Sexual and Dating Violence Prevention Programs for Male Youth: A Systematic Review of Program Characteristics, Intended Psychosexual Outcomes, and Effectiveness.

Sexual and dating violence (SDV) by male youth (≤ 25 years)-including sexual harassment, emotional partner violence, and rape-is a worldwide problem. The goal of this preregistered (PROSPERO, ID: CRD42022281220) systematic review was to map existing SDV prevention programs aimed at male youth, including their characteristics (e.g., content, intensity), intended psychosexual outcomes, and empirically demonstrated effectiveness, guided by the principles of the theory of planned behavior (TPB). We conducted searches in six online databases for published, peer-reviewed quantitative effectiveness studies on multi-session, group focused, and interaction based SDV prevention programs for male youth ending March 2022. After screening of 21,156 hits using PRISMA guidelines, 15 studies on 13 different programs, from four continents were included. Narrative analysis showed, first, broad ranges in program intensity (2-48 h total), and few program curricula included explicit discussion of relevant aspects of the TPB. Second, programs' main intended psychosexual outcomes were to change SDV experiences, or related attitudes, or norms. Third, significant effects were found mostly on longer term behaviors and short-term attitudes. Other theoretical proxies of SDV experiences, such as social norms and perceived behavioral control, were sparsely investigated; thus, program effectiveness on these outcomes remains largely unknown. Assessed with the Cochrane Risk of Bias Tool, moderate to serious risk of bias arose in all studies. We present concrete suggestions for program content, such as explicit attention to victimization and masculinity and discuss best practices for evaluation research, including assessments of program integrity, and examining relevant theoretical proxies of SDV.

Prenatal predictors of childhood anxiety disorders: An exploratory study of the role of attachment organization.

Childhood anxiety disorders (CAD) are a common childhood mental disorder and understanding early developmental pathways is key to prevention and early intervention. What is not understood is whether early life stress predictors of CAD might be both mediated by infant cortisol reactivity and moderated by infant attachment status. To address this question, this exploratory study draws on 190 women recruited in early pregnancy and followed together with their children until 4 years of age. Early life stress is operationalized as maternal depression measured using the Structured Clinical Interview for the DSM, Childhood Trauma Questionnaire, Parenting Stress Index, and antenatal maternal hair cortisol concentrations. Infant cortisol reactivity was measured at 12 months together with the Strange Situation Procedure and CAD assessed at 4 years of age using the Preschool Age Psychiatric Assessment. There was no direct association between attachment classification and CAD. Furthermore, infant cortisol reactivity neither mediated nor attachment moderated the association of early life stress predictors and CAD. However, only for infants with organized attachment classifications, higher maternal antenatal depression, and hair cortisol were associated with a higher risk of CAD.

Maternal trauma but not perinatal depression predicts infant-parent attachment.

Understanding if maternal depression is a predictor of infant-parent attachment classification is important to furthering knowledge about the early pathways and predictors of socio-emotional development. Yet few studies that have utilised the Strange Situation Procedure, the gold standard for measurement of infant-parent attachment, have examined antenatal depression as a predictor of attachment, and none has also included a measure of maternal trauma. This study uses data on 224 women recruited in early pregnancy and followed up until 12 months postpartum. Maternal depression was measured in pregnancy using the Structured Clinical Interview for the DSM and repeat Edinburgh Postnatal Depression Scale as well as Stressful Life Events scale across pregnancy and postpartum including items on domestic violence. A past history of trauma was measured using the Childhood Trauma Questionnaire. Attachment was measured using the Strange Situation Procedure (SSP) at 12 months postpartum. We found that maternal depression was not associated with insecure or disorganized attachment. However, a maternal history of childhood trauma and current domestic violence both predicted insecure-avoidant attachment at 12 months, whereas increased number of stressful life events prior to conception and in pregnancy was associated with insecure-resistant attachment. Neither trauma, past or current, nor depression predicted disorganized attachment. In the first study to have included measures of antenatal depression, maternal childhood trauma, and current stressful events as predictors of infant attachment measured using the SSP, we found maternal experiences of past and current trauma but not depression were significant predictors of infant-parent attachment security.

Major depression as a predictor of the intergenerational transmission of attachment security: Findings from a pregnancy cohort study.

OBJECTIVE: Understanding the relationship between attachment and mental health has an important role in informing management of perinatal mental disorders and for infant mental health. It has been suggested that experiences of attachment are transmitted from one generation to the next. Maternal sensitivity has been proposed as a mediator, although findings have not been as strong as hypothesised. A meta-analysis suggested that this intergenerational transmission of attachment may vary across populations with lower concordance between parent and infant attachment classifications in clinical compared to community samples. However, no previous study has examined major depression and adult attachment in pregnancy as predictors of infant-parent attachment classification at 12 months postpartum. METHODS: Data were obtained on 52 first-time mothers recruited in early pregnancy, which included 22 women who met diagnostic criteria for current major depression using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders. The Adult Attachment Interview was also administered before 20 weeks of pregnancy. A history of early trauma was measured using the Childhood Trauma Questionnaire and maternal sensitivity was measured at 6 months postpartum using the observational measure of the Emotional Availability Scales. Infant-parent attachment was measured using the Strange Situation Procedure at 12 months. RESULTS: Overall, we found no significant association between the Adult Attachment Interview and the Strange Situation Procedure classifications. However, a combination of maternal non-autonomous attachment on the Adult Attachment Interview and major depression was a significant predictor of insecure attachment on the Strange Situation Procedure. We did not find that maternal sensitivity mediated parental and infant attachment security in this sample. CONCLUSION: While previous meta-analyses identified lower concordance in clinical samples, our findings suggest women with major depression and non-autonomous attachment have a greater concordance with insecure attachment on the Strange Situation Procedure. These findings can guide future research and suggest a focus on depression in pregnancy may be important for subsequent infant attachment.

Harry Harlow's pit of despair: Depression in monkeys and men.

Major depressive disorder is the most common mood disorder in the United States today and the need for adequate treatment has been universally desired for over a century. Harry Harlow, famous for his research with rhesus monkeys, was heavily criticized when he undertook his controversial experiments trying to find a solution for depression in the 1960s-1970s. His research, however, did not just evolve gradually from his earlier research into learning and into love. Recently disclosed hand-written notes show, for the first time, the severity of Harlow's depressions as he wrote in detail about his feelings and thoughts during his stay in a mental hospital in 1968. In these notes, Harlow repeatedly vowed to put every effort into finding a cure for depression. This may, for a large part, explain why he did not stop his rigorous animal experiments where critics argue he should have, and he eventually managed to book positive results.

Psychotic experiences and future school performance in childhood: a population-based cohort study.

BACKGROUND: Psychotic experiences are common in childhood and an important risk indicator of adverse mental health outcomes. However, little is known about the association of psychotic experiences with functional outcomes in childhood, particularly regarding school performance. The aim of the present study was to examine whether psychotic experiences were prospectively related to school performance in childhood. METHODS: This study was embedded in the population-based Generation R Study (N = 2,362). Psychotic experiences were assessed using self-reports on hallucinations at age 10 years. School performance was assessed using a standardized national school performance test at age 12 years. We considered the total school performance score, as well as language and mathematics subscales. Analyses were adjusted for sociodemographic characteristics, maternal nonverbal IQ, nonverbal IQ at age 6 years and co-occurring psychopathology at age 10 years. RESULTS: Psychotic experiences were prospectively associated with poorer school performance scores (B = -0.61, 95% CI [-0.98;-0.25], p = .001), as well as poorer language (Bpercentile rank score  = -2.00, 95% CI [-3.20;-0.79], p = .001) and mathematical ability (Bpercentile rank score  = -1.75, 95% CI [-2.99;-0.51], p = .006). These associations remained after additional adjustment for nonverbal IQ at age 6 years (B = -0.51, 95% CI [-0.86;-0.16], p = .005), and co-occurring internalizing (B = -0.40, 95% CI [-0.77;-0.03], p = .036) and externalizing problems (B = -0.40, 95% CI [-0.75;-0.04], p = .029), but not attention problems (B = -0.10, 95% CI [-0.47;0.26], p = .57). CONCLUSIONS: Children with psychotic experiences had lower school performance scores than their nonaffected peers. The finding was independent of sociodemographic characteristics, intelligence and co-occurring internalizing and externalizing problems, but not attention problems. This study suggests that psychotic experiences are associated with childhood functional impairments, although the relatively small effects and the role of attention problems warrant further exploration.

Aggressive behavior, emotional, and attention problems across childhood and academic attainment at the end of primary school.

PURPOSE: To assess whether aggressive behavior and emotional problems from early childhood onwards are related to academic attainment at the end of primary education, and whether these associations are independent of attention problems. METHODS: Data on 2546 children participating in a longitudinal birth cohort in Rotterdam were analyzed. Aggressive behavior, attention and emotional problems at ages 1½, 3, 5 and 10 years were assessed with the Child Behavior Checklist. Academic attainment at the end of primary school (12 years of age) was measured with the CITO test, a national Dutch academic test score. RESULTS: Aggressive behavior from age 1½ to 10 years was negatively associated with academic attainment, but these associations attenuated to non-significance when accounting for comorbid attention problems. For emotional problems, first, only problems at 10 years were associated with poorer academic attainment. Yet, when accounting for attention problems, the association reversed: more emotional problems from 1½ to 10 years were associated with a better academic attainment. Attention problems at ages 1½ to 10 years were negatively associated with academic attainment, independent of comorbid emotional problems or aggressive behavior. CONCLUSIONS: Attention problems across childhood are related to a poorer academic attainment, while emotional problems predicted better academic attainment. Moreover, the relationship between aggressive behavior and academic attainment was explained by comorbid attention problems. Future research should determine the mechanisms through which attention problems and emotional problems affect academic attainment, to inform strategies for the promotion of better educational attainment.

The Complex Role of Parental Separation in the Association between Family Conflict and Child Problem Behavior.

Parental separation is a major adverse childhood experience. Parental separation is generally preceded by conflict, which is itself a risk factor for child problem behavior. Whether parental separation independent of conflict has negative effects on child problem behavior is unclear. This study was embedded in Generation R, a population-based cohort followed from fetal life until age 9 years. Information on family conflict was obtained from 5,808 mothers and fathers. The 4-way decomposition method was used to apportion the effects of prenatal family conflict and parental separation on child problem behavior into 4 nonoverlapping components. Structural equation modeling was used to test bidirectional effects of child problem behavior and family conflict over time. Family conflict from pregnancy onward and parental separation each strongly predicted child problem behavior up to preadolescence according to maternal and paternal ratings. Using the 4-way decomposition method, we found evidence for a strong direct effect of prenatal family conflict on child problem behavior, for reference interaction, and for mediated interaction. The evidence for interaction implies that prenatal family conflict increased the children's vulnerability to the harmful effect of parental separation. There was no evidence of a pure indirect effect of parental separation on child problem behavior. Overall, results indicated that if parental separation occurs in families with low levels of conflict, parental separation does not predict more child problem behavior. Moreover, the bidirectional pattern suggested that child problem behavior influences the persistence of family conflict.

Preschool family irregularity and the development of sleep problems in childhood: a longitudinal study.

BACKGROUND: Previous studies have shown that poor family environments are related to more sleep problems; however, little is known about how family irregularity in early life affects the development of sleep problems over childhood using objective sleep measures. The current study tests the hypothesis that early family irregularity contributes to the development of sleep problems. METHODS: This population-based study comprises 5,443 children from the Generation R Study. Family irregularity was measured with seven maternal-reported questions on family routines when children were 2 and 4 years old. Mothers reported on sleep problems at child age 3, 6, and 10 years, whereas children completed questionnaires on sleep problems at age 10. Additionally, we used tri-axial wrist accelerometers for five nights in 851 children (mean age 11.7 years) to assess sleep objectively. RESULTS: Family irregularity was associated with more mother- and child-reported sleep problems at ages 3, 6, and 10 years as well as with a shorter sleep duration and later objective sleep onset, but not with sleep efficiency or waking time. The association between family irregularity and multi-informant subjective sleep problems at age 10 years was mediated by mother-reported child psychopathology at age 6 years. CONCLUSIONS: Our findings show a long-term robust association of preschool family irregularity with more sleep problems during childhood as well as shorter sleep duration and later sleep onset as measured objectively with actigraphy. In part, these sleep problems were associated with family irregularity by way of child psychopathology. These findings suggest that interventions improving preschool family irregularity, which are targeted to reduce child psychopathology, may also impact the development of sleep problems beneficially.

Prenatal and early postnatal measures of brain development and childhood sleep patterns.

BackgroundBrain development underlies maturation of sleep patterns throughout childhood. Intrauterine head growth-marker of early neurodevelopment-has not been associated with childhood sleep characteristics. We explored associations between ultrasonographic measures of prenatal and early postnatal neurodevelopment and childhood sleep.MethodsA total of 6,808 children from a population-based birth cohort (Generation R) were included. Head circumference (HC) and lateral ventricles size were assessed with mid- and late-pregnancy fetal ultrasounds, and with cranial ultrasound 3-20 weeks postnatally. Mothers reported children's sleep duration at 2 and 3 years, and sleep problems at 1.5, 3, and 6 years.ResultsLarger ventricular size, but not HC, was related to longer sleep duration at 3 years (ß=0.06 h, 95% confidence interval (CI): 0.02; 0.10 in late-pregnancy and ß=0.11 h, 95% CI: 0.02; 0.20 in early infancy, mid-pregnancy parameters were unrelated to sleep duration). Larger HC in mid-pregnancy was associated with a reduced risk for being a "problematic sleeper" up to the age of 6 years (odds ratio (OR): 0.94, 95% CI: 0.89; 0.99). Consistently, children with larger HC in early infancy were less likely to be "problematic sleepers" at 3 and 6 years.ConclusionsThis study shows that variations in fetal and neonatal brain size may underlie behavioral expression of sleep in childhood. Albeit small effect estimates, these associations provide evidence for neurodevelopmental origins of sleep.

The Prospective Association of the Diurnal Cortisol Rhythm With Sleep Duration and Perceived Sleeping Problems in Preschoolers: The Generation R Study.

OBJECTIVE: Cortisol, the end product of the hypothalamic-pituitary-adrenal axis, plays an important role in modulating sleep. Yet, studies investigating the association between diurnal cortisol rhythm and sleep patterns in young children are scarce. We tested the hypothesis that the diurnal cortisol rhythm is associated with shorter sleep duration and more sleep problems across early childhood. METHODS: This study was embedded in Generation R, a population-based cohort from fetal life onward. Parents collected saliva samples from their infant at five moments during day 1. In 322 infants aged 12 to 20 months, we determined the diurnal cortisol rhythm by calculating the area under the curve (AUC), the cortisol awakening response (CAR), and the diurnal slope. Sleep duration and sleep behavior were repeatedly assessed across ages of 14 months to 5 years. Generalized estimating equation models were used to assess related cortisol measures to sleep duration and sleep behavior. RESULTS: The diurnal cortisol slope and the CAR, but not the AUC, were associated with sleep duration across childhood. Children with flatter slopes and children with a more positive CAR were more likely to have shorter nighttime sleep duration (ß per nmol/L/h slope = -0.12, 95% confidence interval = -0.19 to -0.05, p = .001; ß per nmol/L CAR = -0.01, 95% confidence interval = -0.02 to 0.00, p = .04). Cortisol measures did not predict sleep problems. CONCLUSIONS: The present study suggests that a flatter diurnal cortisol slope and a more marked morning rise, which can indicate stress (or hypothalamic-pituitary-adrenal dysregulation), have a long-term association with sleep regulation.

Methylation matters: FK506 binding protein 51 (FKBP5) methylation moderates the associations of FKBP5 genotype and resistant attachment with stress regulation.

The parent-child attachment relationship plays an important role in the development of the infant's stress regulation system. However, genetic and epigenetic factors such as FK506 binding protein 51 (FKBP5) genotype and DNA methylation have also been associated with hypothalamus-pituitary-adrenal axis functioning. In the current study, we examined how parent-child dyadic regulation works in concert with genetic and epigenetic aspects of stress regulation. We study the associations of attachment, extreme maternal insensitivity, FKBP5 single nucleotide polymorphism 1360780, and FKBP5 methylation, with cortisol reactivity to the Strange Situation Procedure in 298 14-month-old infants. The results indicate that FKBP5 methylation moderates the associations of FKBP5 genotype and resistant attachment with cortisol reactivity. We conclude that the inclusion of epigenetics in the field of developmental psychopathology may lead to a more precise picture of the interplay between genetic makeup and parenting in shaping stress reactivity.

ASSOCIATION BETWEEN INFANT NIGHTTIME-SLEEP LOCATION AND ATTACHMENT SECURITY: NO EASY VERDICT.

We tested whether mother-infant bed-sharing is associated with increased secure infant-mother attachment, a previously unexplored association. Frequency of bed-sharing and mothers' nighttime comforting measures at 2 months were assessed with questionnaires in 550 Caucasian mothers from a population-based cohort. Attachment security was assessed with the Strange Situation Procedure (M.D.S. Ainsworth, M.C. Blehar, E. Waters, & S. Wall, 1978) at 14 months. When using a dichotomous variable, "never bed-sharing" (solitary sleepers) versus "any bed-sharing," the relative risk of being classified as insecurely attached for solitary-sleeping infants (vs. bed-sharers) was 1.21 (95% confidence interval: 1.05-1.40). In multivariate models, solitary sleeping was associated with greater odds of insecure attachment, adjusted odds ratio (OR): 1.50, 95% CI = 1.02-2.20) and, in particular, with greater odds of resistant attachment, adjusted OR = 1.74, 95% CI = 1.10-2.76); and with a lower attachment security score, ß = -0.12, t(495) = -2.61, p = .009. However, we found no evidence of a dose-response association between bed-sharing and secure attachment when using a trichotomous bed-sharing variable based on frequency of bed-sharing. Our findings demonstrate some evidence that solitary sleeping is associated with insecure attachment. However, the lack of a dose-response association suggests that further experimental study is necessary before accepting common notions that sharing a bed leads to children who are better or not better adjusted.

Is parent-child bed-sharing a risk for wheezing and asthma in early childhood?

Household crowding can place young children at risk for respiratory infections which subsequently provoke asthma symptoms. However, crowding might also protect against asthma, in accordance with the hygiene hypothesis. We tested if parent-infant bed-sharing, an important dimension of household crowding, increases or decreases the risk for asthma. In a population-based prospective cohort (N = 6160) we assessed bed-sharing at 2 and 24 months; wheezing between 1 and 6 years of age; and asthma at 6 years of age. Generalised estimating equation models were used to assess repeated measures of wheezing and asthma. We found no association between bed-sharing in early infancy and wheezing or diagnosis of asthma. By contrast, we found a positive association between bed-sharing in toddlerhood and both wheezing (OR 1.42, 95% CI 1.15-1.74) and asthma (OR 1.57, 95% CI 1.03-2.38). Wheezing was not associated with bed-sharing when using cross-lagged modelling. This study suggests that bed-sharing in toddlerhood is associated with an increased risk of asthma at later ages, and not vice versa. Further studies are needed to explore the underlying causal mechanisms.

Beyond the usual suspects: a multidimensional genetic exploration of infant attachment disorganization and security.

Although the environmental influences on infant attachment disorganization and security are well-studied, little is known about their heritability. Candidate gene studies have shown small, often non-replicable effects. In this study, we gathered the largest sample (N = 657) of ethnically homogenous, 14-month-old children with both observed attachment and genome-wide data. First, we used a Genome-Wide Association Study (GWAS) approach to identify single nucleotide polymorphisms (SNPs) associated with attachment disorganization and security. Second, we annotated them into genes (Versatile Gene-based Association Study) and functional pathways. Our analyses provide evidence of novel genes (HDAC1, ZNF675, BSCD1) and pathways (synaptic transmission, cation transport) associated with attachment disorganization. Similar analyses identified a novel gene (BECN1) but no distinct pathways associated with attachment security. The results of this first extensive, exploratory study on the molecular-genetic basis of infant attachment await replication in large, independent samples.

Attachment security and disorganization in infants of mothers with severe psychiatric disorder: Exploring the role of comorbid personality disorder.

The aim of this preliminary study was to explore infant-mother attachment quality in a Dutch clinical sample of mothers with severe psychiatric disorder, with or without comorbid personality disorder. Thirty-two mothers were recruited through specialized secondary and tertiary outpatient clinics and mental health institutions. Maternal psychiatric and personality diagnoses were verified with structured clinical interviews during pregnancy. Maternal concurrent level of psychiatric symptoms was assessed by self-report and infant-mother attachment quality by observation in the Strange Situation Procedure at 14 months postpartum. In the full sample, almost half of the infants were classified as disorganized. All infants of mothers with a comorbid personality disorder were classified as either insecure or disorganized. Infants of mothers with a comorbid personality disorder had a significantly higher disorganization score than infants of mothers with a psychiatric disorder only. Continuous attachment security scores did not differ significantly between groups. In the full sample, continuous infant attachment security and disorganization score were not significantly correlated with the level of maternal concurrent psychiatric symptoms. Our exploratory findings suggest a specific link between maternal psychiatric and comorbid personality disorder and attachment disorganization. Moreover, chronicity of symptoms appears more relevant for attachment behaviors than the severity of concurrent psychiatric symptoms. Maternal personality disorder may have a strong formative impact on infant attachment security and disorganization, which warrants further research to inform clinical practice, in order to reduce the risk of intergenerational transmission of maternal psychopathology.

Maternal lifetime history of depression and depressive symptoms in the prenatal and early postnatal period do not predict infant-mother attachment quality in a large, population-based Dutch cohort study.

We examined the effects of maternal history of depressive disorder and the effects of depressive symptoms during pregnancy and the early postpartum period on attachment insecurity and disorganization. A total of 627 mother-infant dyads from the Generation R Study participated in a population-based cohort from fetal life onwards. Maternal history of depression was assessed by diagnostic interviews during pregnancy; maternal peri- and postnatal depressive symptoms were assessed with questionnaires in 506 of these women at 20 weeks pregnancy and two months postpartum; and infant-mother attachment security was observed when infants were aged 14 months. A history of maternal depressive disorder, regardless of severity or psychiatric comorbidity, was not associated with an increased risk of infant attachment insecurity or disorganization. Likewise, maternal peri- and postnatal depressive symptoms were not related to attachment insecurity or disorganization at 14 months. These results are important because mothers from otherwise low risk backgrounds often have previously been depressed or are struggling with non-clinical depressive symptoms during pregnancy and after giving birth. Our findings are discussed in terms of protective factors that may limit the potentially negative effects of maternal depressive symptoms on the infant-mother attachment relationship in the general population. The role of selective attrition and lack of information about the mothers' attachment status for the current null-findings are also discussed.

Dopaminergic, serotonergic, and oxytonergic candidate genes associated with infant attachment security and disorganization? In search of main and interaction effects.

BACKGROUND AND METHODS: In two birth cohort studies with genetic, sensitive parenting, and attachment data of more than 1,000 infants in total, we tested main and interaction effects of candidate genes involved in the dopamine, serotonin, and oxytocin systems (DRD4, DRD2, COMT, 5-HTT, OXTR) on attachment security and disorganization. Parenting was assessed using observational rating scales for parental sensitivity (Ainsworth, Bell, & Stayton, 1974), and infant attachment was assessed with the Strange Situation Procedure. RESULTS: We found no consistent additive genetic associations for attachment security and attachment disorganization. However, specific tests revealed evidence for a codominant risk model for COMT Val158Met, consistent across both samples. Children with the Val/Met genotype showed higher disorganization scores (combined effect size d = .22, CI = .10-.34, p < .001). Gene-by-environment interaction effects were not replicable across the two samples. CONCLUSIONS: This unexpected finding might be explained by a broader range of plasticity in heterozygotes, which may increase susceptibility to environmental influences or to dysregulation of emotional arousal. This study is unique in combining the two largest attachment cohorts with molecular genetic and observed rearing environment data to date.

Children's autistic traits and peer relationships: do non-verbal IQ and externalizing problems play a role?

BACKGROUND: Children with autism have difficulties in understanding relationships, yet little is known about the levels of autistic traits with regard to peer relationships. This study examined the association between autistic traits and peer relationships. Additionally, we examined whether the expected negative association is more pronounced in children with a lower non-verbal IQ and in those who exhibit more externalizing problems. METHOD: Data were collected in a large prospective birth cohort of the Generation R Study (Rotterdam, the Netherlands) for which nearly 10,000 pregnant mothers were recruited between 2002 and 2006. Follow up data collection is still currently ongoing. Information on peer relationships was collected with PEERS application, an interactive computerized task (M = 7.8 years). Autistic traits were assessed among general primary school children by using the Social Responsiveness Scale (M = 6.1 years). Information was available for 1580 children. RESULT: Higher levels of autistic traits predicted lower peer acceptance and higher peer rejection. The interaction of autistic traits with externalizing problems (but not with non-verbal IQ or sex) was significant: only among children with low externalizing problems, a higher level of autistic traits predicted less peer acceptance and more peer rejection. Among children exhibiting high externalizing problems, a poor peer acceptance and high level of rejection is seen independently of the level of autistic traits. CONCLUSION: We conclude that autistic traits-including traits that do not classify as severe enough for a clinical diagnosis-as well as externalizing problems negatively impact young children's peer relationships. This suggests that children with these traits may benefit from careful monitoring and interventions focused at improving peer relationships.