 and 18 months. The trait's interindividual stability across time was both genetically- and environmentally- mediated. Evidence of innovative effects (i.e., variance at 18 months independent from variance at 5 months) indicated that negative emotionality is developmentally dynamic and affected by persistent and new genetic and environmental factors at 18 months.
In the first two years of life, ongoing genetic and environmental influences support temperamental negative emotionality but new genetic and environmental factors also indicate dynamic change of those factors across time. A better understanding of the source and timing of factors on temperament in early development, and role of sex, could improve efforts to prevent related psychopathology.
Background
Hyperactivity and inattention, the symptoms of ADHD, are marked by high levels of heritability and intergenerational transmission. Two distinct pathways of genetic intergenerational ...transmission are distinguished: direct genetic transmission when parental genetic variants are passed to the child's genome and genetic nurture when the parental genetic background contributes to the child's outcomes through rearing environment. This study assessed genetic contributions to hyperactivity and inattention in childhood through these transmission pathways.
Methods
The sample included 415 families from the Quebec Newborn Twin Study. Twins' hyperactivity and inattention were assessed in early childhood by parents and in primary school by teachers. The polygenic scores for ADHD (ADHD‐PGS) and educational attainment (EA‐PGS) were computed from twins' and parents' genotypes. A model of intergenerational transmission was developed to estimate (1) the contributions of parents' and children's PGS to the twins' ADHD symptoms and (2) whether these variances were explained by genetic transmission and/or genetic nurture.
Results
ADHD‐PGS explained up to 1.6% of the variance of hyperactivity and inattention in early childhood and primary school. EA‐PGS predicted ADHD symptoms at both ages, explaining up to 1.6% of the variance in early childhood and up to 5.5% in primary school. Genetic transmission was the only significant transmission pathway of both PGS. The genetic nurture channeled through EA‐PGS explained up to 3.2% of the variance of inattention in primary school but this association was non‐significant.
Conclusions
Genetic propensities to ADHD and education predicted ADHD symptoms in childhood, especially in primary school. Its intergenerational transmission was driven primarily by genetic variants passed to the child, rather than by environmentally mediated parental genetic effects. The model developed in this study can be leveraged in future research to investigate genetic transmission and genetic nurture while accounting for parental assortative mating.
We proposed a novel model to study intergenerational transmission of genetic risk using the polygenic score data from twin families. The model revealed that the polygenic scores for ADHD and educational attainment were contributed to individual differences in hyperactivity and inattention in childhood, with an increasing contribution in primary school. The intergenerational transmission of genetic risk occurred primarily through genetic variants immediately passed on from parents to children.
The freezing response is a universal response to threat, linked to attentive immobility and action preparation. It is relevant for acute stress coping in animals and humans, and subtle deviations in ...toddler freezing duration (absence of, or excessively long reactions) have been linked to higher risk for internalizing symptoms in adolescence. Yet, while individual freezing tendencies are relatively stable throughout life, little is known about their gene-environment aetiology.
We investigated the heritability of toddler freezing in the Quebec Newborn Twin Study (QNTS; n=508 twins) by fitting behavioural genetic models to video-coded freezing responses during a robot confrontation. Furthermore, we examined the predictive associations between toddler freezing and internalizing symptoms (anxiety and depressive symptoms), as they unfold during adolescence (ages 12–19 years) using linear mixed-effects models.
Freezing was found to be moderately heritable (45% of the variance accounted for by genetic factors). The remaining variance was explained by unique environmental factors, including measurement error. No significant contribution of shared environmental factors was noted. Additionally, shorter freezing was associated with more internalizing symptoms in adolescence at trend level, a pattern that was significant for depressive but not anxiety symptoms.
Freezing is an adaptive coping mechanism in early childhood, which is partly driven by genetic factors. Crucially, the absence or shorter duration of these behaviours may signal vulnerability to depressive problems later in life.
Canadian Institutes of Health Research and Research Fund of Quebec–Health and Society and Culture. Consolidator grant from the European Research Council (ERC_CoG-2017_772337).
Being part of a delinquent group has been shown to facilitate the expression of an individual's own delinquent propensities. However, this facilitation effect has not been investigated from a ...developmental perspective within a population heterogeneity model. Using a semiparametric mixture model with data from the Montreal Longitudinal Experimental Study, this article addresses important issues in the developmental trends of membership to delinquent groups. We explore how the rate of violent behaviors follows delinquent peer group trajectories and investigate a differential facilitation effect of delinquent peers on violence across multiple developmental pathways. Results suggest that 25% of males followed a childhood or an adolescence delinquent group affiliation trajectory. These two groups account far most of the violent acts assessed during adolescence. In addition, the rate of violent behaviors follows these developmental trajectories. Controlling for these delinquent group trajectories, we also found that being involved in a delinquent group at any specific time during adolescence is associated with an increased rate of violent behaviors, and that leaving these groups results in a decrease in violent behaviors. This facilitation effect appears homogeneous over time and across developmental trajectories. Results are discussed from a social interactional perspective.
Background: The objective of the present study was to describe the development of boys and girls during the elementary‐school years on three dimensions that conceptually and empirically represent ...risk for maladjustment. Method: Every year between kindergarten and grade six, teachers rated the impulsivity, fearfulness, and helpfulness dimensions among a sample of 1,865 children representative of kindergarten boys and girls in the province of Québec (Canada) in 1986–87. A group‐based trajectory method was used to 1) identify groups of boys and girls following distinct‐level trajectories of behaviours (on each dimension) during the elementary‐school years; 2) estimate the proportion of children in each of the identified trajectory groups; and 3) estimate the patterns of consistency and variations in trajectories. Results: The results indicated that the best models comprised three distinct‐level trajectory groups on fearfulness and helpfulness (a low, moderate, and high group) and four distinct‐level trajectory groups on impulsivity. The helpfulness and fearfulness trajectory groups were generally more stable than the impulsivity groups. The broad patterns of development were similar across sexes. However, there were more boys on the higher impulsivity trajectories and low helpfulness trajectory, while there were more girls on the high fearfulness trajectory. Conclusion: We found that behavioural consistency over middle childhood varied across trajectory groups and across dimensions, and we identified sex differences in the distribution of children in the different trajectory groups that may reflect gender‐specific risks for psychopathology.
BackgroundThe monoamine oxidase A (MAOA) gene has been shown tomoderate the impact of maltreatment on antisocial behaviour. Replicationefforts have, however, yielded inconsistent results.AimsTo ...investigate whether the interaction between the MAOAgene and violence is present across the full distribution of violence oremerges at higher levels of exposure.MethodParticipants were 327 male members of the Québec Longitudinal Study ofKindergarten Children. Exposure to violence comprised retrospectivereports of mother's and father's maltreatment, sexual and physical abuse.Conduct disorder and antisocial personality symptoms were assessed insemi-structured interviews and partner violence, property-violent crimesand arrest were self-reported.ResultsNon-linear interactions between the MAOA gene andviolence were detected, suggesting that the genetic moderation may comeabout once a certain level of violence is experienced.ConclusionsFuture studies should investigate the mechanisms translating substantialviolence exposure, which could, subsequently, trigger the expression ofgenetically based differences in antisocial behaviour.
Suicidal behaviors in young individuals represent an important public health problem. Understanding their natural history and relationships would therefore be of clinical and research value. In this ...study, we examined the natural histories of several suicidal behaviors and investigated two conceptual models of suicidality (dimensional and categorical) in the context of adolescent and adult-onset suicide attempts.
Participants were members of a prospectively studied, representative, population-based school cohort followed since age 6 (n = 3017) through mid-adolescence (n = 1715) to their early twenties (n = 1684). Outcome measures included suicidal ideation, attempts and completions.
Approximately one in 500 individuals died by suicide. About 33% had suicidal ideas and 9.3% made at least one suicide attempt. Over half (4.9%) of the self-reported attempters made their first attempt before age 18. With the exception of current suicidal ideas, non-fatal suicidal behaviors were more prevalent in females. In general, parental and cross-sectional self-reports underestimated suicidality rates. Aikaike (AIC) and Bayesian (BIC) information criteria suggested the ordinal model, and dimensional conceptualization of suicide attempts of different onset age, to be more optimal than its multinomial/categorical counterpart (ordinal: AIC 567.55, BIC 635.67; multinomial: AIC 616.59, BIC 723.83). Both models, nevertheless, identified five common factors of relevance to suicidal diathesis: gender, disruptive disorders, childhood anxiousness and abuse, and suicidal thoughts.
Non-fatal suicidal behaviors in adolescents and young adults are more common than suggested by cross-sectional studies and parental reports. The dimensional model may be more useful in explaining the relationship of suicide attempts of different age of onset.
Adults exhibiting severe impulsive and aggressive behaviors have multiple indices of low serotonin (5-HT) neurotransmission. It remains unclear though whether low 5-HT mediates the behavior or ...instead reflects a pre-existing vulnerability trait.
In the present study, positron emission tomography with the tracer alpha-(11)Cmethyl-L-tryptophan ((11)C-AMT) was used to compare 5-HT synthesis capacity in two groups of adult males from a 21-year longitudinal study (mean age +/- SD: 27.1+/-0.7): individuals with a history of childhood-limited high physical aggression (C-LHPA; N = 8) and individuals with normal (low) patterns of physical aggression (LPA; N = 18). The C-LHPA males had significantly lower trapping of (11)C-AMT bilaterally in the orbitofrontal cortex and self-reported more impulsiveness. Despite this, in adulthood there were no group differences in plasma tryptophan levels, genotyping, aggression, emotional intelligence, working memory, computerized measures of impulsivity, psychosocial functioning/adjustment, and personal and family history of mood and substance abuse disorders.
These results force a re-examination of the low 5-HT hypothesis as central in the biology of violence. They suggest that low 5-HT does not mediate current behavior and should be considered a vulnerability factor for impulsive-aggressive behavior that may or may not be expressed depending on other biological factors, experience, and environmental support during development.
Some evidence suggests that the prevalence of Borderline Personality Disorder (BPD) is elevated among male criminal offenders. It is not presently known whether offending, and violent offending, are ...limited to those presenting comorbid Antisocial Personality Disorder (ASPD) who have a childhood history of conduct problems and whether offending is linked to psychopathic traits.
A community sample of 311 males followed from age 6 to 33 years, one third of whom had a criminal charge between ages 18 and 24, completed diagnostic interviews and the Psychopathy Checklist-Revised interview. Information on childhood included parent-reported family characteristics and teacher-rated of hurtful and uncaring behaviours, conduct problems, hyperactivity and inattention, and anxiety at age 6, 10, and 12 years. Health files were obtained as were records of criminal convictions from age 12 to 33.
At age 33, 4% of the men presented BPD and not ASPD, 16% ASPD and not BPD, 8% BPD + ASPD, and 72% neither disorder (ND). Comorbid disorders were common: BPD were distinguished by high levels of anxiety disorders, BPD and BPD + ASPD by depression disorders, and BPD, BPD + ASPD, and ASPD by substance dependence. Official files indicated use of health services by all participants. One-third of participants with BPD and BPD + ASPD acquired a diagnosis of a personality disorder. More than one-third of participants with BPD + ASPD obtained scores indicative of the syndrome of psychopathy. Convictions for violent crimes varied across groups: In adolescence, BPD none, BPD + ASPD 16%, ASPD 16%, and ND 3.6%; from age 18 to 33, BPD 18%, ASPD 19%, BPD + ASPD 52%, and ND 4.4%. Offenders with BPD + ASPD were convicted, on average, for four times more violent crimes than offenders with ASPD and seven times more than ND offenders. In childhood, men with BPD + ASPD and with ASPD had obtained similarly elevated ratings for disruptive behaviours as compared to ND.
BPD comorbid with ASPD was associated with violent criminal offending in adolescence and most strongly in adulthood, elevated levels of psychopathic traits, and childhood disruptive behaviour. BPD showed similar characteristics but to a much less degree.
Emerging Substance Use of Teenagers With ADHD Belanger, Richard E., MD; Lapointe, Kim Guay, BA; Poliakova, Natalia, PhD ...
Journal of adolescent health,
February 2016, Letnik:
58, Številka:
2
Journal Article
PDF
