The development of temperament from a behavioral genetics perspective

Negative emotionality as a candidate mediating mechanism linking prenatal maternal mood problems and offspring internalizing behaviour

Negative emotionality (NE) was evaluated as a candidate mechanism linking prenatal maternal affective symptoms and offspring internalizing problems during the preschool/early school age period. The participants were 335 mother-infant dyads from the Maternal Adversity, Vulnerability and Neurodevelopment project. A Confirmatory Bifactor Analysis (CFA) based on self-report measures of prenatal depression and pregnancy-specific anxiety generated a general factor representing overlapping symptoms of prenatal maternal psychopathology and four distinct symptom factors representing pregnancy-specific anxiety, negative affect, anhedonia and somatization. NE was rated by the mother at 18 and 36 months. CFA based on measures of father, mother, child-rated measures and a semistructured interview generated a general internalizing factor representing overlapping symptoms of child internalizing psychopathology accounting for the unique contribution of each informant. Path analyses revealed significant relationships among the general maternal affective psychopathology, the pregnancy- specific anxiety, and the child internalizing factors. Child NE mediated only the relationship between pregnancy-specific anxiety and the child internalizing factors. We highlighted the conditions in which prenatal maternal affective symptoms predicts child internalizing problems emerging early in development, including consideration of different mechanistic pathways for different maternal prenatal symptom presentations and child temperament.

RDoC and Psychopathology among Youth: Misplaced Assumptions and an Agenda for Future Research

Now over 10 years old, the Research Domain Criteria (RDoC) has gained impressive traction in the adult psychopathology literature, but enthusiasm among child and adolescent psychopathologists lags somewhat behind. We consider possible reasons why RDoC has not been embraced fully in the child and adolescent literatures. We emphasize common, interrelated, and sometimes outdated assumptions that impede scientific progress that RDoC could facilitate. Traditionally, child and adolescent psychopathologists have used behavioral syndromes as gold standards against which biological markers are validated, even though behavioral syndromes are often measured with less precision; sought to identify large main effects of single biological functions on single behavioral syndromes, thereby ignoring (even if implicitly) the overwhelming etiological complexity of psychopathology; expected 1:1 correspondencies between biological functions and behaviors, despite evidence that core biological systems subserving behavior are functionally interdependent (i.e., modulate one another); and failed to consider neurobiological mechanisms of homotypic and heterotypic comorbidity and continuity. Using examples from our work, we show how a developmental, RDoC-informed approach to externalizing behavior enriches our understanding of psychopathology. We also provide an agenda for future research, which includes calls to (1) adopt neural-systems-first approaches over disorder-first approaches when studying psychopathology, (2) eschew biological reductionism by integrating environmental risk mediators into our etiopathophysiological models, (3) integrate neural vulnerabilities into the empirical latent structure of psychopathology, and (4) replace null hypothesis significance testing with computational approaches that accommodate etiological complexity by evaluating functional dependencies among RDoC constructs, including positive valence systems (approach), negative valence systems (avoidance), and arousal/regulatory systems (self-regulation).

The genetic and environmental origins of emotional and cognitive empathy: Review and meta-analyses of twin studies

Empathy is considered a cornerstone of human social experience, and as such has been widely investigated from psychological and neuroscientific approaches. To better understand the factors influencing individual differences in empathy, we reviewed and meta-analyzed the behavioral genetic literature of emotional empathy- sharing others' emotions (k=13), and cognitive empathy- understanding others' emotions (k = 15), as manifested in twin studies. Results showed that emotional empathy is more heritable, 48.3 % [41.3 %-50.6 %], than cognitive empathy, 26.9 % [18.1 %-35.8 %]. Moreover, cognitive empathy as examined by performance tests was affected by the environment shared by family members, 11.9 % [2.6 %-21.0 %], suggesting that emotional understanding is influenced, to some degree, by environmental factors that have similar effects on family members beyond their genetic relatedness. The effects of participants' age and the method used to asses empathy on the etiology of empathy were also examined. These findings have implications for understanding how individual differences in empathy are formed. After discussing these implications, we suggest theoretical and methodological future research directions that could potentially elucidate the relations between genes, brain, and empathy.

Nonsuicidal Self-Injury and Suicidal Behaviors in Girls: The Case for Targeted Prevention in Preadolescence

Non-suicidal self-injury (NSSI) affects 15-20% of adolescents-disproportionately girls-and is a strong predictor of eventual suicide attempts and suicide. Many girls now initiate NSSI before age 10. These early-starters exhibit greater frequency of NSSI, use more diverse methods, and are hospitalized more often, yet there are no empirically supported prevention programs for preadolescents. Obstacles to prevention include ascertaining who is sufficiently vulnerable and specifying mechanistic intervention targets. Recent research indicates that (1) preadolescent girls with ADHD who are also maltreated are at alarming risk for NSSI and suicide attempts by adolescence, and (2) the conjoint effects of these vulnerabilities are sufficiently potent for targeted prevention. Research also indicates that existing interventions are effective in altering child- and family-level mechanisms of NSSI. These interventions alter neurobiological markers of vulnerability, which can be used as proximal efficacy signals of prevention response, without waiting for NSSI and suicide attempts to emerge.

Temperament and Character Inventory in Bipolar Disorder versus Healthy Controls and Modulatory Effects of 3 Key Functional Gene Variants

BACKGROUND

Bipolar disorder (BD) has been associated with temperamental and personality traits, although the relationship is still to be fully elucidated. Several studies investigated the genetic basis of temperament and character, identifying catechol-O-methyltransferase (COMT), brain derived neurotrophic factor (BDNF), and serotonin transporter (5-HTT) gene variants as strong candidates.

METHODS

In the GECO-BIP study, 125 BD patients and 173 HC were recruited. Subjects underwent to a detailed assessment and the temperament and character inventory 125 items (TCI) was administrated. Three functional genetic variants within key candidate genes (COMT rs4680, BDNF rs6265, and the serotonin-transporter-linked polymorphic region (5-HTTLPR)) were genotyped. Univariate and multivariate analyses were performed.

RESULTS

Compared to HC, BD patients showed higher scores in novelty seeking (NS; p = 0.001), harm avoidance (HA; p < 0.001), and self transcendence (St; p < 0.001), and lower scores in self directness (p < 0.001) and cooperativeness (p < 0.001) TCI dimensions. Concerning the genetic analyses, COMT rs4680 was associated with NS in the total sample (p = 0.007) and in the male subsample (p = 0.022). When performing the analysis in the HC and BD samples, the association was confirmed only in HC (p = 0.012), and in the HC male subgroup in particular (p = 0.004). BDNF rs6265 was associated with St in the BD group (p = 0.017).

CONCLUSION

COMT rs4680 may modulate NS in males in the general population. This effect was not detected in BD patients, probably because BD alters the neurobiological basis of some TCI dimensions. BDNF rs6265 seems to modulate St TCI dimension only in BD patients, possibly modulating the previously reported association between rs6265 and BD treatment response. Further studies are needed to confirm our findings.

Prenatal maternal depression and child serotonin transporter linked polymorphic region (5-HTTLPR) and dopamine receptor D4 (DRD4) genotype predict negative emotionality from 3 to 36 months

Prenatal maternal depression and a multilocus genetic profile of two susceptibility genes implicated in the stress response were examined in an interaction model predicting negative emotionality in the first 3 years. In 179 mother-infant dyads from the Maternal Adversity, Vulnerability, and Neurodevelopment cohort, prenatal depression (Center for Epidemiologic Studies Depressions Scale) was assessed at 24 to 36 weeks. The multilocus genetic profile score consisted of the number of susceptibility alleles from the serotonin transporter linked polymorphic region gene (5-HTTLPR): no long-rs25531(A) (LA: short/short, short/long-rs25531(G) [LG], or LG/LG] vs. any LA) and the dopamine receptor D4 gene (six to eight repeats vs. two to five repeats). Negative emotionality was extracted from the Infant Behaviour Questionnaire-Revised at 3 and 6 months and the Early Child Behavior Questionnaire at 18 and 36 months. Mixed and confirmatory regression analyses indicated that prenatal depression and the multilocus genetic profile interacted to predict negative emotionality from 3 to 36 months. The results were characterized by a differential susceptibility model at 3 and 6 months and by a diathesis-stress model at 36 months.

Emerging Trends in Behavioral Genetic Studies of Child Temperament

In this article, we describe three emerging trends in the application of behavioral genetic methods to the study of temperament. The trends-using multiple methods to assess temperament, considering contextual influences on temperament, and evaluating the structure of temperament-have been well studied in the phenotypic literature, but adding a behavioral genetic perspective can enrich our understanding of temperament. We review recent behavioral genetic research in each of these areas and discuss its implications.

Child care, socio-economic status and problem behavior: a study of gene-environment interaction in young Dutch twins

The influences of formal child care before age 4 on behavioral problems at 3, 5, and 7 years of age were assessed in 18,932 Dutch twins (3,878 attended formal child care). The effect of formal child care was studied on the average level of problem behavior and as moderator of genetic and non-genetic influences, while taking into account effects of sex and parental socio-economic status (SES). There was a small association between attending formal child care and higher externalizing problems, especially when SES was low. Heritability was lower for formal child care and in lower SES conditions. These effects were largest at age 7 and for externalizing problems. In 7 year-old boys and girls, the difference in heritability between the formal child care group of low SES and the home care group of high SES was 30% for externalizing and ~20% for internalizing problems. The decrease in heritability was explained by a larger influence of the environment, rather than by a decrease in genetic variance. These results support a bioecological model in which heritability is lower in circumstances associated with more problem behavior.

Comorbidities and continuities as ontogenic processes: toward a developmental spectrum model of externalizing psychopathology

Research on child and adolescent mental health problems has burgeoned since the inaugural issue of Development and Psychopathology was published in 1989. In the quarter century since, static models of psychopathology have been abandoned in favor of transactional models, following the agenda set by editor Dante Cicchetti and other proponents of the discipline. The transactional approach, which has been applied to autism, depression, self-injury, and delinquency, (a) specifies vulnerabilities and risk factors across multiple levels of analysis spanning genes to cultures, (b) identifies multifinal and equifinal pathways to psychopathology, and (c) transcends traditional disciplinary boundaries. However, as noted by Rutter and Sroufe (2000), specific mechanisms of continuity, discontinuity, and comorbidity of psychopathology must be identified if we wish to understand etiology fully. In this article, we present a model of early-onset externalizing behavior in which comorbidities and continuities are viewed as ontogenic processes: products of complex longitudinal transactions between interdependent individual-level vulnerabilities (e.g., genetic, epigenetic, allostatic) and equally interdependent contextual risk factors (e.g., coercive parenting, deviant peer group affiliations, neighborhood criminality). Through interactions across levels of analysis, some individuals traverse along the externalizing spectrum, beginning with heritable trait impulsivity in preschool and ending in antisociality in adulthood. In describing our model, we note that (a) the approach outlined in the DSM to subtyping externalizing disorders continues to obscure developmental pathways to antisociality, (b) molecular genetics studies will likely not identify meaningful subtypes of externalizing disorder, and (c) ontogenic trait approaches to psychopathology are much more likely to advance the discipline in upcoming years.