Psychotic experiences, suicidality and non-suicidal self-injury in adolescents: Independent findings from two cohorts.

BACKGROUND: Prior studies have shown that psychotic experiences are prospectively associated with an increased risk of suicidality. However, it is unclear whether this association is causal or arises from shared risk factors. Furthermore, little is known about the association between psychotic experiences and non-suicidal self-injury (NSSI). METHODS: We used data from two independent samples of young adolescents, which we analyzed separately. In a population-based cohort, data on hallucinatory experiences and suicidality were collected at ages 10 and 14 years (N = 3435). In a cross-sectional study of a population oversampled for elevated psychopathology levels, psychotic experiences, suicidality, and NSSI were assessed at age 15 years (N = 910). Analyses were adjusted for sociodemographic covariates, maternal psychopathology, intelligence, childhood adversity, and mental health problems. RESULTS: Psychotic experiences were prospectively associated with an increased risk of suicidality, even when considering self-harm ideation at baseline. Furthermore, persistent and incident, but not remittent, patterns of psychotic experiences were related to an increased burden of suicidality. Self-harm ideation was also prospectively associated with the risk for psychotic experiences, although of smaller magnitude and only by self-report. Among at-risk adolescents, psychotic experiences were cross-sectionally associated with a greater burden of suicidality and a higher frequency of NSSI events, with more extensive tissue damage. CONCLUSION: Psychotic experiences are longitudinally associated with suicidality beyond the effects of shared risk factors. We also found modest support for reverse temporality, which warrants further investigation. Overall, our findings highlight the importance of assessing psychotic experiences as an index of risk for suicidality and NSSI.

Hallucinations and Brain Morphology Across Early Adolescence: A Longitudinal Neuroimaging Study.

BACKGROUND: Psychotic disorders have been widely associated with structural brain abnormalities. However, it is unclear whether brain structure predicts psychotic experiences in youth from the general population, owing to an overall paucity of studies and predominantly cross-sectional designs. Here, the authors investigated longitudinal associations between brain morphology and hallucinations from childhood to early adolescence. METHODS: This study was embedded in the population-based Generation R Study. Children underwent structural neuroimaging at age 10 years (N = 2042); a subsample received a second scan at age 14 years (n = 964). Hallucinations were assessed at ages 10 and 14 years and studied as a binary variable. Cross-lagged panel models and generalized linear mixed-effects models were fitted to examine longitudinal associations between brain morphology and hallucinations. RESULTS: Smaller total gray and white matter volumes and total cortical surface area at baseline were associated with a higher occurrence of hallucinations between ages 10 and 14 years. The regions associated with hallucinations were widespread, including the frontal, parietal, temporal, and occipital lobes, as well as the insula and cingulate cortex. Analyses of subcortical structures revealed that smaller baseline hippocampal volumes were longitudinally associated with hallucinations, although this association was no longer significant following adjustment for intracranial volume. No evidence for reverse temporality was observed (i.e., hallucinations predicting brain differences). CONCLUSIONS: The findings from this longitudinal study suggest that global structural brain differences are associated with the development of hallucinations. These results extend findings from clinical populations and provide evidence for a neurodevelopmental vulnerability across the psychosis continuum.

Maternal age, autistic-like traits and mentalizing as predictors of child autistic-like traits in a population-based cohort.

BACKGROUND: Many empirical studies suggest that higher maternal age increases the likelihood of having an autistic child. However, little is known about factors that may explain this relationship or if higher maternal age is related to the number of autistic-like traits in offspring. One possibility is that mothers who have a higher number of autistic-like traits, including greater challenges performing mentalizing skills, are delayed in finding a partner. The goal of our study is to assess the relationship between maternal age, mentalizing skills and autistic-like traits as independent predictors of the number of autistic-like traits in offspring. METHODS: In a population-based study in the Netherlands, information on maternal age was collected during pre- and perinatal enrolment. Maternal mentalizing skills and autistic-like traits were assessed using the Reading the Mind in the Eyes Test and the Autism Spectrum Quotient, respectively. Autistic-like traits in children were assessed with the Social Responsiveness Scale. A total of 5718 mother/child dyads had complete data (Magechild = 13.5 years; 50.2% girls). RESULTS: The relationship between maternal age and autistic-like traits in offspring best fits a U-shaped curve. Furthermore, higher levels of autistic features in mothers are linked to higher levels of autistic-like traits in their children. Lower mentalizing performance in mothers is linked to higher levels of autistic-like traits in their children. LIMITATIONS: We were able to collect data on both autistic-like traits and the mentalizing skills test in a large population of mothers, but we did not collect these data in a large number of the fathers. CONCLUSIONS: The relationships between older and younger mothers may have comparable underlying mechanisms, but it is also possible that the tails of the U-shaped curve are influenced by disparate mechanisms.

Schizophrenia polygenic risk is associated with child mental health problems through early childhood adversity: evidence for a gene-environment correlation.

Previous studies have shown that schizophrenia polygenic risk predicts a multitude of mental health problems in the general population. Yet it is unclear by which mechanisms these associations arise. Here, we explored a possible gene-environment correlation in the association of schizophrenia polygenic risk with mental health problems via childhood adversity. This study was embedded in the population-based Generation R Study, including N = 1901 participants with genotyping for schizophrenia polygenic risk, maternal reporting of childhood adversity, and Child Behaviour Checklist measurement of mental health problems. Independent replication was attempted in the Avon Longitudinal Study of Parents and Children (ALSPAC; N = 3641). Associations were analysed with Poisson regression and statistical mediation analysis. Higher burden of schizophrenia polygenic risk was associated with greater exposure to childhood adversity (P-value threshold < 0.5: Generation R Study, OR = 1.08, 95%CI 1.02-1.15, P = 0.01; ALSPAC, OR = 1.02, 95%CI 1.01-1.03, P < 0.01). Childhood adversities partly explained the relationship of schizophrenia polygenic risk with emotional, attention, and thought problems (proportion explained, range 5-23%). Direct effects of schizophrenia polygenic risk and adversity on mental health outcomes were also observed. In summary, genetic liability to schizophrenia increased the risk for mental health problems in the general paediatric population through childhood adversity. Although this finding could result from a mediated causal relationship between genotype and mental health, we argue that these observations most likely reflect a gene-environment correlation, i.e. adversities are a marker for the genetic risk that parents transmit to children. These and similar recent findings raise important conceptual questions about preventative interventions aimed at reducing childhood adversities.

Peer-reported bullying, rejection and hallucinatory experiences in childhood.

OBJECTIVE: Psychotic experiences, such as hallucinations, occur commonly in children and have been related to bullying victimization. However, whether bullying perpetration, peer rejection, or peer acceptance are related to hallucinatory experiences has remained under-examined. We used a novel peer nomination method to examine whether (i) bullying perpetration and (ii) social positions within peer networks were associated with future hallucinatory experiences. METHODS: This prospective study was embedded in the population-based Generation R Study. Bullying perpetration, peer rejection, and peer acceptance were assessed using peer nominations at age 7 years (N = 925). Using a social network analysis, we estimated social positions within peer rejection and acceptance networks. Bullying victimization was assessed using self-reports. Self-reported hallucinatory experiences were assessed at age 10 years. Analyses were adjusted for sociodemographic covariates. RESULTS: Higher levels of bullying perpetration were prospectively associated with an increased burden of hallucinatory experiences (OR = 1.22, 95% CI 1.05-1.43, p = 0.011). Bullies had a 50% higher, and bully-victims had a 89% higher odds, of endorsing hallucinatory experiences three years later than children who were not involved in bullying (ORbully = 1.50, 95% CI 1.01-2.24, p = 0.045; ORbully-victim = 1.89, 95% CI 1.15-3.10, p = 0.012). Unfavorable positions within peer rejection networks, but not peer acceptance networks, were associated with an increased risk for hallucinatory experiences (ORpeer rejection = 1.24, 95% CI 1.07-1.44, pFDR-corrected = 0.024). CONCLUSION: Using peer reports, we observed that bullies and socially rejected children have a higher likelihood to report hallucinatory experiences in pre-adolescence. Children who are both a bully and a victim of bullying (ie, bully-victims) may be particularly vulnerable for psychotic experiences.

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.

Predicting persistence of hallucinations from childhood to adolescence.

BACKGROUND: Psychotic experiences predict adverse health outcomes, particularly if they are persistent. However, it is unclear what distinguishes persistent from transient psychotic experiences. AIMS: In a large population-based cohort, we aimed to (a) describe the course of hallucinatory experiences from childhood to adolescence, (b) compare characteristics of youth with persistent and remittent hallucinatory experiences, and (c) examine prediction models for persistence. METHOD: Youth were assessed longitudinally for hallucinatory experiences at mean ages of 10 and 14 years (n = 3473). Multi-informant-rated mental health problems, stressful life events, self-esteem, non-verbal IQ and parental psychopathology were examined in relation to absent, persistent, remittent and incident hallucinatory experiences. We evaluated two prediction models for persistence with logistic regression and assessed discrimination using the area under the curve (AUC). RESULTS: The persistence rate of hallucinatory experiences was 20.5%. Adolescents with persistent hallucinatory experiences had higher baseline levels of hallucinatory experiences, emotional and behavioural problems, as well as lower self-esteem and non-verbal IQ scores than youth with remittent hallucinatory experiences. Although the prediction model for persistence versus absence of hallucinatory experiences demonstrated excellent discriminatory power (AUC-corrected = 0.80), the prediction model for persistence versus remittance demonstrated poor accuracy (AUC-corrected = 0.61). CONCLUSIONS: This study provides support for the dynamic expression of childhood hallucinatory experiences and suggests increased neurodevelopmental vulnerability in youth with persistent hallucinatory experiences. Despite the inclusion of a wide array of psychosocial parameters, a prediction model discriminated poorly between youth with persistent versus remittent hallucinatory experiences, confirming that persistent hallucinatory experiences are a complex multifactorial trait.

Environment-Wide Association Study (En WAS) of Prenatal and Perinatal Factors Associated With Autistic Traits: A Population-Based Study.

A combination of genetic and environmental factors contributes to the origins of autism spectrum disorder (ASD). While a number of studies have described specific environmental factors associating with emerging ASD, studies that compare and contrast multiple environmental factors in the same study are lacking. Thus, the goal of this study was to perform a prospective, data-driven environmental-wide association study of pre- and perinatal factors associated with the later development of autistic symptoms in childhood. The participants included 3891 6-year-old children from a birth cohort with pre- and perinatal data. Autistic symptoms were measured using the Social Responsiveness Scale in all children. Prior to any analyses, the sample was randomly split into a discovery set (2920) and a test set (921). Multiple linear regression analyses were performed for each of 920 variables, correcting for six of the most common covariates in epidemiological studies. We found 111 different pre- and perinatal factors associated with autistic traits during childhood. In secondary analyses where we controlled for parental psychopathology, 23 variables in the domains of family and interpersonal relationships were associated with the development of autistic symptoms during childhood. In conclusion, a data-driven approach was used to identify a number of pre- and perinatal risk factors associating with higher childhood autistic symptoms. These factors include measures of parental psychopathology and family and interpersonal relationships. These measures could potentially be used for the early identification of those at increased risk to develop ASD. LAY SUMMARY: A combination of genetic and environmental factors contributes to the development of autism spectrum disorder (ASD). Each environmental factor may affect the risk of ASD. In a study on 6-year-old children, a number of pre- and perinatal risk factors were identified that are associated with autistic symptoms in childhood. These factors include measures of parental psychopathology and family and interpersonal relationships. These variables could potentially serve as markers to identify those at increased risk to develop ASD or autistic symptoms. Autism Res 2020, 13: 1582-1600. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.

Autistic traits and neuropsychological performance in 6- to-10-year-old children: a population-based study.

Clinical studies of children with autism spectrum disorder (ASD) provide evidence for poorer neuropsychological performance within specific domains compared to age, gender, and sometimes IQ-matched controls. Since recent evidence suggests that autistic symptoms form a spectrum that extends into the general population, it was our goal to evaluate the nature of the relationship between autistic traits and neuropsychological performance across the continuum in the general population. We examined neuropsychological performance across five different domains in 1019 6-to-10-year-old children participating in a population-based study of child development. Autistic traits were assessed when the children were 6 years of age using the Social Responsiveness Scale and ASD diagnoses were obtained via medical records. Neuropsychological functioning was measured using the NEPSY-II-NL and included the domains of attention and executive function, memory and learning, sensorimotor functioning, language, and visuospatial functioning. We found that children with higher autistic traits showed significantly lower neuropsychological performance in all domains investigated and that this association remained even after excluding children with the highest autistic traits or confirmed ASD. When comparing 41 children with confirmed ASD diagnosis to typically developing controls, children with ASD showed significantly lower neuropsychological performance across all domains. Taken together, our results suggest that children with both ASD and subclinical autistic traits have lower neuropsychological performance. Thus, this may provide an understanding of why some children without an ASD diagnosis may require some additional assistance within academic settings.

Connectivity dynamics in typical development and its relationship to autistic traits and autism spectrum disorder.

Recent advances in neuroimaging techniques have provided significant insights into developmental trajectories of human brain function. Characterizations of typical neurodevelopment provide a framework for understanding altered neurodevelopment, including differences in brain function related to developmental disorders and psychopathology. Historically, most functional connectivity studies of typical and atypical development operate under the assumption that connectivity remains static over time. We hypothesized that relaxing stationarity assumptions would reveal novel features of both typical brain development related to children on the autism spectrum. We employed a "chronnectomic" (recurring, time-varying patterns of connectivity) approach to evaluate transient states of connectivity using resting-state functional MRI in a population-based sample of 774 6- to 10-year-old children. Dynamic connectivity was evaluated using a sliding-window approach, and revealed four transient states. Internetwork connectivity increased with age in modularized dynamic states, illustrating an important pattern of connectivity in the developing brain. Furthermore, we demonstrated that higher levels of autistic traits and ASD diagnosis were associated with longer dwell times in a globally disconnected state. These results provide a roadmap to the chronnectomic organization of the developing brain and suggest that characteristics of functional brain connectivity are related to children on the autism spectrum.

The bidirectional association between sleep problems and autism spectrum disorder: a population-based cohort study.

Background: Sleep difficulties are prevalent in children with autism spectrum disorder (ASD). The temporal nature of the association between sleep problems and ASD is unclear because longitudinal studies are lacking. Our aim is to clarify whether sleep problems precede and worsen autistic traits and ASD or occur as a consequence of the disorder. Methods: Repeated sleep measures were available at 1.5, 3, 6, and 9 years of age in 5151 children participating in the Generation R Study, a large prospective birth cohort in the Netherlands. Autistic traits were determined with the Pervasive Developmental Problems score (PDP) of the Child Behavior Checklist (CBCL) at 1.5 and 3 years and the Social Responsiveness Scale (SRS) at 6 years. This cohort included 81 children diagnosed with ASD. Results: Sleep problems in early childhood were prospectively associated with a higher SRS score, but not when correcting for baseline PDP score. By contrast, a higher SRS score and an ASD diagnosis were associated with more sleep problems at later ages, even when adjusting for baseline sleep problems. Likewise, a trajectory of increasing sleep problems was associated with ASD. Conclusions: Sleep problems and ASD are not bidirectionally associated. Sleep problems do not precede and worsen autistic behavior but rather co-occur with autistic traits in early childhood. Over time, children with ASD have an increase in sleep problems, whereas typically developing children have a decrease in sleep problems. Our findings suggest that sleep problems are part of the construct ASD.

A prospective study of fetal head growth, autistic traits and autism spectrum disorder.

Altered trajectories of brain growth are often reported in Autism Spectrum Disorder (ASD), particularly during the first year of life. However, less is known about prenatal head growth trajectories, and no study has examined the relation with postnatal autistic symptom severity. The current study prospectively examined the association between fetal head growth and the spectrum of autistic symptom severity in two large population-based cohorts, including a sample of individuals with clinically diagnosed ASD. This study included 3,820 children from two longitudinal prenatal cohorts in The Netherlands and Australia, comprising 60 individuals with a confirmed diagnosis of ASD. Latent growth curve models were used to examine the relationship between fetal head circumference measured at three different time points and autistic traits measured in postnatal life using either the Social Responsiveness Scale or the Autism-Spectrum Quotient. While lower initial prenatal HC was weakly associated with increasing autistic traits in the Dutch cohort, this relationship was not observed in the Australian cohort, nor when the two cohorts were analysed together. No differences in prenatal head growth were found between individuals with ASD and controls. This large population-based study identified no consistent association across two cohorts between prenatal head growth and postnatal autistic traits. Our mixed findings suggest that further research in this area is needed. Autism Res 2018, 11: 602-612. © 2018 The Authors Autism Research published by International Society for Autism Research and Wiley Periodicals, Inc. LAY SUMMARY: It is not known whether different patterns of postnatal brain growth in Autism Spectrum Disorder (ASD) also occurs prenatally. We examined fetal head growth and autistic symptoms in two large groups from The Netherlands and Australia. Lower initial prenatal head circumference was associated with autistic traits in the Dutch, but not the Australian, group. No differences in head growth were found in individuals with ASD and controls when the data was combined. Our mixed findings suggest that more research in this area is needed.

Tracking Brain Development and Dimensional Psychiatric Symptoms in Children: A Longitudinal Population-Based Neuroimaging Study.

OBJECTIVE: Psychiatric symptomatology during childhood predicts persistent mental illness later in life. While neuroimaging methodologies are routinely applied cross-sectionally to the study of child and adolescent psychopathology, the nature of the relationship between childhood symptoms and the underlying neurodevelopmental processes remains unclear. The authors used a prospective population-based cohort to delineate the longitudinal relationship between childhood psychiatric problems and brain development. METHOD: A total of 845 children participated in the study. Psychiatric symptoms were measured with the parent-rated Child Behavior Checklist at ages 6 and 10. MRI data were collected at ages 8 and 10. Cross-lagged panel models and linear mixed-effects models were used to determine the associations between psychiatric symptom ratings and quantitative anatomic and white matter microstructural measures over time. RESULTS: Higher ratings for externalizing and internalizing symptoms at baseline predicted smaller increases in both subcortical gray matter volume and global fractional anisotropy over time. The reverse relationship did not hold; thus, baseline measures of gray matter and white matter were not significantly related to changes in symptom ratings over time. CONCLUSIONS: Children presenting with behavioral problems at an early age show differential subcortical and white matter development. Most neuroimaging models tend to explain brain differences observed in psychopathology as an underlying (causal) neurobiological substrate. However, the present work suggests that future neuroimaging studies showing effects that are pathogenic in nature should additionally explore the possibility of the downstream effects of psychopathology on the brain.

Paediatric population neuroimaging and the Generation R Study: the second wave.

Paediatric population neuroimaging is an emerging field that falls at the intersection between developmental neuroscience and epidemiology. A key feature of population neuroimaging studies involves large-scale recruitment that is representative of the general population. One successful approach for population neuroimaging is to embed neuroimaging studies within large epidemiological cohorts. The Generation R Study is a large, prospective population-based birth-cohort in which nearly 10,000 pregnant mothers were recruited between 2002 and 2006 with repeated measurements in the children and their parents over time. Magnetic resonance imaging was included in 2009 with the scanning of 1070 6-to-9-year-old children. The second neuroimaging wave was initiated in April 2013 with a total of 4245 visiting the MRI suite and 4087 9-to-11-year-old children being scanned. The sequences included high-resolution structural MRI, 35-direction diffusion weighted imaging, and a 6 min and 2 s resting-state functional MRI scan. The goal of this paper is to provide an overview of the imaging protocol and the overlap between the neuroimaging data and metadata. We conclude by providing a brief overview of results from our first wave of neuroimaging, which highlights a diverse array of questions that can be addressed by merging the fields of developmental neuroscience and epidemiology.

Gestational vitamin D deficiency and autism spectrum disorder.

BACKGROUND: There is growing interest in linking vitamin D deficiency with autism spectrum disorders (ASDs). The association between vitamin D deficiency during gestation, a critical period in neurodevelopment, and ASD is not well understood. AIMS: To determine the association between gestational vitamin D status and ASD. METHOD: Based on a birth cohort (n=4334), we examined the association between 25-hydroxyvitamin D (25OHD), assessed from both maternal mid-gestation sera and neonatal sera, and ASD (defined by clinical records; n=68 cases). RESULTS: Individuals in the 25OHD-deficient group at mid-gestation had more than twofold increased risk of ASD (odds ratio (OR)=2.42, 95% confidence interval (CI) 1.09 to 5.07, P=0.03) compared with the sufficient group. The findings persisted in analyses including children of European ethnicity only. CONCLUSIONS: Mid-gestational vitamin D deficiency was associated with an increased risk of ASD. Because gestational vitamin D deficiency is readily preventable with safe, inexpensive and readily available supplementation, this risk factor warrants closer scrutiny. DECLARATION OF INTEREST: None. COPYRIGHT AND USAGE: © The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

White matter microstructure in children with autistic traits.

Autism spectrum disorder (ASD) is thought to arise from aberrant development of connections in the brain. Previous studies have identified differences in white matter microstructure in children with ASD, offering support to such hypotheses. While ASD is thought to represent the severe end of a spectrum of traits, there are no studies evaluating white matter microstructure in relation to autistic traits in children from the general population. In a population-based sample of 604 6-to-10 year-old children, we assessed the relation between a continuous measure of autistic traits and white matter microstructure, using both probabilistic tractography and Tract-Based Spatial Statistics (TBSS). Using the TBSS approach, a cluster in the left superior longitudinal fasciculus (SLF) was identified where autistic traits negatively associated with fractional anisotropy (FA). In addition, two clusters of lower axial diffusion were identified; one in the corpus callosum and another in the corticospinal tract. Part of the findings remained when excluding children with ASD and were paralleled with similar, trend-level differences in 19 children with ASD, compared to matched controls. This study showed localized associations between autistic traits on a continuum and white matter microstructure, which could indicate a continuum of the neurobiology along the spectrum of autistic symptoms.

Enhancing studies of the connectome in autism using the autism brain imaging data exchange II.

The second iteration of the Autism Brain Imaging Data Exchange (ABIDE II) aims to enhance the scope of brain connectomics research in Autism Spectrum Disorder (ASD). Consistent with the initial ABIDE effort (ABIDE I), that released 1112 datasets in 2012, this new multisite open-data resource is an aggregate of resting state functional magnetic resonance imaging (MRI) and corresponding structural MRI and phenotypic datasets. ABIDE II includes datasets from an additional 487 individuals with ASD and 557 controls previously collected across 16 international institutions. The combination of ABIDE I and ABIDE II provides investigators with 2156 unique cross-sectional datasets allowing selection of samples for discovery and/or replication. This sample size can also facilitate the identification of neurobiological subgroups, as well as preliminary examinations of sex differences in ASD. Additionally, ABIDE II includes a range of psychiatric variables to inform our understanding of the neural correlates of co-occurring psychopathology; 284 diffusion imaging datasets are also included. It is anticipated that these enhancements will contribute to unraveling key sources of ASD heterogeneity.

Infant muscle tone and childhood autistic traits: A longitudinal study in the general population.

In a longitudinal population-based study of 2,905 children, we investigated if infants' neuromotor development was associated with autistic traits in childhood. Overall motor development and muscle tone were examined by trained research assistants with an adapted version of Touwen's Neurodevelopmental Examination between ages 2 and 5 months. Tone was assessed in several positions and items were scored as normal, low, or high tone. Parents rated their children's autistic traits with the Social Responsiveness Scale (SRS) and the Pervasive Developmental Problems (PDP) subscale of the Child Behavior Checklist at 6 years. We defined clinical PDP if scores were >98th percentile of the norm population. Diagnosis of autism spectrum disorder (ASD) was clinically confirmed in 30 children. We observed a modest association between overall neuromotor development in infants and autistic traits. Low muscle tone in infancy predicted autistic traits measured by SRS (adjusted beta = 0.05, 95% CI for B: 0.00-0.02, P = 0.01), and PDP (adjusted beta = 0.08, 95% CI for B: 0.04-0.10, P < 0.001). Similar results emerged for the association of low muscle tone and clinical PDP (adjusted OR = 1.36, 95% CI: 1.08-1.72, P = 0.01) at age 6 years. Results remained unchanged if adjusted for child intelligence. There was no association between high muscle tone and SRS or PDP. Exclusion of children with ASD diagnosis did not change the association. This large study showed a prospective association of infant muscle tone with autistic traits in childhood. Our findings suggest that early detection of low muscle tone might be a gateway to improve early diagnosis of ASD. Autism Res 2017, 10: 757-768. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

The association of gender, age, and intelligence with neuropsychological functioning in young typically developing children: The Generation R study.

Although early childhood is a period of rapid neurocognitive development, few studies have assessed neuropsychological functioning in various cognitive domains in young typically developing children. Also, results regarding its association with gender and intelligence are mixed. In 853 typically developing children aged 6 to 10 years old, the association of gender, age, and intelligence with neuropsychological functioning in the domains of attention, executive functioning, language, memory, sensorimotor functioning, and visuospatial processing was explored. Clear positive associations with age were observed. In addition, gender differences were found and showed that girls generally outperformed boys, with the exception of visuospatial tasks. Furthermore, IQ was positively associated with neuropsychological functioning, which was strongest in visuospatial tasks. Performance in different neuropsychological domains was associated with age, gender, and intelligence in young typically developing children, and these factors should be taken into account when assessing neuropsychological functioning in clinical or research settings.