Pervasive alterations of intra-axonal volume and network organization in young children with a 16p11.2 deletion.

Reciprocal Copy Number Variants (CNVs) at the 16p11.2 locus confer high risk for autism spectrum disorder (ASD) and other neurodevelopmental disorders (NDDs). Morphometric MRI studies have revealed large and pervasive volumetric alterations in carriers of a 16p11.2 deletion. However, the specific neuroanatomical mechanisms underlying such alterations, as well as their developmental trajectory, are still poorly understood. Here we explored differences in microstructural brain connectivity between 24 children carrying a 16p11.2 deletion and 66 typically developing (TD) children between 2 and 8 years of age. We found a large pervasive increase of intra-axonal volume widespread over a high number of white matter tracts. Such microstructural alterations in 16p11.2 deletion children were already present at an early age, and led to significant changes in the global efficiency and integration of brain networks mainly associated to language, motricity and socio-emotional behavior, although the widespread pattern made it unlikely to represent direct functional correlates. Our results shed light on the neuroanatomical basis of the previously reported increase of white matter volume, and align well with analogous evidence of altered axonal diameter and synaptic function in 16p11.2 mice models. We provide evidence of a prevalent mechanistic deviation from typical maturation of brain structural connectivity associated with a specific biological risk to develop ASD. Future work is warranted to determine how this deviation contributes to the emergence of symptoms observed in young children diagnosed with ASD and other NDDs.

De novo variants in CACNA1E found in patients with intellectual disability, developmental regression and social cognition deficit but no seizures.

BACKGROUND: De novo variants in the voltage-gated calcium channel subunit α1 E gene (CACNA1E) have been described as causative of epileptic encephalopathy with contractures, macrocephaly and dyskinesias. METHODS: Following the observation of an index patient with developmental delay and autism spectrum disorder (ASD) without seizures who had a de novo deleterious CACNA1E variant, we screened GeneMatcher for other individuals with CACNA1E variants and neurodevelopmental phenotypes without epilepsy. The spectrum of pathogenic CACNA1E variants was compared to the mutational landscape of variants in the gnomAD control population database. RESULTS: We identified seven unrelated individuals with intellectual disability, developmental regression and ASD-like behavioral profile, and notably without epilepsy, who had de novo heterozygous putatively pathogenic variants in CACNA1E. Age of onset of clinical manifestation, presence or absence of regression and degree of severity were variable, and no clear-cut genotype-phenotype association could be recognized. The analysis of disease-associated variants and their comparison to benign variants from the control population allowed for the identification of regions in the CACNA1E protein that seem to be intolerant to substitutions and thus more likely to harbor pathogenic variants. As in a few reported cases with CACNA1E variants and epilepsy, one patient showed a positive clinical behavioral response to topiramate, a specific calcium channel modulator. LIMITATIONS: The significance of our study is limited by the absence of functional experiments of the effect of identified variants, the small sample size and the lack of systematic ASD assessment in all participants. Moreover, topiramate was given to one patient only and for a short period of time. CONCLUSIONS: Our results indicate that CACNA1E variants may result in neurodevelopmental disorders without epilepsy and expand the mutational and phenotypic spectrum of this gene. CACNA1E deserves to be included in gene panels for non-specific developmental disorders, including ASD, and not limited to patients with seizures, to improve diagnostic recognition and explore the possible efficacy of topiramate.

[Complex situations in adults with severe intellectual disabilities - A new support model]. / Situations complexes chez l'adulte avec déficience intellectuelle sévère - Un nouveau modèle d'accompagnement.

Challenging behaviors constitute a real pitfall in supporting people with severe intellectual disabilities. Undermining patients and host institutions as well as psychiatric services, these crisis situations are usually underpinned by many factors including somatic, psychiatric, educational and environmental factors. New models, including the one developed by our team in Lausanne, offer a more specific approach for these complex cases, involving individualized, collaborative and multidisciplinary care to resolve the crisis but also for the overall improvement of the person's life course. This article aims to present the model set up by the Psychiatry Department of the CHUV (UPCHM unit).

Les comportements défis constituent un réel challenge dans l'accompagnement des personnes ayant une déficience intellectuelle sévère, pouvant mettre en grande difficulté les individus, les institutions et les services de psychiatrie. Ces situations de crise sont habituellement sous-tendues par de nombreux facteurs (somatiques, psychiatriques, éducatifs et environnementaux). De nouveaux modèles proposent une approche plus spécifique de ces cas complexes impliquant un abord individualisé, collaboratif et pluridisciplinaire pour résoudre la crise mais également pour améliorer globalement le parcours de vie de la personne. Cet article se propose de présenter le modèle mis en place par notre équipe dans le Département de psychiatrie du CHUV (Unité psychiatrique de crise dévolue au handicap mental, UPCHM).

Sex differences in sensory processing in children with autism spectrum disorder.

Despite the high prevalence of sensory processing difficulties in children with autism spectrum disorder (ASD), little research has focused on the sex differences in sensory processing. Furthermore, there is a lack of knowledge on the female-specific symptoms of ASD, contributing to later referral, diagnosis and intervention. In this study, we examined the sex differences in sensory processing symptoms in large cohorts of ASD children (N = 168; 26 females, 142 males) and typically developing (TD) children (N = 439; 209 females, 230 males). For this, we translated the sensory processing measure (SPM) and SPM - Preschool (SPM-P) Home Forms to French. The SPM/SPM-P are parent/caregiver questionnaires that assess typical behavioral responses to sensory stimuli. Overall, our results showed that the magnitude of the differences in sensory processing between males and females is larger in ASD children relative to TD children, with females showing more severe symptoms in Hearing, as well as Balance and Motion subscales. Additionally, linear discriminant analysis showed that the SPM/SPM-P are good at discriminating TD children from ASD, children with higher accuracy rates for females than for males. These findings are discussed in light of the heterogeneity of sensory processing difficulties present in ASD. Overall, our results suggest that there seem to be female-specific profiles in sensory processing difficulties in ASD. Implications of findings concerning sex differences in sensory processing and their potential for improving identification and diagnosis of ASD females are discussed. LAY SUMMARY: The present study examined sex differences in behavioral responses to sensory stimuli in children with autism spectrum disorder (ASD), and typically developing (TD) children. While there is a small trend for TD males to show more sensory processing atypicalities, female ASD children show significantly more atypical responses compared to their male counterparts. This has important implications for characterizing female autism profiles, and ultimately improving the chance for earlier detection, diagnosis and treatment.

Considerations and Perspectives on Interventions to Improve Social Cognition in Adolescents With ASD Without ID: Involving Parents in Social Skills Groups.

Improving social cognition and social skills is a challenge faced by individuals with Autism Spectrum Disorder without Intellectual Disability at any age. This process is particularly critical during late adolescence (15-18 years), a developmental phase generally characterized by rich social experiences that usually foster the development of friendships. Nevertheless, for youth with ASD, lingering difficulties in social cognition often hinder their ability to generate responses considered socially appropriated. These social deficits can contribute to isolation that has a detrimental effect on mental health. In adulthood, deficits of social skills are strongly associated with an overall lack of support, characterized by a failure to integrate into the labor market, a high unemployment rate, social isolation, and a higher suicide rate. In clinical settings, social skills groups are well-established therapeutic means to improve social cognition and social skills. Nevertheless, these interventions vary greatly regarding their objectives, contents and duration. Moreover, few have been validated and replicated by research. Our aim is to bring certain perspectives to a type of intervention that are widely used in care settings. After reviewing its positive aspects for increasing social cognition, and its limitations, we will discuss strategies to facilitate the generalization of social skills in an ecological context. In particular, we will base our reflection on our clinical experience and on our current project to adapt the PEERS model for adolescents into French. We will consider the current trend of involving parents as "social coaches" to generalize the social knowledge acquired in the social skills groups.

Touch and olfaction/taste differentiate children carrying a 16p11.2 deletion from children with ASD.

BACKGROUND: Sensory processing atypicalities are frequent in Autism Spectrum Disorder (ASD) and neurodevelopmental disorders (NDD). Different domains of sensory processing appear to be differentially altered in these disorders. In this study, we explored the sensory profile of two clinical cohorts, in comparison with a sample of typically developing children. METHODS: Behavioral responses to sensory stimuli were assessed using the Sensory Processing Measure (parent-report questionnaire). We included 121 ASD children, 17 carriers of the 16p11.2 deletion (Del 16p11.2) and 45 typically developing (TD) children. All participants were aged between 2 and 12 years. Additional measures included the Tactile Defensiveness and Discrimination Test-Revised, Wechsler Intelligence Scales and Autism Diagnostic Observation Schedule (ADOS-2). Statistical analyses included MANCOVA and regression analyses. RESULTS: ASD children score significantly higher on all SPM subscales compared to TD. Del16p11.2 also scored higher than TD on all subscales except for tactile and olfactory/taste processing, in which they score similarly to TD. When assessing sensory modulation patterns (hyper-, hypo-responsiveness and seeking), ASD did not significantly differ from del16p11.2. Both groups had significantly higher scores across all patterns than the TD group. There was no significant association between the SPM Touch subscale and the TDDT-R. LIMITATIONS: Sensory processing was assessed using a parent-report questionnaire. Even though it captures observable behavior, a questionnaire does not assess sensory processing in all its complexity. The sample size of the genetic cohort and the small subset of ASD children with TDDT-R data render some of our results exploratory. Divergence between SPM Touch and TDDT-R raises important questions about the nature of the process that is assessed. CONCLUSIONS: Touch and olfaction/taste seem to be particularly affected in ASD children compared to del16p11.2. These results indicate that parent report measures can provide a useful perspective on behavioral expression. Sensory phenotyping, when combined with neurobiological and psychophysical methods, might have the potential to provide a better understanding of the sensory processing in ASD and in other NDD.

Cancer Care of Children, Adolescents and Adults With Autism Spectrum Disorders: Key Information and Strategies for Oncology Teams.

Delivering optimal cancer care to children, adolescents and adults with ASD has recently become a healthcare priority and represents a major challenge for all providers involved. In this review, and after consideration of the available evidence, we concisely deliver key information on this heterogenous group of neurodevelopmental disorders, as well as recommendations and concrete tools for the enhanced oncological care of this vulnerable population of patients.

[Autism spectrum disorder : a diagnosis for a better support]. / Diagnostic des troubles du spectre autistique, un enjeu pour un meilleur accompagnement des personnes.

Autism spectrum disorders (ASD) are neurodevelopmental disorders at the origin of severe handicap. The clinical expression of these disorders is strongly variable according to the presence of an intellectual deficiency or an associated organic and\or psychiatric disorder. Getting a correct diagnosis of ASD as a child or an adult can help a person and the professionals understand past difficulties, identify his or her strengths, and adapt the right kind of help. A complete diagnosis, realized by a trained multidisciplinary team, allows to define the necessary strategies of global support, in partnership with families. Treatments and services can improve a person's symptoms and ability to function. These characteristics must be regularly assessed in time.

Les troubles du spectre autistique (TSA) sont des troubles neurodéveloppementaux à l'origine d'un handicap le plus souvent sévère. L'expression clinique de ces troubles est très variable en fonction de l'existence d'une déficience intellectuelle ou d'un trouble organique et / ou psychiatrique associé. Les professionnels de santé doivent être sensibilisés aux signes cliniques évocateurs de TSA chez l'enfant et l'adulte afin d'orienter au mieux les familles. Le bilan diagnostique complet, réalisé par une équipe pluridisciplinaire formée, permet de définir les stratégies d'accompagnement adaptées en accord avec les bonnes pratiques cliniques, en partenariat avec les familles. Un programme individualisé, spécifique à la personne, repose sur l'identification des compétences et besoins. Ces caractéristiques doivent être réévaluées régulièrement au cours du temps.

Atypical coordination of cortical oscillations in response to speech in autism.

Subjects with autism often show language difficulties, but it is unclear how they relate to neurophysiological anomalies of cortical speech processing. We used combined EEG and fMRI in 13 subjects with autism and 13 control participants and show that in autism, gamma and theta cortical activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations, and to down-regulate gamma oscillations in the group with autism. This deficit predicts the severity of both verbal impairment and autism symptoms in the affected sample. Finally, we found that oscillation-based connectivity between auditory and other language cortices is altered in autism. These results suggest that the verbal disorder in autism could be associated with an altered balance of slow and fast auditory oscillations, and that this anomaly could compromise the mapping between sensory input and higher-level cognitive representations.

The French version of the autism-spectrum quotient in adolescents: a cross-cultural validation study.

We assessed the accuracy of the French version of the Autism Spectrum Quotient (AQ) in adolescents with Asperger syndrome (AS) and high-functioning autism (HFA) compared to healthy controls and adolescents with psychiatric disorders (PDs). Three groups of adolescents, aged 11-18, were assessed: 116 with AS/HFA (93 with IQ ≥ 85 and 20 with 70 ≤ IQ < 85), 39 with other PDs, and 199 healthy controls. The AS/HFA group scored significantly higher than the healthy control and PD groups. A cut-off score of 26 was used to differentiate the autism group from healthy controls with 0.89 sensitivity and 0.98 specificity. Scores did not vary by age or sex.

Feature selection and classification of imbalanced datasets: application to PET images of children with autistic spectrum disorders.

Learning with discriminative methods is generally based on minimizing the misclassification of training samples, which may be unsuitable for imbalanced datasets where the recognition might be biased in favor of the most numerous class. This problem can be addressed with a generative approach, which typically requires more parameters to be determined leading to reduced performances in high dimension. In such situations, dimension reduction becomes a crucial issue. We propose a feature selection/classification algorithm based on generative methods in order to predict the clinical status of a highly imbalanced dataset made of PET scans of forty-five low-functioning children with autism spectrum disorders (ASD) and thirteen non-ASD low functioning children. ASDs are typically characterized by impaired social interaction, narrow interests, and repetitive behaviors, with a high variability in expression and severity. The numerous findings revealed by brain imaging studies suggest that ASD is associated with a complex and distributed pattern of abnormalities that makes the identification of a shared and common neuroimaging profile a difficult task. In this context, our goal is to identify the rest functional brain imaging abnormalities pattern associated with ASD and to validate its efficiency in individual classification. The proposed feature selection algorithm detected a characteristic pattern in the ASD group that included a hypoperfusion in the right Superior Temporal Sulcus (STS) and a hyperperfusion in the contralateral postcentral area. Our algorithm allowed for a significantly accurate (88%), sensitive (91%) and specific (77%) prediction of clinical category. For this imbalanced dataset, with only 13 control scans, the proposed generative algorithm outperformed other state-of-the-art discriminant methods. The high predictive power of the characteristic pattern, which has been automatically identified on whole brains without any priors, confirms previous findings concerning the role of STS in ASD. This work offers exciting possibilities for early autism detection and/or the evaluation of treatment response in individual patients.

Autism in three patients with cystic or hyperechogenic kidneys and chromosome 17q12 deletion.

BACKGROUND: We report autism in 3 out of 53 children with cystic or hyperechogenic kidneys and heterozygous 17q12 region deletion encompassing hepatocyte nuclear factor-1beta (HNF1B). RESULTS: They presented mental retardation, social interaction impairments, verbal and non-verbal communication deficits and stereotyped behaviours. Deletion size and location of breakpoints were similar to those reported in patients with renal disease/diabetes only. CONCLUSION: Reciprocal genomic rearrangements of the 17q12 region, reported in patients with mental retardation and epilepsy, could also be involved in autism. Nephrologists should be aware of the possibility of autism in patients with 17q12 deletion including HNF1B locus.

MRI findings in 77 children with non-syndromic autistic disorder.

BACKGROUND: The clinical relevance of MR scanning in children with autism is still an open question and must be considered in light of the evolution of this technology. MRI was judged to be of insufficient value to be included in the standard clinical evaluation of autism according to the guidelines of the American Academy of Neurology and Child Neurology Society in 2000. However, this statement was based on results obtained from small samples of patients and, more importantly, included mostly insufficient MRI sequences. Our main objective was to evaluate the prevalence of brain abnormalities in a large group of children with a non-syndromic autistic disorder (AD) using T1, T2 and FLAIR MRI sequences. METHODOLOGY: MRI inspection of 77 children and adolescents with non-syndromic AD (mean age 7.4+/-3.6) was performed. All met the DSM-IV and ADI -R criteria for autism. Based on recommended clinical and biological screenings, we excluded patients with infectious, metabolic or genetic diseases, seizures or any other neurological symptoms. Identical MRI inspections of 77 children (mean age 7.0+/-4.2) without AD, developmental or neurological disorders were also performed. All MRIs were acquired with a 1.5-T Signa GE (3-D T1-FSPGR, T2, FLAIR coronal and axial sequences). Two neuroradiologists independently inspected cortical and sub-cortical regions. MRIs were reported to be normal, abnormal or uninterpretable. PRINCIPAL FINDINGS: MRIs were judged as uninterpretable in 10% (8/77) of the cases. In 48% of the children (33/69 patients), abnormalities were reported. Three predominant abnormalities were observed, including white matter signal abnormalities (19/69), major dilated Virchow-Robin spaces (12/69) and temporal lobe abnormalities (20/69). In all, 52% of the MRIs were interpreted as normal (36/69 patients). CONCLUSIONS: An unexpectedly high rate of MRI abnormalities was found in the first large series of clinical MRI investigations in non-syndromic autism. These results could contribute to further etiopathogenetic research into autism.

Four-factor structure of obsessive-compulsive disorder symptoms in children, adolescents, and adults.

OBJECTIVE: To determine whether the four-factor category-based obsessive-compulsive disorder (OCD) symptom structure from a previous confirmatory factor analysis (CFA) may be appropriately used in child, adolescent, and adult groups. Symptom dimensions are increasingly used as quantitative traits in genetic, neuroimaging, and treatment studies of OCD across all ages. Identification of a category-based OCD symptom dimension structure that is validated for use across child, adolescent, and adult age groups is necessary to guide ongoing translational research. METHOD: Four OCD samples comprising 356 individuals were divided into child, adolescent, and adult groups. The fit of the only CFA-defined four-factor model was compared across these independent age group samples. Multiple-group CFA using maximum likelihood estimation assessed adequacy of fit comparing unconstrained and measurement weight-constrained models. The fit of previous exploratory factor analysis-defined three- and five-factor models on adults was also examined using CFA. RESULTS: A four-factor solution provided adequate but imperfect fit across age groups, with comparable indices to the only previous OCD CFA: factor 1 (aggressive/sexual/religious/somatic/checking); factor 2 (symmetry/ordering/counting/repeating); factor 3 (contamination/cleaning), and factor 4 (hoarding). Models in which factor loadings were constrained and unconstrained across the three age groups yielded comparable model fit. Factors were highly correlated and were not mutually exclusive. The four-factor solution provided an improved fit to both three- and five-factor solutions using CFA across the three age groups. CONCLUSIONS: A four-factor, CFA-defined, category-based model of OCD symptom dimensions is adequate for use in children, adolescents, and adult age groups. The factor structure of this multiple age group sample has limitations and is imperfect, but current findings support the comparability of the defined latent OCD dimensions across age groups. Further work is needed to optimize a comprehensive symptom dimension model reflecting clinical heterogeneity for use in emergent translational studies.

Association of the SLC1A1 glutamate transporter gene and obsessive-compulsive disorder.

CONTEXT: Obsessive-Compulsive Disorder (OCD) is a debilitating illness with putative glutamatergic abnormalities. Two separate proximal haplotypes in the glutamate transporter gene, SLC1A1, were recently reported to be associated with OCD among males, but replication is required. OBJECTIVES: This study examines SLC1A1 as a candidate gene for OCD and explores gender influences. It was hypothesized that a significant association between SLC1A1 and OCD would be replicated in an independent sample of males but not females. DESIGN: Family-based association candidate gene study. SETTING: Participants were recruited from tertiary care OCD specialty clinics. PARTICIPANTS: OCD probands and their first degree relatives. MAIN OUTCOMES MEASURES: Association of OCD with genotypes of single nucleotide polymorphism (SNP) markers and related haplotypes. RESULTS: Association between OCD and the three-marker haplotype rs12682807/ rs2072657/ rs301430, with overtransmission of A/T/T, was observed in both genders combined (global P = 0.0015) and in males (global P = 0.0031). Single-marker associations with OCD in the region (rs3780412 and rs2228622) demonstrated modest significance (permuted P = 0.045). CONCLUSIONS: This study identifies a significant association between the SLC1A1 glutamate transporter gene and OCD in a haplotype overlapping with that recently reported.

[Obsessive-compulsive disorder in children and adolescents]. / Le trouble obsessionnel compulsif chez l'enfant et l'adolescent.

Obsessive compulsive disorder (OCD) involves obsessions and compulsions that cause impairment and distress, and which interfere with children's developmental adaptation, daily functioning. Further more, OCD often disrupts peer and family relationships and school performance. One considered rare, recent epidemiological studies report prevalence rates ranging from 1% in prepubertal children to 3% in adolescents. Recently, significant advances have been made in understanding of the aetiology, pathophysiology, phenomenology, and treatment in children. The ongoing refinement of cognitive-behaviour and pharmacological treatment approaches has increased the likelihood that many youngsters with OCD will lead satisfying and relatively normal lives.

A genetic family-based association study of OLIG2 in obsessive-compulsive disorder.

CONTEXT: Obsessive-compulsive disorder (OCD) is a debilitating familial psychiatric illness with associated brain abnormalities in the white matter. The gene for oligodendrocyte lineage transcription factor 2 (OLIG2) is an essential regulator in the development of cells that produce white matter (myelin). The OLIG2 gene is also highly expressed in brain regions implicated in OCD. OBJECTIVES: To examine OLIG2 as a candidate gene for OCD susceptibility and to explore whether comorbidity subtypes of OCD have distinct associations with OLIG2 and the functionally related OLIG1 gene. It was hypothesized a priori that OLIG2 and OLIG1 were associated with OCD regardless of the presence of comorbid Tourette disorder (TD), but not with TD alone. DESIGN: Family-based association candidate gene study. SETTING: Participants and their family members were recruited from tertiary care OCD and TD specialty clinics. PARTICIPANTS: Families of 66 probands with OCD with and without TD and 31 probands with TD without OCD. MAIN OUTCOME MEASURES: Genotypes of single nucleotide polymorphism markers and related haplotypes. RESULTS: The following 3 single nucleotide polymorphism markers on OLIG2 were associated with the OCD without TD phenotype: rs762178 (minor allele frequency, 35%; P<.001), rs1059004 (minor allele frequency, 44%; P = .005), and rs9653711 (minor allele frequency, 44%; P = .004). A 5-marker haplotype (A/C/T/T/G) constituting these single nucleotide polymorphisms and exonic single nucleotide polymorphisms rs6517137 and rs13046814 was undertransmitted (frequency, 32%; permuted P=.004), whereas the G/A/T/T/C haplotype (frequency, 22%; permuted P=.02) was overtransmitted to probands with OCD alone, with a significant global P value (permuted P=.008). CONCLUSIONS: This is the first study reporting an association between OLIG2 and OCD, specifically when TD comorbidity is absent. The findings support a role for white matter abnormalities in the etiology of the disorder.

Mutations in the gene encoding the synaptic scaffolding protein SHANK3 are associated with autism spectrum disorders.

SHANK3 (also known as ProSAP2) regulates the structural organization of dendritic spines and is a binding partner of neuroligins; genes encoding neuroligins are mutated in autism and Asperger syndrome. Here, we report that a mutation of a single copy of SHANK3 on chromosome 22q13 can result in language and/or social communication disorders. These mutations concern only a small number of individuals, but they shed light on one gene dosage-sensitive synaptic pathway that is involved in autism spectrum disorders.

Autism, the superior temporal sulcus and social perception.

The most common clinical sign of autism spectrum disorders (ASD) is social interaction impairment, which is associated with communication deficits and stereotyped behaviors. Based on recent brain-imaging results, our hypothesis is that abnormalities in the superior temporal sulcus (STS) are highly implicated in ASD. STS abnormalities are characterized by decreased gray matter concentration, rest hypoperfusion and abnormal activation during social tasks. STS anatomical and functional anomalies occurring during early brain development could constitute the first step in the cascade of neural dysfunction underlying ASD. We will focus this review on the STS, which has been highly implicated in social cognition. We will review recent data on the contribution of the STS to normal social cognition and review brain-imaging data implicating this area in ASD. This review is part of the INMED/TINS special issue "Nature and nurture in brain development and neurological disorders", based on presentations at the annual INMED/TINS symposium (http://inmednet.com/).

Exploratory analysis of obsessive compulsive symptom dimensions in children and adolescents: a prospective follow-up study.

BACKGROUND: Recent statistical approaches based on factor analysis of obsessive compulsive (OC) symptoms in adult patients have identified dimensions that seem more effective in symptom-based taxonomies and appear to be more stable over time. Although a phenotypic continuum from childhood to adulthood has been hypothesized, no factor analytic studies have been performed in juvenile patients, and the stability of OC dimensions in children and adolescents has not been assessed. METHODS: This study was designed to perform an exploratory factor analysis of OC symptoms in a sample of children and adolescents with OC disorder (OCD) and to investigate the course of factors over time (mean follow-up period: four years). RESULTS: We report for the first time that four symptom dimensions, remarkably similar to those previously described in adults, underlined the heterogeneity of OC symptoms in children and adolescents. Moreover, after follow-up, the symptom dimensions identified remained essentially unmodified. The changes observed concerned the intensity of dimensions rather than shifts from one dimension to another. CONCLUSION: These findings reinforce the hypothesis of a phenotypic continuum of OC symptoms from childhood to adulthood. They also strengthen the interest for investigating the clinical, neurobiological and genetic heterogeneity of OCD using a dimension-based approach.