Impulsivity as key bridge symptoms in cross-sectional and longitudinal networks of ADHD and ODD.

BACKGROUND: Impulsivity is viewed as key to attention-deficit/hyperactivity disorder (ADHD) and disruptive behavior disorders (DBD). Yet, to date, no work has provided an item-level analysis in longitudinal samples across the critical developmental period from childhood into adolescence, despite prior work suggesting items exhibit differential relevance with respect to various types of impairment. The current study conducted a novel longitudinal network analysis of ADHD and oppositional defiant disorder (ODD) symptoms between childhood and adolescence, with the important applied prediction of social skills in adolescence. METHODS: Participants were 310 children over-recruited for clinical ADHD issues followed longitudinally for six years in total with gold standard diagnostic procedures and parent and teacher ratings of symptoms and social outcomes. RESULTS: Findings from baseline, Year 3, and Year 6 suggested Difficulty waiting turn, Blurts, and Interrupts/intrudes were key bridge items across cross-sectional and longitudinal parent-reported DBD networks. Furthermore, shortened symptom lists incorporating these symptoms were stronger predictors of teacher-rated social skills 5 years later compared to total DBD scores. CONCLUSIONS: Such findings are consistent with the trait impulsivity theory of DBD and ADHD and may inform useful screening tools and personalized intervention targets for children at risk for DBD during adolescence.

Attention-deficit/hyperactivity disorder and the menstrual cycle: Theory and evidence.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that exhibits striking sex differences in symptoms, prevalence, and associated problems across development. Etiological factors and mechanisms underlying these sex differences remain one of the most understudied aspects of this disorder. The current paper seeks to provide a novel theoretical framework for understanding this phenomenon by reviewing evidence that females with ADHD may experience a "double whammy" of organizational and activational pubertal hormonal effects. We propose a novel theory of activational effects of cyclical circulating ovarian hormones on ADHD with increasing risk at times of rapid declines in estrogen. These declines may decrease executive function and trait control at two points of the cycle characterized by biphasic affective risk: (1) increases in approach/risk-taking behaviors at mid-cycle (periovulatory) and (2) increases in avoidance/negative affect perimenstrually. Low estrogen and control may then interact with increases in positive and negative affect, respectively, to increase hyperactivity-impulsivity symptoms post-ovulation and inattention symptoms perimenstrually. These interactions may be exacerbated by organizational pubertal effects on relatively overdeveloped limbic circuitry and adolescent-specific social pressures magnified in females with ADHD.

Evidence-Based Assessment for Attention-Deficit/Hyperactivity Disorder.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects individuals from all life stages, genders, and races/ethnicities. Accurate assessment of ADHD across different populations is essential as undiagnosed ADHD is associated with numerous costly negative public health outcomes and is complicated by high comorbidity and developmental change in symptoms over time. Predictive analysis suggests that best-practice evidence-based assessment of ADHD should include both ADHD-specific and broadband rating scales from multiple informants with consideration of IQ, academic achievement, and executive function when there are concerns about learning. For children under age 12, parent and teacher ratings should be averaged. For adolescents and adults, informant reports should be prioritized when self- and other-report are inconsistent. Future research should provide more stringent evaluation of the sensitivity of measures to treatment response and developmental change over time as well as further validate measures on historically understudied populations (i.e., adults, women, and racial/ethnic minorities).

Evidence-Based Assessment of Developmental Disorders.

Developmental disorders are diverse, common, and impairing; still, many clinicians lack comprehensive training in their assessment. This review presents thorough guidelines for the evaluation and diagnosis of common communication, sleeping, feeding, and elimination disorders that often onset in the early developmental period and that are commonly encountered in clinical practice. Thorough guidance on the evidence-based assessment of developmental disorders is critical, as they are prevalent, impairing, and commonly comorbid with other psychiatric disorders of childhood. This review is the first of its kind-providing critically needed, step-by-step guidance on the existing evidence-based methodologies and assessment tools available for diagnosis. This review also makes clear the dire need for further development and validation of relevant screening and diagnostic measure and calls for specific attention to the development of specific screening and diagnostic assessment measures for feeding disorders and elimination disorders in particular. Clinicians and researchers alike may find this article useful in guiding diagnostic, treatment, and research procedures.

Effect of menstrual cycle on rewarding properties of alcohol cues in women.

OBJECTIVE: Compared with men, women are disproportionately affected by alcohol, including greater risks of behavioral impairment and relapse from abstinence-based treatments. One potential mechanism underlying this disparity is ovarian hormone fluctuations across menstrual cycle phases, particularly estradiol (E2). Preclinical and clinical studies have shown that E2 levels positively correlate with alcohol consumption, suggesting E2 modulates drinking. Rewarding properties of alcohol are thought to mediate this relationship. The present study tested the degree to which women report increased rewarding effects from alcohol and heightened attention to alcohol-related cues when E2 was elevated during the late follicular phase of the menstrual cycle. METHOD: Fifty women aged 21-29 participated in a within-subjects placebo-controlled study examining how menstrual cycle phase alters the rewarding properties of alcohol and alcohol-associated cues when sober and intoxicated, as measured by their attentional bias toward alcohol-associated cues and subjective reports. Measures were obtained following 0.60 g/kg alcohol and placebo during the early follicular phase when E2 was low and the late follicular phase (i.e., ovulation) when E2 was elevated. RESULTS: Attentional bias to alcohol-associated cues was greater during the late follicular phase in both sober and intoxicated states. Women reported rewarding effects from alcohol, but no effects of phase were observed. CONCLUSIONS: The findings suggest that the rewarding properties of alcohol-associated cues might be enhanced during the late follicular phase of the menstrual cycle when E2 is elevated, possibly increasing the risk for excessive drinking in women during this phase. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A Network Analysis of Executive Functions in Children and Adolescents With and Without Attention-Deficit/Hyperactivity Disorder.

This study applied network analysis to executive function test performances to examine differences in network parameters between demographically matched children and adolescents with and without attention-deficit/hyperactivity disorder (ADHD) (n = 141 per group; M = 12.7 ± 2.9 years-old; 72.3% boys, 66.7% White, 65.2% ≥ 12 years maternal education). All participants completed the NIH Toolbox Cognition Battery, including the Flanker, measuring inhibition, Dimensional Change Card Sort, measuring shifting, and List Sorting test, measuring working memory. Children with and without ADHD had comparable mean test performances (d range: .05-0.11) but presented with differences in network parameters. Among participants with ADHD, shifting was less central, had a weaker relationship with inhibition, and did not mediate the relationship between inhibition and working memory. These network characteristics were consistent with the executive function network structure of younger ages in prior research and may reflect an immature executive function network among children and adolescents with ADHD, aligning with the delayed maturation hypothesis.

The Oregon ADHD-1000: A new longitudinal data resource enriched for clinical cases and multiple levels of analysis.

The fields of developmental psychopathology, developmental neuroscience, and behavioral genetics are increasingly moving toward a data sharing model to improve reproducibility, robustness, and generalizability of findings. This approach is particularly critical for understanding attention-deficit/hyperactivity disorder (ADHD), which has unique public health importance given its early onset, high prevalence, individual variability, and causal association with co-occurring and later developing problems. A further priority concerns multi-disciplinary/multi-method datasets that can span different units of analysis. Here, we describe a public dataset using a case-control design for ADHD that includes: multi-method, multi-measure, multi-informant, multi-trait data, and multi-clinician evaluation and phenotyping. It spans > 12 years of annual follow-up with a lag longitudinal design allowing age-based analyses spanning age 7-19 + years with a full age range from 7 to 21. Measures span genetic and epigenetic (DNA methylation) array data; EEG, functional and structural MRI neuroimaging; and psychophysiological, psychosocial, clinical and functional outcomes data. The resource also benefits from an autism spectrum disorder add-on cohort and a cross sectional case-control ADHD cohort from a different geographical region for replication and generalizability. Datasets allowing for integration from genes to nervous system to behavior represent the "next generation" of researchable cohorts for ADHD and developmental psychopathology.

Data-Driven Methods for Predicting ADHD Diagnosis and Related Impairment: The Potential of a Machine Learning Approach.

Current diagnostic criteria for ADHD include several symptoms that highly overlap in conceptual meaning and interpretation. Additionally, inadequate sensitivity and specificity of current screening tools have hampered clinicians' ability to identify those at risk for related outcomes. Using machine learning techniques, the current study aimed to propose a novel algorithm incorporating key ADHD symptoms to predict concurrent and future (i.e., five years later) ADHD diagnosis and related impairment levels. Participants were 399 children with and without ADHD; multiple informant measures of ADHD symptoms, global impairment, academic performance, and social skills were included as part of an accelerated longitudinal design. Results suggested eight symptoms as most important in predicting impairment outcomes five years later: (1) Has difficulty sustaining attention in tasks or play activities, (2) Does not follow through on instructions and fails to finish work, (3) Has difficulty organizing tasks and activities, (4) Avoids tasks (e.g., schoolwork, homework) that require sustained mental effort, (5) Is often easily distracted, (6) Is often forgetful in daily activities, (7) Fidgets with hands or feet or squirms in seat, and (8) Interrupts/intrudes on others. The algorithm comprising this abbreviated list of symptoms performed just as well as or significantly better than one comprising all 18 symptoms in predicting future global impairment and academic performance, but not social skills. It also predicted concurrent and future ADHD diagnosis with 81-93% accuracy. Continued development of screening tools will be key to ensuring access to clinical services for youth at risk for ADHD.

Aging and Pubertal Development Differentially Predict Symptoms of ADHD, Depression, and Impairment in Children and Adolescents: An Eight-Year Longitudinal Study.

Activational effects of the reproductive neuroendocrine system may explain why some youths with ADHD are at greater risk for exacerbated ADHD symptoms (hyperactivity, inattention, impulsivity) during adolescence. For youths diagnosed with ADHD, first signs of ADHD symptoms become noticeable by multiple reporters (e.g., teachers, parents) when children enter schools, typically around kindergarten. The current study examined possible sex differences in ADHD, impairment, and comorbidity due to pubertal effects, as the role of pubertal development in ADHD is understudied. ADHD symptoms, depressive symptoms, impairment, and pubertal stage were assessed annually by multiple reporters in a well-characterized community sample of 849 children over-recruited for ADHD over eight years. Ages ranged from 7 to 13 years (38.16% female) at wave 1. Multilevel models indicated that males had higher levels of hyperactivity, impulsivity, and inattention than females, but that females had higher levels of impairment than males. Inattention symptoms did not show marked maturation changes. Hyperactivity and impulsivity declined as youth aged and impairment increased as youth aged. Lastly, depressive symptoms largely increased as youth aged and were higher amongst youth at later pubertal stages. Put together, aging and pubertal development are associated with improved ADHD symptoms but not for youth with high impairment. Findings from this study contributes to understanding the role that aging, pubertal status, and pubertal development plays in ADHD, impairment, and comorbidity in children and adolescents.

Heightened sensitivity to the disinhibiting effect of alcohol in women during the late follicular phase of the menstrual cycle.

Compared with men, women are disproportionately affected by alcohol, including greater risks of physiological damage, behavioral impairment, and relapse. One likely mechanism underlying the sexual disparity in this vulnerability is the fluctuation of ovarian hormones, particularly estradiol (E2), across phases of the menstrual cycle. Several preclinical and clinical studies have shown that higher E2 levels positively correlate with drinking, suggesting E2 may play a significant role in modulating drinking. Inhibitory control also modulates drinking; when it is reduced or compromised by alcohol, the drinker's ability to stop the self-administration of alcohol could be impaired, leading to a binge episode. The present study aimed to examine the degree to which menstrual cycle phase can influence the disinhibiting effect of alcohol. Twenty-four healthy young adult women participated in a within-subjects placebo-controlled study of the acute disinhibiting effect of 0.60 g/kg alcohol over the course of two test sessions. A cued go/no-go task measured the disinhibiting effects of alcohol and placebo beverages during the early follicular phase of the cycle when E2 levels were low and the late follicular phase (i.e., ovulation) when E2 was elevated. Results showed that the disinhibiting effect of alcohol increased nearly twofold during the late follicular phase when E2 was elevated. These findings highlight the role of alcohol-induced disinhibition as a potential behavioral mechanism by which fluctuations in ovarian hormones as a function of the menstrual cycle contribute to increased risk for excessive alcohol use in women. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Clarifying Relations Between ADHD and Functional Impairment in Adulthood: Utilization of Network and Machine Learning Approaches.

Using network analysis and random forest regression, this study identified attention-deficit/hyperactivity disorder (ADHD) symptoms most important for indicating impairment in various functional domains. Participants comprised a nationally representative sample of 1249 adults in the United States. Bridge symptoms were identified as those demonstrating unique relations with impairment domains that, in total, were stronger than those involving other symptoms. Results suggested three inattentive (i.e., difficulty organizing; does not follow through; makes careless mistakes) and one hyperactive (difficulty engaging in leisure activities) bridge symptoms. Random forest regression results supported bridge symptoms as most important (compared to other symptoms) for predicting global and specific impairment domains. Hyperactive/impulsive symptoms appeared more strongly related to impairment in women, whereas difficulty organizing and easily distracted appeared more related to impairment in men. Clarification of bridge symptoms may help identify core characteristics of ADHD in adulthood and specify screening and intervention targets to reduce risk for related impairment.

Utility of the Limited Prosocial Emotions Specifier in Preschoolers With Conduct Problems.

This study examined the clinical utility of the "Limited Prosocial Emotions" (LPE) specifier (i.e., prevalence rates, group differences, and predictive utility) in a high-risk preschool sample (N = 109, M age = 4.77) presenting with conduct problems (CPs; n = 59). First, LPE prevalence rates ranged from 7.7% to 89.8%. Next, few group differences were observed between with CP-only and CP+LPE; youth with CP+LPE differed from youth with CP-only on callous-unemotional (CU) traits and verbal ability, but not on externalizing or internalizing psychopathology, nor on parenting experiences. In the full sample, youth with LPE differed from youth without LPE on externalizing and internalizing psychopathology, parenting, and verbal ability. Finally, LPE predicted greater baseline CP but did not predict trajectories of CP. Findings highlight the clinical utility of the LPE specifier during early childhood and call for a refinement of the LPE specifier to improve its clinical value.

Etiological Networks of Attention-Deficit/Hyperactivity Disorder during Childhood and Adolescence.

OBJECTIVE: The purpose of the current study was to use network analysis techniques to parse relations between attention-deficit/hyperactivity disorder (ADHD) symptom domains, domains of executive function, and temperament traits. METHODS: Participants were 420 children aged 6-17 years (55% boys). The majority of the participants were Caucasian (72.86%) and 50% of the sample met diagnostic criteria for ADHD. Both parents and teachers provided ratings of participants' ADHD symptom severity. Parents completed questionnaires pertaining to participants' temperament traits, and participants completed well-validated laboratory measures of executive function. RESULTS: Results suggested effortful control as demonstrating the strongest relations with ADHD, particularly the parent-reported inattentive symptom domain. Additionally, negative effects appeared to demonstrate weaker but still notable relations primarily with the parent-reported hyperactive/impulsive symptom domain. Measures of executive function did not appear to demonstrate relations with any measures of ADHD symptoms or temperament traits. The results were generally replicated in a distinct sample (n = 732, 7-13 years, 63% boys, 81% White), although differences emerged pertaining to the role of surgency (i.e., related to the hyperactive/impulsive symptom domain in the replication but not the primary sample). CONCLUSIONS: Overall, findings provided support for the primary role of effortful control, as well as secondary roles for negative affect and surgency, as key risk markers for the characterization of ADHD. Additional exploration of the overlap between temperament and executive function, as pertaining to ADHD, may help clarify heterogeneity in phenotypes and suggest priorities for targeted interventions outside of traditional symptoms.

The unity and diversity of executive functions: A network approach to life span development.

As a novel approach to conceptualizing executive functions, this study applied network analysis to a common battery of executive function tests administered to a sample covering the life span. Participants (N = 3,944; age: M = 20.8 years, SD = 19.6, range: 3-85; maternal/self education: M = 12.9 years, SD = 2.6; 53.3% girls/women, 46.7% boys/men; 61.1% White, 18.2% African American, 14.0% Latinx, 6.8% other races/ethnicities) completed tests of inhibition, shifting, and updating/working memory. Zero-order and partial correlation network models were calculated for divided age groups, with network parameters compared between groups: edge weights, corresponding to zero-order or partial correlations between two executive functions; expected influence, quantifying centrality; and global strength, quantifying differentiation. Executive functions differentiated from childhood to adolescence and dedifferentiated during young adulthood, with further dedifferentiation at older adulthood. Shifting emerged as more central than other abilities in adolescence and adulthood versus childhood, with a mediational role of shifting between inhibition and updating/working memory. A network approach can appropriately capture the unity and diversity of executive functions, by which unity reflects the reciprocal engagement between diverse abilities to produce goal-directed behavior. The engagement between abilities, and a mediational role of shifting between inhibition and updating/working memory, may be necessary for the emergence of effective goal-directed behavior. Through a network approach, the unity of executive functions represents an emergent property of the dynamics between multiple abilities (e.g., inhibition, shifting, and updating/working memory) that, when working effectively in tandem, lead to integrative processes (e.g., problem solving) that contribute to successful executive behavior and goal attainment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Longitudinal Temperament Pathways to ADHD Between Childhood and Adolescence.

The current investigation extended prior cross-sectional mapping of etiological factors, transdiagnostic effortful and affective traits, and ADHD symptoms to longitudinal pathways extending from two etiological domains: polygenic and prenatal risk. Hypotheses were (1) genetic risk for ADHD would be related to inattentive ADHD symptoms in adolescence and mediated by childhood effortful control; (2) prenatal smoking would be related to hyperactive-impulsive ADHD symptoms during childhood and mediated by childhood surgency; and (3) there would be age-related variation, such that mediation of genetic risk would be larger for older than younger ages, whereas mediation of prenatal risk would be larger in earlier childhood than at later ages. Participants were 849 children drawn from the Oregon ADHD-1000 Cohort, which used a case control sample and an accelerated longitudinal design to track development from childhood (at year 1 ages 7-13) through adolescence (at year 6 ages 13-19). Results showed the mediational pathway from prenatal smoking through surgency to hyperactivity-impulsivity at Year 1 was significant (indirect effect estimate = .053, p < .01). The mediational pathway from polygenic risk through effortful control to inattention at Year 6 was also significant (indirect effect estimate = .084, p < .01). Both results were independent of the association between inattention and hyperactivity-impulsivity and control for the alternative etiological input and held across parent- and teacher-report of ADHD symptoms. In line with dual pathway models of ADHD, early prenatal risk for hyperactivity-impulsivity appears to operate through surgency, while polygenic genetic risk for inattention appears mediated by effortful control.

Parental Barriers in Seeking Mental Health Services for Attention Deficit Hyperactivity Disorder in Children: Systematic Review.

OBJECTIVE: Many children at risk for negative outcomes related to untreated attention deficit hyperactivity disorder (ADHD) do not receive necessary mental healthcare. Parents' mental health-seeking behavior is important in the early identification of ADHD and preventing comorbidities with ADHD. Parents may experience some barriers that may delay or stop parents from seeking mental healthcare for their children. METHOD: This systematic review summarized existing evidence of parents' barriers to seeking mental healthcare for their children at risk of ADHD. RESULTS: This review included 21 studies that address different parental barriers under the three levels of the social-ecological model, including individual, interpersonal, and community levels. CONCLUSION: Raising parents' awareness of the process of seeking mental healthcare has the potential to help identify children at risk for ADHD earlier. Developing psychoeducational intervention that improves parents' seeking behavior and reduces barriers toward seeking mental healthcare is needed.

Longitudinal attention-deficit/hyperactivity disorder symptom networks in childhood and adolescence: Key symptoms, stability, and predictive validity.

The current study visualized attention-deficit/hyperactivity disorder (ADHD) symptom networks in a longitudinal sample of participants across childhood and adolescence with exploratory examination of age and gender effects. Eight hundred thirty-six children ages 7-13 years were followed annually for 8 years in total. Across parent and teacher report, results suggested "is easily distracted" and "difficulties sustaining attention" as central symptoms across three testing points (i.e., Year 1, Year 3, and Years 5-8 collapsed). "Difficulties following instructions" and "intrudes/interrupts" also emerged as parent-reported central symptoms. Assessment of network structure across the three testing points suggested global robustness of relations among ADHD symptoms from midchildhood into early adolescence. However, relations among symptoms that cause problems in school settings (i.e., being easily distracted) were stronger in teacher-reported than parent-reported networks. When aggregated into a sum score, central symptoms during Year 1 predicted total difficulties related to mental health problems 5 years later just as well as all 18 symptoms. Central symptoms of ADHD may be useful as screeners of future emotional and behavioral difficulties. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Identifying the Inter-Domain Relations Among ODD, CD, and CU Traits in Preschool Children Using Network Analysis.

Oppositional defiant disorder (ODD) and conduct disorder (CD) are two of the most common forms of disruptive behavior disorders during childhood. Callous-unemotional (CU) traits are an important factor in understanding the presentation of these externalizing forms of psychopathology. ODD, CD, and CU traits are highly related constructs, yet little work has examined how these externalizing forms of psychopathology are related at the domain level. The current study utilized network analysis to identify the distinct domains that explain the associations among ODD, CD, and CU traits. In a sample of 104 preschoolers (M age = 4.76), results demonstrated that the symptom domains of (a) angry/irritable mood and argumentative/defiant behavior, (b) aggression to people and animals, and (c) callousness were the primary bridge domains for ODD, CD, and CU traits, respectively. Findings of the current study offer a more nuanced insight into the relations amongst ODD, CD, and CU traits. Identification of bridge symptom domains can inform intervention practices by targeting specific symptom domains that are contributing to the maintenance of such aggressive and disruptive behaviors.

Multiple informant average integration of ADHD symptom ratings predictive of concurrent and longitudinal impairment.

To date, there remains no consensus about the best evidence-based method for integrating multiple informant data in the diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD). Several approaches exist, including the psychometrically sound approach of averaging scores, as well as the use of "OR" and "AND" algorithms, which are still commonly used in research. The current study tested these major integration methods in their concurrent and longitudinal prediction of clinician-rated impairment, teacher-rated academic, and parent- and self-rated social skill ratings in children overrecruited for ADHD across a 6-year span from childhood to adolescence. The sample included a total of 800 children, 480 with ADHD, ages 6 to 13, who completed a "gold standard" assessment of ADHD and associated impairment. Overall, the "OR," "AND," and average integration approaches showed significantly high interrelations with one another (r range from .78 to .96) and were all significantly and strongly related to impairment measures concurrently and longitudinally. Multivariate regressions demonstrated that the average integration approach concurrently and longitudinally out predicted the other two approaches. Results demonstrated that the average approach slightly outperformed the other two in its prediction of concurrent and longitudinal clinician-rated impairment, teacher-rated academic skills, and parent- and self-rated child social skills across childhood and adolescence. Evidence-based assessment integration of parent and teacher ratings of ADHD in childhood might best utilize an averaging approach, as it is most related to later impairment ratings, particularly if such findings are replicated by other groups. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Longitudinal network model of the co-development of temperament, executive functioning, and psychopathology symptoms in youth with and without ADHD.

Attention Deficit Hyperactivity Disorder (ADHD) is a common, chronic, and impairing disorder, yet presentations of ADHD and clinical course are highly heterogeneous. Despite substantial research efforts, both (a) the secondary co-occurrence of ADHD and complicating additional clinical problems and (b) the developmental pathways leading toward or away from recovery through adolescence remain poorly understood. Resolving these requires accounting for transactional influences of a large number of features across development. Here, we applied a longitudinal cross-lagged panel network model to a multimodal, multilevel dataset in a well-characterized sample of 488 children (nADHD=296) to test Research Domain Criteria initiative-inspired hypotheses about transdiagnostic risk. Network features included DSM symptoms, trait-based ratings of emotional functioning (temperament), and performance-based measures of cognition. Results confirmed that ADHD symptom domains, temperamental Irritability, and Working Memory are independent transdiagnostic risk factors for psychopathology based on their direct associations with other features across time. ADHD symptoms and working memory each had direct, independent associations with depression. Results also demonstrated tightly linked co-development of ADHD symptoms and temperamental Irritability, consistent with the possibility that this type of anger dysregulation is a core feature that is co-expressed as part of the ADHD phenotype for some children.