ORCHIDS: an observational randomized controlled trial on childhood differential susceptibility

Incredible years parenting program buffers prospective association between parent-reported harsh parenting and epigenetic age deceleration in children with externalizing behavior

Harsh parenting has been shown to increase the risk of physical and mental health problems in later life. To improve our understanding of these risks and how they can be mitigated, we investigated associations of harsh parenting with a clinically relevant biomarker, epigenetic age deviation (EAD), using data from a randomized-control trial of the Incredible Years (IY) parenting program. This study included 281 children aged 4-8 years who were screened for heightened externalizing behavior and whose parents were randomly allocated to either IY or care-as-usual (CAU). Parents reported on their own parenting practices and their child's externalizing behavior at baseline and at a follow-up assessment approximately three years later. Epigenetic age, based on the Pediatric Buccal Epigenetic (PedBE) clock, was estimated from child DNA methylation derived from saliva collected at the follow-up assessment. PedBE clock estimates were regressed on chronological age as a measure of EAD. Moderation analyses using multiple regression revealed that harsher parenting at baseline predicted epigenetic age deceleration in children that received CAU (b = -.21, 95% CI[-0.37, -0.05]), but no association was found in children whose parents were allocated to IY (b = -.02, 95% CI [-0.13, 0.19]). These results highlight a prospective association between harsh parenting and children's EAD and indicate a potential ameliorating effect of preventive intervention. Future work is needed to replicate these findings and understand individual differences in children's responses to harsh parenting in relation to epigenetic aging.

Optimizing treatment environments for trait sensitivity in eating disorders

Research has identified trait sensitivity as a potential risk factor and treatment target of eating disorders. Conceptualizations of trait sensitivity have depicted individuals with high and low trait sensitivity metaphorically as orchids and dandelions, highlighting their responsiveness to environmental conditions and associated outcomes. While orchids require careful tending to survive, with such care, they emerge extraordinary. In contrast, dandelions can survive a broad range of environmental conditions. Within a scientific framework, trait sensitivity can be conceptualized as neurobiologically-based, with heightened sensory, interoceptive, interpersonal, and emotional processing. While trait sensitivity may increase susceptibility to eating disorders, when therapists view these traits through the lens of environmental responsiveness, they can facilitate their client's inherent resilience and potential. Incorporating a model of trait sensitivity into eating disorders treatment using psychoeducation, modifying environmental stimuli, and selecting optimal interventions has the potential to increase treatment engagement, deepen therapeutic collaboration, and improve outcomes.

The peril and promise of sensitivity in eating disorders

Differential susceptibility, a reconceptualization of the diathesis-stress model of psychopathology, describes gene-environment interactions that reflect individual differences in responsiveness to environmental influences, both detrimental and beneficial. This model has been described metaphorically by the classification of orchids, which thrive under optimal care but wither under adverse conditions, and dandelions, which weather broad environmental circumstances but are less responsive to careful cultivation. Etiological research in the field of eating disorders has largely focused on the identification of specific behavioral phenotypes, temperamental traits, genotypes and neurobiological processes that confer risk. In this article, we propose that these putative vulnerability factors represent phenotypes and endophenotypes of a genetic predisposition towards environmental sensitivity. We assert that this sensitivity not only transmits eating disorder risk but also confers resilience, depending on the circumstances. In particular, we propose that differential susceptibility can be used as a framework to organize disparate temperamental and neurobiological findings and their complex interplay with various developmental, environmental and sociocultural influences to increase eating disorder risk and treatment responsiveness. Finally, we assert that viewed through the lens of differential susceptibility, sensitivity can be leveraged to refine our interventions and develop novel treatment and prevention strategies to support favorable outcomes for individuals with eating disorders.

Longer-Term Outcomes of the Incredible Years Parenting Intervention

Conduct problems can develop into behavior disorders and put children at risk for other mental health problems. Parenting interventions have been shown to successfully reduce conduct problems and are often expected to prevent the development of broader mental health problems. Few studies have evaluated the longer-term and broader effects of these interventions. To what extent are parenting intervention effects sustained in the years after the intervention? And do effects pertain to conduct problems specifically, or do they also affect broader aspects of children's mental health? We used a randomized controlled trial to assess the longer-term (2.5 years) effects of the Incredible Years parenting intervention on children's conduct problems in an indicated prevention setting (N = 387; 79% retention rate). Using a multi-method (survey and computerized tasks) and multi-informant (parents, teachers, and children) approach, we tested whether initial effects on conduct problems were sustained, and whether Incredible Years had broader effects on children's peer problems, emotional problems, attention-deficit/hyperactivity disorder (ADHD) symptoms, attention and inhibition deficits, and service use. Incredible Years, relative to control (no intervention), led to sustained reductions in parent-reported conduct problems (Cohen's d = 0.31), but not teacher- and child-reported conduct problems. There were no broader benefits: Incredible Years did not reduce children's peer problems, emotional problems, ADHD-symptoms, attention and inhibition deficits, or their service use. Improvements in parents' perceptions of child conduct problems sustained until 2.5 years later. Our findings do not show benefits of Incredible Years as a preventive intervention for children's broader mental health.

When mummy and daddy get under your skin: A new look at how parenting affects children's DNA methylation, stress reactivity, and disruptive behavior

Child maltreatment is a global phenomenon that affects the lives of millions of children. Worldwide, as many as one in three to six children encounter physical, sexual, or emotional abuse from their caregivers. Children who experience abuse often show alterations in stress reactivity. Although this alteration may reflect a physiological survival response, it can nevertheless be harmful in the long run-increasing children's disruptive behavior and jeopardizing their development in multiple domains. But can we undo this process in at-risk children? Based on several lines of pioneering research, we hypothesize that we indeed can. Specifically, we hypothesize that highly dysfunctional parenting leads to an epigenetic pattern in children's glucocorticoid genes that contributes to stress dysregulation and disruptive behavior. However, we also hypothesize that it is possible to "flip the methylation switch" by improving parenting with known-effective parenting interventions in at-risk families. We predict that improved parenting will change methylation in genes in the glucocorticoid pathway, leading to improved stress reactivity and decreased disruptive behavior in children. Future research testing this theory may transform developmental and intervention science, demonstrating how parents can get under their children's skins-and how this mechanism can be reversed.

Families Who Benefit and Families Who Do Not: Integrating Person- and Variable-Centered Analyses of Parenting Intervention Responses

OBJECTIVE

Families with disruptive child behavior are typically referred to services based on children's behavior alone, rather than on underlying mechanisms of disruptive behavior. Yet, the presence of the precise mechanisms targeted by services might be essential for intervention success. We integrated person- and variable-centered approaches to test whether families with combined disruptive child behavior and harsh/inconsistent parenting indeed benefit most from a behavioral parenting intervention in indicated prevention context, compared to families with disruptive child behavior but less harsh/inconsistent parenting, and families with less severe disruptive behavior.

METHOD

Families (N = 387) of children aged 4 to 8 years (disruptive behavior >75^th percentile) participated in a randomized trial of the Incredible Years parenting intervention (Trial NTR3594, www.trialregister.nl). We identified different response trajectories and tested whether families with combined child and parenting difficulties had a higher probability of responding well, compared to families with only child difficulties or less severe difficulties.

RESULTS

Most intervention group families (82%) showed a nonresponse trajectory. A minority (18%) showed a response trajectory with strong reductions in disruptive behavior (Cohen's d =1.45). As expected, families with both child and parenting difficulties were most likely to respond: 20% more than families with only child difficulties, and 40% more than families with less severe difficulties.

CONCLUSION

Incredible Years, as an indicated prevention program, benefits mainly families in which the mechanisms targeted by the intervention (ie, harsh/inconsistent parenting) is actually present, rather than all families. Careful matching of children to services based on assessments of both child and parenting behavior seems critical for intervention success.

CLINICAL TRIAL REGISTRATION INFORMATION

ORCHIDS: Study on Children's Genetic Susceptibility to Their Environment; https://www.trialregister.nl; 3594.

Mechanisms of child behavior change in parent training: Comment on Weeland et al. (2018)

Recently in this journal, Weeland et al. (2018) published a thought-provoking article reporting moderating effects of children's serotonin transporter-linked polymorphisms (5-HTTLPR) on negative parenting during prevention with the Incredible Years series. Participants were parents and young children of 387 families enrolled in the Observational Randomized Control Trial of Childhood Differential Susceptibility study. An equally important finding, which we focus on in this comment, involved null effects for all tests of parenting as a mediator of prevention-induced improvements in children's externalizing behavior. Although such findings may seem surprising, both confirmations of and failures to confirm parenting change as a mediator of child behavior change are common in the prevention and intervention literatures. In this comment, we explore likely reasons for heterogeneity in findings, including both moderators of treatment effect size and methods used to test mediation. Common moderators of prevention and intervention response to Incredible Years include dose, parenting problems at intake, high-risk versus clinical nature of samples, how parenting is measured, and whether child training is included with parent training. All of these moderators affect power to detect mediation. We then discuss conceptual criteria for testing mediation in randomized clinical trials, and problems with interpreting mediating paths in cross-lag panel models. Although the gene effect reported by Weeland et al. is important, their cross-lag panel models do not provide strong tests of parenting as a mediator of child behavior change. We conclude with recommendations for testing mediation in randomized clinical trials.

What changes when? A reply to Beauchaine and Slep

In their commentary, Beauchaine and Slep (2018) raise important issues regarding research on behavioral parenting training (BPT). In this reply we highlight key points of agreement and respond to issues that we feel require clarification. BPT has been repeatedly proven effective in decreasing disruptive child behavior (also in the work of our research team). Yet, there is much to learn about for whom and how BPT is effective. Specifically, assessing the how (i.e., mediation) comes with many challenges. One of these challenges is taking into account the timeline of change, and being able to infer causal mechanisms of change. We argue that cross-lagged panel models (which we, and many other scholars, used) are a valid and valuable method for testing mediation. At the same time, our results raise important questions, specifically about the timing and form of expected changes in parenting and child behavior after BPT. For example, are these changes linear and gradual or do they happen more suddenly? To select the appropriate design, assessment tools, and statistical models to test mediation, we need to state detailed hypotheses on what changes when. An important next step might be to assess multiple putative mediators on different timescales, not only before and after, but specifically also during BPT.

Dutch Norms for the Eyberg Child Behavior Inventory: Comparisons with other Western Countries

The Eyberg Child Behavior Inventory (ECBI) is one of the most widely used and well-validated parent rating scales for children's disruptive behavior. This screening instrument is a short, targetted and easy to implement inventory with good psychometric properties and is normed for different countries, among which the United States, Spain, Sweden and Norway. The ECBI has been successfully used for research and clinical purposes, in several countries including The Netherlands. To date, Dutch studies have relied on Scandinavian or US norm scores. However, this may be problematic because of cross-cultural differences in the degree to which certain behaviors are seen as problematic by parents. The main goal of this paper therefore was to obtain norm scores for The Netherlands among 6462 Dutch children aged 4 to 8 years (Mage = 6.37 years; SD = 1.32; 50.6% boys). In line with previous research, we found small differences on the mean sum scores across children of different ages (intensity scale) and gender (intensity and problem scale). Therefore, Dutch norm scores were provided age- and gender specific. Our results showed that disruptive behavior of children in the most rural areas was reported as occurring less frequently and was seen as less problematic by parents compared to the disruptive behavior of children in less rural areas. Finally, we found that Dutch norm scores on the ECBI were significantly lower than US norm scores, and significantly higher on the intensity scale (but not the problem scale) than Norwegian and Swedish norm scores.

Could scale-up of parenting programmes improve child disruptive behaviour and reduce social inequalities? Using individual participant data meta-analysis to establish for whom programmes are effective and cost-effective

Background

Child disruptive behavioural problems are a large and costly public health problem. The Incredible Years®(IY) parenting programme has been disseminated across the UK to prevent this problem and shown to be effective in several trials. It is vital for policy to know for which families IY is most effective, to be sure that it helps reduce, rather than widen, socioeconomic inequalities. Individual trials lack power and generalisability to examine differential effects; conventional meta-analysis lacks information about within-trial variability in effects.

Objectives

To overcome these limitations by pooling individual-level data from the IY parenting trials in Europe to examine to what extent it benefits socially disadvantaged families. Secondary objectives examine (1) additional moderators of effects on child behaviour, (2) wider health benefits and potential harms and (3) costs, cost-effectiveness and potential long-term savings.

Design

Individual participant data meta-analysis of 14 randomised trials of the IY parenting intervention.

Settings

UK (eight trials), the Netherlands, Ireland, Norway, Sweden and Portugal.

Participants

Data were from 1799 families, with children aged 2–10 years (mean 5.1 years; 63% boys).

Interventions

IY Basic parenting programme.

Main outcome measures

Primary outcome was disruptive child behaviour, determined by the Eyberg Child Behavior Inventory Intensity scale (ECBI-I). Secondary outcomes included self-reported parenting practices, parenting stress, mental health, children’s attention deficit hyperactivity disorder (ADHD) and emotional symptoms.

Results

There were no differential effects of IY on disruptive behaviour in families with different levels of social/socioeconomic disadvantage or differential effects for ethnic minority families, families with different parenting styles, or for children with comorbid ADHD or emotional problems or of different ages. Some moderators were found: intervention effects were strongest in children with more severe baseline disruptive behaviour, in boys, and in children with parents who were more depressed. Wider health benefits included reduced child ADHD symptoms, greater parental use of praise, and reduced harsh and inconsistent discipline. The intervention did not improve parental depression, stress, self-efficacy or children’s emotional problems. Economic data were available for five UK and Ireland trials (maximumn = 608). The average cost per person of the IY intervention was £2414. The probability that the IY intervention is considered cost-effective is 99% at a willingness to pay of £145 per 1-point improvement on the ECBI-I. Estimated longer-term savings over 20 years range from £1000 to £8400 per child, probably offsetting the cost of the intervention.

Limitations

Limitations include a focus on one parenting programme; the need to make assumptions in harmonising data; and the fact that data addressed equalities in the effectiveness of, not access to, the intervention.

Conclusions

There is no evidence that the benefits of the IY parenting intervention are reduced in disadvantaged or minority families; benefits are greater in the most distressed families, including parents who are depressed. Thus, the intervention is unlikely to widen socioeconomic inequalities in disruptive behaviour and may have effects in narrowing inequalities due to parent depression. It was as likely to be effective for older as for younger children. It has wider benefits for ADHD and parenting and is likely to be considered to be cost-effective. Researchers/funders should encourage data sharing to test equity and other moderator questions for other interventions; further research is needed on enhancing equality of access to interventions.

Funding

The National Institute for Health Research Public Health Research programme.

Does the Incredible Years reduce child externalizing problems through improved parenting? The role of child negative affectivity and serotonin transporter linked polymorphic region (5-HTTLPR) genotype

In a randomized controlled trial, the Observational Randomized Controlled Trial of Childhood Differential Susceptibility (ORCHIDS study), we tested whether observed parental affect and observed and reported parenting behavior are mechanisms of change underlying the effects of the behavioral parent training program the Incredible Years (IY). Furthermore, we tested whether some children are more susceptible to these change mechanisms because of their temperamental negative affectivity and/or serotonin transporter linked polymorphic region (5-HTTLPR) genotype. Participants were 387 Dutch children between 4 and 8 years of age (M age = 6.31, SD = 1.33; 55.3% boys) and their parents. Results showed that although IY was successful in improving parenting behavior and increasing parental positive affect, these effects did not explain the significant decreases in child externalizing problems. We therefore found no evidence for changes in parenting behavior or parental affect being the putative mechanisms of IY effectiveness. Furthermore, intervention effects on child externalizing behavior were not moderated by child negative affectivity or 5-HTTLPR genotype. However, child 5-HTTLPR genotype did moderate intervention effects on negative parenting behavior. This suggests that in research on behavioral parent training programs, "what works for which parents" might also be an important question.

Intervention Effectiveness of The Incredible Years: New Insights Into Sociodemographic and Intervention-Based Moderators

We tested the effectiveness of the preventive behavioral parent training (BPT) program, The Incredible Years (IY), and the independent effects of previously suggested sociodemographic and intervention-based moderator variables (i.e., initial severity of externalizing problem behavior, child gender, social economic status, family composition, and number of sessions parents attended), in a large-scale randomized controlled trial. Questionnaire and observation data from 387 parents and children ages 4-8 years (M_age= 6.21, SD = 1.33, 55.30% boys) across pretest, posttest, and 4-month follow-up were analyzed, using full intention-to-treat analyses and correcting for multiple testing. IY was successful in decreasing parent-reported child externalizing behavior (Cohen's d = 0.20 at posttest, d = 0.08 at follow-up), increasing parent-reported (d = 0.49, d = 0.45) and observed (d = 0.06, d = 0.02) positive parenting behavior, and decreasing parent-reported negative parenting behavior (d = 0.29, d = 0.25). No intervention effects were found for reported and observed child prosocial behavior, observed child externalizing behavior, and observed negative parenting behavior. Out of 40 tested moderation effects (i.e., 8 Outcomes × 5 Moderators), only three significant moderation effects appeared. Thus, no systematic evidence emerged for moderation of IY effects. The present multi-informant trial demonstrated that many previously suggested moderators might not be as potent in differentiating BPT effects as once thought.

Genetic Moderation of Intervention Efficacy: Dopaminergic Genes, The Incredible Years, and Externalizing Behavior in Children

This study investigated whether children scoring higher on a polygenic plasticity index based on five dopaminergic genes (DRD4, DRD2, DAT1, MAOA, and COMT) benefited the most from the Incredible Years (IY) parent program. Data were used from a randomized controlled trial including 341 Dutch families with 4- to 8-year-old children (55.7% boys) showing moderate to high levels of problem behavior. IY proved to be most effective in decreasing parent-reported (but not observed) externalizing behavior in boys (but not girls) carrying more rather than fewer dopaminergic plasticity alleles; this Gene × Intervention effect was most pronounced in the case of boys whose parents' manifested the most positive change in parenting in response to the intervention. These results proved robust across a variety of sampling specifications (e.g., intention to treat, ethnicity).