The pharmacological treatment of aggression in children and adolescents with conduct disorder. Do callous-unemotional traits modulate the efficacy of medication?

Treatment of childhood disruptive behavior disorders and callous-unemotional traits: a systematic review and two multilevel meta-analyses

BACKGROUND

Children with callous-unemotional (CU) traits are at high lifetime risk of antisocial behavior. It is unknown if treatments for disruptive behavior disorders are as effective for children with CU traits (DBD+CU) as those without (DBD-only), nor if treatments directly reduce CU traits. Separate multilevel meta-analyses were conducted to compare treatment effects on DBD symptoms for DBD+CU versus DBD-only children and evaluate direct treatment-related reductions in CU traits, as well as to examine moderating factors for both questions.

METHODS

We systematically searched PsycINFO, PubMed, Cochran Library (Trials), EMBASE, MEDLINE, APA PsycNet, Scopus, and Web of Science. Eligible studies were randomized controlled trials, controlled trials, and uncontrolled studies evaluating child-focused, parenting-focused, pharmacological, family-focused, or multimodal treatments.

RESULTS

Sixty studies with 9,405 participants were included (Mage  = 10.04, SDage  = 3.89 years, 25.09% female, 44.10% racial/ethnic minority). First, treatment was associated with similar reductions in DBD symptoms for DBD+CU (SMD = 1.08, 95% CI = 0.45, 1.72) and DBD-only (SMD = 1.01, 95% CI = 0.38, 1.64). However, DBD+CU started (SMD = 1.18, 95% CI = 0.57, 1.80) and ended (SMD = 0.73, p < .001; 95% CI = 0.43, 1.04) treatment with more DBD symptoms. Second, although there was no overall direct effect of treatment on CU traits (SMD = .09, 95% CI = -0.02, 0.20), there were moderating factors. Significant treatment-related reductions in CU traits were found for studies testing parenting-focused components (SMD = 0.21, 95% CI = 0.06, 0.35), using parent-reported measures (SMD = 0.16, 95% CI = 0.04, 0.28), rated as higher quality (SMD = 0.26, 95% CI = 0.13, 0.39), conducted outside the United States (SMD = 0.19, 95% CI = 0.05, 0.32), and with less than half the sample from a racial/ethnic minority group (SMD = 0.15, 95% CI = 0.002, 0.30).

CONCLUSIONS

DBD+CU children improve with treatment, but their greater DBD symptom severity requires specialized treatment modules that could be implemented alongside parenting programs. Conclusions are tempered by heterogeneity across studies and scant evidence from randomized controlled trials.

Contemporary diagnosis and treatment of conduct disorder in youth

INTRODUCTION

Conduct disorder (CD) is characterized by repetitive and persistent antisocial behaviors, being among the most frequently reported reasons of referral in youth. CD is a highly heterogeneous disorder, with possible specifiers defined according to age at onset, Limited Prosocial Emotions (LPE) otherwise known as Callous-Unemotional (CU) traits, Emotional Dysregulation (ED), and patterns of comorbidity, each with its own specific developmental trajectories.

AREAS COVERED

The authors review the evidence from published literature on the clinical presentations, diagnostic procedures, psychotherapeutic and psychoeducational approaches, and pharmacological interventions from RCT and naturalistic studies in youth. Evidence from studies including youths with LPE/CU traits, ED and aggression are also reviewed, as response moderators.

EXPERT OPINION

Due to its clinical heterogeneity, relevant subtypes of CD should be carefully characterized to gain reliable information on prognosis and treatments. Thus, disentangling this broad category in subtypes is crucial as a first step in diagnosis. Psychosocial interventions are the first option, possibly improving LPE/CU traits and ED, especially if implemented early during development. Instead, limited information, based on low-quality studies, supports pharmacological options. Second-generation antipsychotics, mood stabilizers, and stimulants are first-line medications, according to different target symptoms, such as aggression and emotional reactivity. Developmental pathways including ADHD suggest a specific role of psychostimulants.

Examining attention-deficit/hyperactivity disorder and related behavioral disorders by fertility treatment exposure in a prospective cohort

PURPOSE

To evaluate whether underlying infertility and mode of conception are associated with childhood behavioral disorders.

METHODS

Oversampling on fertility treatment exposure using vital records, the Upstate KIDS Study followed 2057 children (of 1754 mothers) from birth to 11 years. Type of fertility treatment and time to pregnancy (TTP) were self-reported. Mothers completed annual questionnaires reporting symptomology, diagnoses, and medications at 7-11 years of age. The information identified children with probable attention-deficit/hyperactivity disorder, anxiety or depression, and conduct or oppositional defiant disorders. We estimated adjusted relative risks (aRR) for disorders by underlying infertility (TTP > 12 months) or treatment exposure groups compared to children born to parents with TTP ≤ 12 months.

RESULTS

Children conceived with fertility treatment (34%) did not have an increased risk of attention-deficit/hyperactivity disorder (aRR): 1.21; 95% CI: 0.88, 1.65), or conduct or oppositional defiant disorders (aRR: 1.31; 0.91, 1.86), but did have an increased risk of anxiety or depression (aRR: 1.63; 1.18, 2.24), which remained elevated even after adjusting for parental mood disorders (aRR: 1.40; 0.99, 1.96). Underlying infertility without the use of treatment was also associated with a risk of anxiety or depression (aRR: 1.82; 95% CI: 0.96, 3.43).

CONCLUSIONS

Underlying infertility or its treatment was not associated with risk of attention-deficit/hyperactivity disorder. Observations of increased anxiety or depression require replication.

Machine Learning-Based Aggression Detection in Children with ADHD Using Sensor-Based Physical Activity Monitoring

Aggression in children is highly prevalent and can have devastating consequences, yet there is currently no objective method to track its frequency in daily life. This study aims to investigate the use of wearable-sensor-derived physical activity data and machine learning to objectively identify physical-aggressive incidents in children. Participants (n = 39) aged 7 to 16 years, with and without ADHD, wore a waist-worn activity monitor (ActiGraph, GT3X+) for up to one week, three times over 12 months, while demographic, anthropometric, and clinical data were collected. Machine learning techniques, specifically random forest, were used to analyze patterns that identify physical-aggressive incident with 1-min time resolution. A total of 119 aggression episodes, lasting 7.3 ± 13.1 min for a total of 872 1-min epochs including 132 physical aggression epochs, were collected. The model achieved high precision (80.2%), accuracy (82.0%), recall (85.0%), F1 score (82.4%), and area under the curve (89.3%) to distinguish physical aggression epochs. The sensor-derived feature of vector magnitude (faster triaxial acceleration) was the second contributing feature in the model, and significantly distinguished aggression and non-aggression epochs. If validated in larger samples, this model could provide a practical and efficient solution for remotely detecting and managing aggressive incidents in children.

Pharmacological strategies for the management of the antisocial personality disorder

INTRODUCTION

Antisocial personality disorder (AsPD) is a pervasive pattern of violation of others' rights, related to the concept of psychopathy. AsPD is stable over time from adolescence, with evidence of conduct disorder (CD) before 15 years. DSM-5 included a specifier 'with limited prosocial emotions' (LPE), which characterizes adolescents with higher developmental vulnerability to develop AsPD. Despite being relatively frequent with considerable societal impact, AsPD is a difficult-to-treat condition with high comorbidity rates and poor evidence for effective pharmacological interventions.

AREAS COVERED

We conducted a narrative review and searched PubMed up to September 2022. We included RCTs and naturalistic studies evaluating pharmacological interventions on AsPD in adults, including those with comorbid substance use disorder or psychopathic traits. Evidence in youths with CD, callous-unemotional (CU) traits and aggression were also reviewed, exploring the role of CU traits as moderators of response.

EXPERT OPINION

Psychosocial interventions are the first option, with possible improvement of CU traits, beyond behavioral and affective symptoms, particularly if implemented early during development. Limited information, based on low-quality studies, supports the pharmacological options. Second-generation antipsychotics, lithium, anti-epileptic drugs, and stimulants are first-line medications, according to different target symptoms. Developmental pathways including ADHD suggest a specific role of psychostimulants.

Comorbidities in Youth with Bipolar Disorder: Clinical Features and Pharmacological Management

BACKGROUND

Bipolar Disorder (BD) is a highly comorbid condition, and rates of cooccurring disorders are even higher in youth. Comorbid disorders strongly affect clinical presentation, natural course, prognosis, and treatment.

METHODS

This review focuses on the clinical and treatment implications of the comorbidity between BD and Attention-Deficit/Hyperactivity Disorder, disruptive behavior disorders (Oppositional Defiant Disorder and/or Conduct Disorder), alcohol and substance use disorders, Autism Spectrum Disorder, anxiety disorders, Obsessive-Compulsive Disorder, and eating disorders.

RESULTS

These associations define specific conditions which are not simply a sum of different clinical pictures, but occur as distinct and complex combinations with specific developmental pathways over time and selective therapeutic requirements. Pharmacological treatments can improve these clinical pictures by addressing the comorbid conditions, though the same treatments may also worsen BD by inducing manic or depressive switches.

CONCLUSION

The timely identification of BD comorbidities may have relevant clinical implications in terms of symptomatology, course, treatment and outcome. Specific studies addressing the pharmacological management of BD and comorbidities are still scarce, and information is particularly lacking in children and adolescents; for this reason, the present review also included studies conducted on adult samples. Developmentally-sensitive controlled clinical trials are thus warranted to improve the prognosis of these highly complex patients, requiring timely and finely personalized therapies.

Predicting delinquent behavior in young adults with a childhood diagnosis of ADHD: results from the Cologne Adaptive Multimodal Treatment (CAMT) Study

The aim of this study was to investigate which factors predict lifetime reports of delinquent behavior in young adults who had received adaptive multimodal treatment of attention-deficit/hyperactivity disorder (ADHD) starting at ages 6-10 years. Participants were reassessed 13-24 years (M = 17.6, SD = 1.8) after they had received individualized ADHD treatment in the Cologne Adaptive Multimodal Treatment Study (CAMT). Their behavior was classified as non-delinquent (n = 34) or delinquent (n = 25) based on self-reports regarding the number of police contacts, offenses, and convictions at follow-up. Childhood variables assessed at post-intervention (e.g., externalizing child behavior problems, intelligence, and parenting behavior) that were significantly associated with group membership were entered as possible predictors of delinquency in a Chi-squared automatic interaction detector (CHAID) analysis. Delinquent behavior during adolescence and adulthood was best predicted by (a) meeting the symptom count diagnostic criteria for conduct disorder (CD) according to parent ratings, in combination with a nonverbal intelligence of IQ ≤ 106 at post-intervention, and (b) delinquent behavior problems (teacher rating) at post-intervention. The predictor variables specified in the CHAID analysis classified 81% of the participants correctly. The results support the hypothesis that a childhood diagnosis of ADHD is only predictive of delinquent behavior if it is accompanied by early conduct behavior problems. Low nonverbal intelligence was found to be an additional risk factor. These findings underline the importance of providing behavioral interventions that focus on externalizing behavior problems to children with ADHD and comorbid conduct problems.

Management of Emotion Dysregulation and Outbursts in Children and Adolescents

PURPOSE OF REVIEW

Emotion dysregulation and outbursts are very common reasons for referral to child and adolescent mental health services and a frequent cause of admission to hospitals and residential programs. Symptoms of emotion dysregulation and outburst are transdiagnostic, associated with many disorders, have the potential to cause severe impairment and their management presents a major challenge in clinical practice.

RECENT FINDINGS

There are an increasing number of psychosocial interventions that demonstrate promise in improving emotion dysregulation and outbursts. Acute care systems to manage the most severely ill patients have limited best practice guidelines but program advancements indicate opportunities to improve care models. Pharmacotherapy may be of assistance to psychosocial interventions but must be used with caution due to potential adverse effects. Much remains to be discovered however evidence informed, targeted treatments for specific populations show potential for future improvements in outcomes.

Neuropsychological Characterization of Aggressive Behavior in Children and Adolescents with CD/ODD and Effects of Single Doses of Medications: The Protocol of the Matrics_WP6-1 Study

Aggressive behaviors and disruptive/conduct disorders are some of the commonest reasons for referral to youth mental health services; nevertheless, the efficacy of therapeutic interventions in real-world clinical practice remains unclear. In order to define more appropriate targets for innovative pharmacological therapies for disruptive/conduct disorders, the European Commission within the Seventh Framework Programme (FP7) funded the MATRICS project (Multidisciplinary Approaches to Translational Research in Conduct Syndromes) to identify neural, genetic, and molecular factors underpinning the pathogenesis of aggression/antisocial behavior in preclinical models and clinical samples. Within the program, a multicentre case-control study, followed by a single-blind, placebo-controlled, cross-over, randomized acute single-dose medication challenge, was conducted at two Italian sites. Aggressive children and adolescents with conduct disorder (CD) or oppositional defiant disorder (ODD) were compared to the same age (10–17 y) typically developing controls (TDC) on a neuropsychological tasks battery that included both “cold” (e.g., inhibitory control, decision making) and “hot” executive functions (e.g., moral judgment, emotion processing, risk assessment). Selected autonomic measures (heart rate variability, skin conductance, salivary cortisol) were recorded before/during/after neuropsychological testing sessions. The acute response to different drugs (methylphenidate/atomoxetine, risperidone/aripiprazole, or placebo) was also examined in the ODD/CD cohort in order to identify potential neuropsychological/physiological mechanisms underlying aggression. The paper describes the protocol of the clinical MATRICS WP6-1 study, its rationale, the specific outcome measures, and their implications for a precision medicine approach.

Cold-Blooded and on Purpose: A Review of the Biology of Proactive Aggression

Proactive aggression (PA) is a planned and unprovoked form of aggression that is most often enacted for personal gain or in anticipation of a reward. Frequently described as "cold-blooded" or goal oriented, PA is thought to be associated with low autonomic arousal. With this view in mind, we performed a scoping review of the biological correlates of PA and identified 74 relevant articles. Physiological findings indicated a robust association between PA and reduced resting heart rate, and to a lesser extent a relationship between PA and decreased heart rate and skin conductance reactivity, perhaps indicating dampened sympathetic function. The twin literature identified PA as a heritable trait, but little evidence implicates specific genes in the pathogenesis of PA. Neuroimaging studies of PA pinpoint impaired amygdala function in the assessment and conditioning of aversive stimuli, which may influence the establishment of behavioral patterns. Nodes of the default mode network were identified as possible neural correlates of PA, suggesting that altered function of this network may be involved in the genesis of PA. Given the overlap of PA with reactive aggression and the overall behavioral complexity of PA, it is clear that multiple endophenotypes of PA exist. This comprehensive review surveys the most salient neurobiologically informed research on PA.

Neural Responses to Fluoxetine in Youths with Disruptive Behavior and Trauma Exposure: A Pilot Study

Objective: A preliminary investigation of the impact of a serotonergic agent (fluoxetine) on symptom profile and neural response in youths with disruptive behavior disorders (DBDs) and a history of trauma exposure. Methods: There were three participant groups: (i) Youths with DBDs and trauma exposure who received fluoxetine treatment for 8 weeks (n = 11); (ii) A matched group of youths with DBDs and trauma exposure who received routine regular follow-up in an outpatient clinic (n = 10); and (iii) Typically developing youths (n = 18). All participants conducted an expression processing functional magnetic resonance imaging task twice, 8 weeks apart: (pretreatment and post-treatment for youths with DBDs). Results: Youths with DBDs and trauma exposure who received fluoxetine treatment compared to the other two groups showed: (i) significant improvement in externalizing, oppositional defiant disorder, irritability, anxiety-depression, and trauma-related symptoms; (ii) as a function of fearful expression intensity, significantly decreased amygdala response and increased recruitment of regions implicated in top-down attention control (insula cortex, inferior parietal lobule, and postcentral gyrus) and emotional regulation (ventromedial prefrontal cortex [vmPFC]); and (iii) correlation between DBD/irritability symptom improvement and increased activation of top-down attention control areas (inferior parietal lobule, insula cortex, and postcentral gyrus) and an emotion regulation area (vmPFC). Conclusions: This study provides preliminary evidence that a serotonergic agent (fluoxetine) can reduce disruptive behavior and mood symptoms in youths with DBDs and trauma exposure and that this may be mediated by enhanced activation of top-down attention control and emotion regulation areas (inferior parietal lobule, insula cortex, and vmPFC).

Psychopharmacology of Treating Explosive Behavior

Explosive and aggressive behavior in children can pose safety risks, disturb family functioning, and lead to significant impairments. Pharmacologic management should be based on the first-line treatment of the primary psychiatric diagnoses of the patient and initiated in combination with appropriate psychosocial interventions. Review of the literature suggests that risperidone has the most supporting evidence in the treatment of explosive behavior. Stimulants have been shown to be helpful in the treatment of explosive behavior in attention-deficit/hyperactivity disorder. Medication treatment can be associated with significant side effects and therefore the risks and benefits of medication management must be weighed carefully.

Understanding Chronic Aggression and Its Treatment in Children and Adolescents

PURPOSE OF REVIEW

Youth aggression is common and has a significant burden on individuals, families, and society. However, its treatment is often a challenge for clinicians. Thus, this review will examine the current understanding of youth aggression, conceptualize aggression as a symptom rather than its own disorder, and provide an overview of treatment strategies.

RECENT FINDINGS

Youth aggression is associated with complex genetic, neurobiological, and environmental risks. Prevention strategies are of the utmost importance for at-risk families and youth. Psychosocial interventions are the first line treatment. But if not fully effective, then pharmacologic interventions-including psychostimulants, alpha-2 agonists, atomoxetine, and risperidone-have shown benefits. Other medications, such as SSRIs, can be useful in certain scenarios. It is important to conceptualize youth aggression as being a trans-diagnostic symptom in psychopathology. Determining the underlying cause of aggression will help to guide treatment.

Methylphenidate administration promotes sociability and reduces aggression in a mouse model of callousness

RATIONALE

Deficits in empathy constitute a distinctive feature of several psychopathologies, including conduct disorder (CD). The co-occurrence of callous-unemotional (CU) traits, excess rates of aggression and violation of societal norms confers specific risk for adult psychopathy. To date, the off-label use of methylphenidate (MPH) constitutes the drug treatment of choice.

OBJECTIVES

Herein, we tested the therapeutic potential of MPH in a recently devised mouse model recapitulating the core phenotypic abnormalities of CD.

METHODS

Two subgroups of BALB/cJ male mice exhibiting opposite profiles of emotional contagion (i.e. socially transmitted adoption of another's emotional states) were investigated for reactive aggression, sociability, attention control, anxiety-related behaviours and locomotor activity, in response to MPH administration (0.0, 3.0 or 6.0 mg/kg).

RESULTS

Our data indicate that mice selected for excess callousness exhibit phenotypic abnormalities isomorphic to the symptoms of CD: stability of the low emotional contagion trait, increased aggression and reduced sociability. In accordance with our predictions, MPH reduced aggression and increased sociability in callous mice; yet, it failed to restore the low responsiveness to the emotions of a conspecific in pain, isomorphic to CU traits.

CONCLUSIONS

Although our data support the notion that MPH may contribute to the management of excess aggression in CD patients, additional studies shall identify specific treatments to target the callousness domain. The latter, unaffected by MPH in our experimental model, demands focused consideration whereby it constitutes a specifier associated with a worse prognosis.

Amygdala and Hypothalamus: Historical Overview With Focus on Aggression

Aggressiveness has a high prevalence in psychiatric patients and is a major health problem. Two brain areas involved in the neural network of aggressive behavior are the amygdala and the hypothalamus. While pharmacological treatments are effective in most patients, some do not properly respond to conventional therapies and are considered medically refractory. In this population, surgical procedures (ie, stereotactic lesions and deep brain stimulation) have been performed in an attempt to improve symptomatology and quality of life. Clinical results obtained after surgery are difficult to interpret, and the mechanisms responsible for postoperative reductions in aggressive behavior are unknown. We review the rationale and neurobiological characteristics that may help to explain why functional neurosurgery has been proposed to control aggressive behavior.

The evidence-based choice for antipsychotics in children and adolescents should be guaranteed

PURPOSE

Drug use in the pediatric population still often features off-label prescriptions, particularly for psychotropic drugs. We reviewed the registration status, scientific evidence, and recommendations from the guidelines for antipsychotics used for psychiatric disorders in children.

METHODS

Antipsychotic drugs marketed in Italy, the United Kingdom (UK) and United States (US) were identified with the ATC Classification System. The licensing status and Summary of Product Characteristics (SPC) were taken from the national formularies. We analyzed reviews and guidelines on antipsychotics use in children and adolescents in the MEDLINE, EMBASE, and PsycINFO databases.

RESULTS

Out of 67 drugs, 19 were marketed with a pediatric license in at least one country: three in all the selected countries, and only paliperidone with the same indications. Haloperidol was the only antipsychotic authorized for autism in Italy and the UK, and as well as risperidone and aripiprazole in the US. Aripiprazole and paliperidone were licensed in all three countries for schizophrenia. Aripiprazole was licensed for bipolar disorders in all three countries. Haloperidol was licensed for Tourette syndrome in Italy and the UK, and pimozide and aripiprazole in the US. We retrieved 21 pertinent reviews and 13 guidelines for the management of neuropsychiatric disorders in pediatrics. There was a complete overlap between the authorized therapeutic indications and the available scientific evidence for autism in the US, for conduct disorders and bipolar disorders in the UK, and for Tourette syndrome and tics in the UK and Italy.

CONCLUSIONS

These results highlight the different regulatory processes that deny to many children and adolescents the most appropriate and rational antipsychotic therapy.

Methylphenidate Dose-Dependently Affects Aggression and Improves Fear Extinction and Anxiety in BALB/cJ Mice

Overt aggression, increased anxiety, and dysfunctional fear processing are often observed in individuals with conduct disorder (CD) and attention-deficit hyperactivity disorder (ADHD). Methylphenidate (MPH), a psychostimulant increasing dopamine and noradrenaline tone, is effective in reducing aggression in both CD and ADHD individuals. However, it is unclear to which extent these effects of MPH are dose dependent. Here, the effects of acute intraperitoneal MPH (3 and 10 mg/kg) on aggression, anxiety, social behavior, and fear extinction were investigated in BALB/cJ mice. Previous studies in BALB/cJ mice have revealed high levels of aggression and anxiety that are associated with reduced top-down cortical control. Administration of 3 mg/kg MPH prolonged the attack latency and prevented escalation of aggression over time compared to vehicle-treated mice, while 10 mg/kg MPH increased number of bites and attacks. In addition, 3 mg/kg MPH decreased social interaction slightly. A strong anxiolytic effect was found after administration of both the 3 and 10 mg/kg doses in the elevated plus maze and the open-field test. In addition, while vehicle-treated BALB/cJ animals showed intact freezing, both doses of MPH decreased freezing to the unconditioned stimulus in a fear-conditioning paradigm. A long-lasting effect on fear extinction was visible after treatment with the 10 mg/kg dose. The data support a role for MPH in the regulation of anxiety, fear processing, and aggression in BALB/cJ mice, with the latter effect in a dose-dependent manner. The findings provide a further context for examining the effects of MPH in clinical disorders such as ADHD and CD.

Examining predictors of initial outpatient psychiatric treatment for conduct problems in youth: A records review

PURPOSE

To investigate predictors of conduct problem (CP) treatment in an outpatient child psychiatry clinic.

DESIGN AND METHODS

Medical records (N = 78) of youth with CPs (71% male; mean age = 9.9 years) were analyzed to determine how treatment history, race, gender, travel distance, aggression symptoms, internalizing disorder symptoms, and age of diagnosis influenced initial treatment decisions.

FINDINGS

Severity of aggression symptoms and travel distance significantly increased the likelihood that initial treatments included psychotropic medication. Travel distance also moderated the relationship between history of psychosocial intervention for CPs and treatment recommendations.

PRACTICE IMPLICATIONS

Adhering to treatment guidelines for youth with CPs is essential for furthering evidence-based psychiatric nursing care.

Conduct disorders and psychopathy in children and adolescents: aetiology, clinical presentation and treatment strategies of callous-unemotional traits

Conduct Disorder (CD) is a psychiatric diagnosis characterized by a repetitive and persistent pattern of behaviour in which the basic rights of others and major age-appropriate social norms or rules are violated. Callous Unemotional (CU) traits are a meaningful specifier in subtyping CD for more severe antisocial and aggressive behaviours in adult psychopathology; they represent the affective dimension of adult psychopathy, but they can be also detected in childhood and adolescence. The CU traits include lack of empathy, sense of guilt and shallow emotion, and their characterization in youth can improve our diagnostic, prognostic and therapeutic abilities. A strong genetic liability, in interaction with parenting and relevant environmental factors, can lead to elevated levels of CU traits in children. We pointed out that CU traits can be detected in early childhood, may remain stable along the adolescence, but a decrease following intensive and specialized treatment is possible. We here provide a narrative review of the available evidences on CU traits in three main domains: aetiology (encompassing genetic liability and environmental risk factors), presentation (early signs and longitudinal trajectories) and treatments.