Childhood aggression and its resulting consequences inflict a huge burden on affected children, their relatives, teachers, peers and society as a whole. Aggression during childhood rarely occurs in isolation and is correlated with other symptoms of childhood psychopathology. In this paper, we aim to describe and improve the understanding of the co-occurrence of aggression with other forms of childhood psychopathology. We focus on the co-occurrence of aggression and other childhood behavioural and emotional problems, including other externalising problems, attention problems and anxiety–depression. The data were brought together within the EU-ACTION (Aggression in Children: unravelling gene-environment interplay to inform Treatment and InterventiON strategies) project. We analysed the co-occurrence of aggression and other childhood behavioural and emotional problems as a function of the child’s age (ages 3 through 16 years), gender, the person rating the behaviour (father, mother or self) and assessment instrument. The data came from six large population-based European cohort studies from the Netherlands (2x), the UK, Finland and Sweden (2x). Multiple assessment instruments, including the Child Behaviour Checklist (CBCL), the Strengths and Difficulties Questionnaire (SDQ) and Multidimensional Peer Nomination Inventory (MPNI), were used. There was a good representation of boys and girls in each age category, with data for 30,523 3- to 4-year-olds (49.5% boys), 20,958 5- to 6-year-olds (49.6% boys), 18,291 7- to 8-year-olds (49.0% boys), 27,218 9- to 10-year-olds (49.4% boys), 18,543 12- to 13-year-olds (48.9% boys) and 10,088 15- to 16-year-olds (46.6% boys). We replicated the well-established gender differences in average aggression scores at most ages for parental ratings. The gender differences decreased with age and were not present for self-reports. Aggression co-occurred with the majority of other behavioural and social problems, from both externalising and internalising domains. At each age, the co-occurrence was particularly prevalent for aggression and oppositional and ADHD-related problems, with correlations of around 0.5 in general. Aggression also showed substantial associations with anxiety–depression and other internalizing symptoms (correlations around 0.4). Co-occurrence for self-reported problems was somewhat higher than for parental reports, but we found neither rater differences, nor differences across assessment instruments in co-occurrence patterns. There were large similarities in co-occurrence patterns across the different European countries. Finally, co-occurrence was generally stable across age and sex, and if any change was observed, it indicated stronger correlations when children grew older. We present an online tool to visualise these associations as a function of rater, gender, instrument and cohort. In addition, we present a description of the full EU-ACTION projects, its first results and the future perspectives.

The current gold standard for diagnosis of attention deficit/hyperactivity disorder (ADHD) includes subjective measures, such as clinical interview, observation, and rating scales. The significant heterogeneity of ADHD symptoms represents a challenge for this assessment and could prevent an accurate diagnosis. The aim of this work was to investigate the ability of a multi-domain profile of measures, including blood fatty acid (FA) profiles, neuropsychological measures, and functional measures from near-infrared spectroscopy (fNIRS), to correctly recognize school-aged children with ADHD. To answer this question, we elaborated a supervised machine-learning method to accurately discriminate 22 children with ADHD from 22 children with typical development by means of the proposed profile of measures. To assess the performance of our classifier, we adopted a nested 10-fold cross validation, where the original dataset was split into 10 subsets of equal size, which were used repeatedly for training and testing. Each subset was used once for performance validation. Our method reached a maximum diagnostic accuracy of 81% through the combining of the predictive models trained on neuropsychological, FA profiles, and deoxygenated-hemoglobin features. With respect to the analysis of a single-domain dataset per time, the most discriminant neuropsychological features were measures of vigilance, focused and sustained attention, and cognitive flexibility; the most discriminating blood FAs were linoleic acid and the total amount of polyunsaturated fatty acids. Finally, with respect to the fNIRS data, we found a significant advantage of the deoxygenated-hemoglobin over the oxygenated-hemoglobin data in terms of predictive accuracy. These preliminary findings show the feasibility and applicability of our machine-learning method in correctly identifying children with ADHD based on multi-domain data. The present machine-learning classification approach might be helpful for supporting the clinical practice of diagnosing ADHD, even fostering a computer-aided diagnosis perspective.

The present study confirms that children with ADHD display abnormal fatty acid profiles within an Italian setting. Furthermore, PUFAs were associated with behavior but not with cognition. Accordingly, for the first time, lower blood levels of PUFA were associated not only with symptoms of ADHD but also with a poorer quality of life.

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Over the last 15 years, considerable interest has been given to the potential role of omega-3 polyunsaturated fatty acids (PUFAs) for understanding pathogenesis and treatment of neurodevelopmental and psychiatric disorders. This review aims to systematically investigate the scientific evidence supporting the hypothesis on the omega-3 PUFAs deficit as a risk factor shared by different pediatric neuropsychiatric disorders. Medline PubMed database was searched for studies examining blood docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) status in children with neuropsychiatric disorders. Forty-one published manuscripts were compatible with the search criteria. The majority of studies on attention-deficit/hyperactivity disorder (ADHD) and autism found a significant decrease in DHA levels in patients versus healthy controls. For the other conditions examined-depression, juvenile bipolar disorder, intellectual disabilities, learning difficulties, and eating disorders (EDs)-the literature was too limited to draw any stable conclusions. However, except EDs, findings in these conditions were in line with results from ADHD and autism studies. Results about EPA levels were too inconsistent to conclude that EPA could be associated with any of the conditions examined. Finally, correlational data provided, on one hand, evidence for a negative association between DHA and symptomatology, whereas on the other hand, evidence for a positive association between EPA and emotional well-being. Although the present review underlines the potential involvement of omega-3 PUFAs in the predisposition to childhood neuropsychiatric disorders, more observational and intervention studies across different diagnoses are needed, which should integrate the collection of baseline PUFA levels with their potential genetic and environmental influencing factors.

Motor abnormalities are highly prevalent in children with autism spectrum disorder and are strongly predictive of adaptive functioning. Despite the documented sex bias in the prevalence of the disorder, the impact of sex differences on motor abnormalities has been overlooked. The goal of this study was to investigate differences in the motor profile of boys and girls with autism spectrum disorder aged 3–11 years using a multimethod approach. Ninety-eight children with autism spectrum disorder and 98 typically developing children were assessed using the Movement Assessment Battery for Children 2, the Developmental Coordination Disorder Questionnaire, and the kinematic analysis of a reach-to-drop task. Results from principal components analysis on reach-to-drop-dependent measures indicated four components, accounting for kinematic parameters of the motor task. Irrespective of sex, children with autism spectrum disorder showed worse scores on Movement Assessment Battery for Children 2 and Developmental Coordination Disorder Questionnaire subscales than typically developing children. Interestingly, a diagnosis-by-sex interaction was found on a kinematic feature measured in the last part of the movement, with girls with autism spectrum disorder presenting altered motor anticipation. Although preliminary, these findings suggested that sex-related nuances in motor functioning of children with autism spectrum disorder could be insufficiently captured by existing motor measures. Lay abstract Motor peculiarities are often reported in children with autism spectrum disorder and may predict subsequent adaptive functioning and quality of life. Although the sex bias in the prevalence of the disorder is well documented, little is known about differences in motor profile in males and females with autism spectrum disorder. Our goal was to study differences in motor functioning of boys and girls with autism spectrum disorder aged 3–11 years compared with typically developing children. Their motor performances were evaluated using a multimethod approach, including standardized motor tests, caregiver reports, and a detailed motion capture analysis of a simple reach-to-drop movement. We found that, irrespective of sex, children with autism spectrum disorder had worse scores than typically developing children on standardized tests and on caregiver reports. Interestingly, girls with autism spectrum disorder, but not boys, presented altered motor anticipation in reach-to-drop. Our findings emphasize the need for more sex-specific assessment of motor function in autism spectrum disorder.

Metabolomics is an expanding discipline in biology. It is the process of portraying the phenotype of a cell, tissue or species organism using a comprehensive set of metabolites. Therefore, it is of interest to understand complex systems such as metabolomics using a scale-free topology. Genetic networks and the World Wide Web (WWW) are described as networks with complex topology. Several large networks have vertex connectivity that goes beyond a scale-free power-law distribution. It is observed that (a) networks expand constantly by the addition of recent vertices, and (b) recent vertices attach preferentially to sites that are already well connected. Scalefree networks are determined with precision using vital features such as a structure, a disease and a patient. This is pertinent to the understanding of complex systems such as metabolomics. Hence, we describe the relevance of scale-free networks in the understanding of metabolomics in this article.

This single-arm, open-label study aimed to investigate the efficacy of a cognitive-behavioural group training based on acceptance and commitment therapy (ACT) on cognition in drug-naïve children with attention deficit hyperactivity disorder (ADHD). Thirty-six children with ADHD aged 8–13 were invited to participate in the 9-month ACT training programme, which consisted of 26 weekly sessions of group therapy lasting 90 min each. Their parents also received 12 sessions of ACT-based parent training, every 2 weeks. The outcome measure for the present study was the change in the cognitive performance assessed by a battery of computerised task. The cognitive outcome of children receiving ACT-group intervention was compared to that of an external untreated control group of children with ADHD. No significant improvements were observed in any of the cognitive measures. This preliminary study suggests that the 9-month ACT-group training programme might not have positive effects on cognitive difficulties usually occurring in ADHD. Future randomised controlled trials with larger sample sizes are required to shed more light on this issue.