A longitudinal comparison of emotional, behavioral and attention problems in autistic and typically developing children

BACKGROUND

Mental health problems are elevated in autistic individuals but there is limited evidence on the developmental course of problems across childhood. We compare the level and growth of anxious-depressed, behavioral and attention problems in an autistic and typically developing (TD) cohort.

METHODS

Latent growth curve models were applied to repeated parent-report Child Behavior Checklist data from age 2-10 years in an inception cohort of autistic children (Pathways, N = 397; 84% boys) and a general population TD cohort (Wirral Child Health and Development Study; WCHADS; N = 884, 49% boys). Percentile plots were generated to quantify the differences between autistic and TD children.

RESULTS

Autistic children showed elevated levels of mental health problems, but this was substantially reduced by accounting for IQ and sex differences between the autistic and TD samples. There was small differences in growth patterns; anxious-depressed problems were particularly elevated at preschool and attention problems at late childhood. Higher family income predicted lower base-level on all three dimensions, but steeper increase of anxious-depressed problems. Higher IQ predicted lower level of attention problems and faster decline over childhood. Female sex predicted higher level of anxious-depressed and faster decline in behavioral problems. Social-affect autism symptom severity predicted elevated level of attention problems. Autistic girls' problems were particularly elevated relative to their same-sex non-autistic peers.

CONCLUSIONS

Autistic children, and especially girls, show elevated mental health problems compared to TD children and there are some differences in predictors. Assessment of mental health should be integrated into clinical practice for autistic children.

Non-verbal IQ and change in restricted and repetitive behavior throughout childhood in autism: a longitudinal study using the Autism Diagnostic Interview-Revised

BACKGROUND

Restricted and repetitive behavior (RRB) is one of the characteristic features of Autism Spectrum Disorder. This domain of symptoms includes a broad range of behaviors. There is a need to study each behavior individually to better understand the role of each in the development of autistic children. Moreover, there are currently no longitudinal studies investigating change in these behaviors over development.

METHODS

The goal of the present study was to explore the association between age and non-verbal IQ (NVIQ) on 15 RRB symptoms included in the Autism Diagnostic Interview-Revised (ADI-R) over time. A total of 205 children with ASD were assessed using the ADI-R at time of diagnosis, at age 6 years, and at age 11 years, and with the Wechsler Intelligence Scales for Children-Fourth Edition (WISC-IV) at age 8 years.

RESULTS

The proportion of children showing each RRB tended to diminish with increasing age, except for sensitivity to noise and circumscribed interests, where the proportion increased over time. Although there was no significant main effect of NVIQ, there was a significant interaction between age and NVIQ. This was mainly driven by Difficulties with change in routine, for which higher NVIQ was associated with the behavior remaining relatively stable with age, while lower NVIQ was associated with the behavior becoming more prevalent with age.

LIMITATIONS

The study focused on the presence/absence of each RRB but did not account for potential changes in frequency or severity of the behaviors over development. Furthermore, some limitations are inherent to the measures used. The ADI-R relies on parent report and hence has some level of subjectivity, while the Wechsler intelligence scales can underestimate the intellectual abilities of some autistic children.

CONCLUSIONS

These results confirm that specific RRB are differentially linked to age and NVIQ. Studying RRB individually is a promising approach to better understanding how RRB change over the development of autistic children and are linked to other developmental domains.

Genome-wide association study of emotional empathy in children

The genetic contribution to different aspects of empathy is now established, although the exact loci are unknown. We undertook a genome-wide association study of emotional empathy (EE) as measured by emotion recognition skills in 4,780 8-year old children from the ALSPAC cohort who were genotyped and imputed to Phase 1 version 3 of the 1000 Genomes Project. We failed to find any genome-wide significant signal in either our unstratified analysis or analysis stratified according to sex. A gene-based association analysis similarly failed to find any significant loci. In contrast, our transcriptome-wide association study (TWAS) with a whole blood reference panel identified two significant loci in the unstratified analysis, residualised for the effects of age, sex and IQ. One signal was for CD93 on chromosome 20; this gene is not strongly expressed in the brain, however. The other signal was for AL118508, a non-protein coding pseudogene, which completely lies within CD93’s genomic coordinates, thereby explaining its signal. Neither are obvious candidates for involvement in the brain processes that underlie emotion recognition and its developmental pathways.

Once and Again: Intergenerational Transmission of Parenting

Introduction

Animal and human studies suggest that individual differences in maternal parenting behaviour are transmitted from one generation to the next.

Objective

This study aimed to examine potential psychosocial mechanisms underlying an intergenerational transmission of conceptualization of parenting, including affect, cognition, and parental support.

Methods

In a subsample of 201 first-time mothers participating in the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project, we assessed maternal childhood rearing experiences, using the Parental Bonding Instrument and the Childhood Trauma Questionnaire. At 6 months postpartum, mothers completed questionnaires on parenting stress, symptoms of depression, internalization of maternal care regulation and current relationship with mother and father.

Results

We found significant direct associations of maltreatment and rearing by the grandmother with parenting stress at 6 months. These associations were mediated through distinct psychosocial pathways: the association of maltreatment on higher parenting stress was fully mediated through more maternal symptoms of depression (z = 2.297; P = 022). The association between sub-optimal rearing provided by the mother and higher parenting stress was mediated through lower internalization of maternal care regulation (z = -2.155; P = 031) and to a lesser degree through more symptoms of depression (z = -1.842; P = 065). Finally, higher quality rearing by the grandfather was indirectly related to lower parenting stress through positive current relationship with the father (z = -2.617; P = 009).

Conclusions

There are distinct pathways by which early experiences manifest in parenting stress. By understanding the structure of dysregulated parenting, clinicians will have practical information to specifically target maternal motivation, social supports, and depressed mood to disrupt maladaptive parenting cognitions and practices.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Examining Trajectories of Daily Living Skills over the Preschool Years for Children with Autism Spectrum Disorder

Preschool children with autism spectrum disorder (ASD) experience slower development of daily living skills (DLS) that are essential for independent functioning compared to typically developing children. Few studies have examined the trajectories of DLS in preschoolers with ASD and the existing literature has reported conflicting results. This study examined DLS trajectories and potential covariates for preschoolers with ASD from a multi-site longitudinal study following children from diagnosis to the end of grade 1. Multi-level modeling was conducted with DLS domain scores from the Vineland Adaptive Behavior Scales-2. The results demonstrated a positive trajectory of increasing scores over time, associations of age of diagnosis, developmental level, stereotypy, and language skills with the mean score at T4 or age 6 years, whereas rate of change was only associated with ASD symptom severity, such that an improvement in DLS trajectory was associated with lower and improving ASD symptom severity.

Functional DNA methylation signatures for autism spectrum disorder genomic risk loci: 16p11.2 deletions and CHD8 variants

Background

Autism spectrum disorder (ASD) is a common and etiologically heterogeneous neurodevelopmental disorder. Although many genetic causes have been identified (> 200 ASD-risk genes), no single gene variant accounts for > 1% of all ASD cases. A role for epigenetic mechanisms in ASD etiology is supported by the fact that many ASD-risk genes function as epigenetic regulators and evidence that epigenetic dysregulation can interrupt normal brain development. Gene-specific DNAm profiles have been shown to assist in the interpretation of variants of unknown significance. Therefore, we investigated the epigenome in patients with ASD or two of the most common genomic variants conferring increased risk for ASD. Genome-wide DNA methylation (DNAm) was assessed using the Illumina Infinium HumanMethylation450 and MethylationEPIC arrays in blood from individuals with ASD of heterogeneous, undefined etiology (n = 52), and individuals with 16p11.2 deletions (16p11.2del, n = 9) or pathogenic variants in the chromatin modifier CHD8 (CHD8^+/−, n = 7).

Results

DNAm patterns did not clearly distinguish heterogeneous ASD cases from controls. However, the homogeneous genetically-defined 16p11.2del and CHD8^+/− subgroups each exhibited unique DNAm signatures that distinguished 16p11.2del or CHD8^+/− individuals from each other and from heterogeneous ASD and control groups with high sensitivity and specificity. These signatures also classified additional 16p11.2del (n = 9) and CHD8 (n = 13) variants as pathogenic or benign. Our findings that DNAm alterations in each signature target unique genes in relevant biological pathways including neural development support their functional relevance. Furthermore, genes identified in our CHD8^+/− DNAm signature in blood overlapped differentially expressed genes in CHD8^+/− human-induced pluripotent cell-derived neurons and cerebral organoids from independent studies.

Conclusions

DNAm signatures can provide clinical utility complementary to next-generation sequencing in the interpretation of variants of unknown significance. Our study constitutes a novel approach for ASD risk-associated molecular classification that elucidates the vital cross-talk between genetics and epigenetics in the etiology of ASD.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0684-3) contains supplementary material, which is available to authorized users.

Service utilization in a sample of preschool children with autism spectrum disorder: A Canadian snapshot

OBJECTIVE

To describe services received by preschool children diagnosed with autism spectrum disorder (ASD) during the five-year period following their diagnosis.

METHOD

An inception cohort of preschoolers diagnosed with ASD from Halifax (Nova Scotia), Montreal (Quebec), Hamilton (Ontario), Edmonton (Alberta) and Vancouver (British Columbia) were invited to participate. Parents/caregivers (n=414) described the services provided to their children at four time points: baseline (T1; within four months of diagnosis; mean age three years); six months later (T2); 12 months later (T3); and at school entry (T4). Data were first coded into 11 service types and subsequently combined into four broader categories (no services, behavioural, developmental and general) for analysis.

RESULTS

More than 80% of children at T1, and almost 95% at T4 received some type of service, with a significant number receiving >1 type of service at each assessment point. At T1, the most common service was developmental (eg, speech-language therapy). Subsequently, the most common services were a combination of behavioural and developmental (eg, intensive therapy based on applied behaviour analysis and speech-language therapy). Service provision varied across provinces and over time.

DISCUSSION

Although most preschool children with ASD residing in urban centres were able to access specialized services shortly after diagnosis, marked variation in services across provinces remains a concern.

The phenotypic manifestations of rare genic CNVs in autism spectrum disorder

Significant evidence exists for the association between copy number variants (CNVs) and Autism Spectrum Disorder (ASD); however, most of this work has focused solely on the diagnosis of ASD. There is limited understanding of the impact of CNVs on the 'sub-phenotypes' of ASD. The objective of this paper is to evaluate associations between CNVs in differentially brain expressed (DBE) genes or genes previously implicated in ASD/intellectual disability (ASD/ID) and specific sub-phenotypes of ASD. The sample consisted of 1590 cases of European ancestry from the Autism Genome Project (AGP) with a diagnosis of an ASD and at least one rare CNV impacting any gene and a core set of phenotypic measures, including symptom severity, language impairments, seizures, gait disturbances, intelligence quotient (IQ) and adaptive function, as well as paternal and maternal age. Classification analyses using a non-parametric recursive partitioning method (random forests) were employed to define sets of phenotypic characteristics that best classify the CNV-defined groups. There was substantial variation in the classification accuracy of the two sets of genes. The best variables for classification were verbal IQ for the ASD/ID genes, paternal age at birth for the DBE genes and adaptive function for de novo CNVs. CNVs in the ASD/ID list were primarily associated with communication and language domains, whereas CNVs in DBE genes were related to broader manifestations of adaptive function. To our knowledge, this is the first study to examine the associations between sub-phenotypes and CNVs genome-wide in ASD. This work highlights the importance of examining the diverse sub-phenotypic manifestations of CNVs in ASD, including the specific features, comorbid conditions and clinical correlates of ASD that comprise underlying characteristics of the disorder.

Clinical assessment of autism in high-risk 18-month-olds

Earlier intervention improves outcomes for children with autism spectrum disorders (ASDs), but existing identification tools are at the limits of standardization with 18-month-olds. We assessed potential behavioural markers of ASD at 18 months in a high-risk cohort of infant siblings of children with ASD. Prospective data were collected using the Autism Diagnostic Observation Schedule (ADOS) and Autism Observation Scale for Infants (AOSI) on 155 infant siblings and 73 low-risk controls at 18 months. Infants were classified into three groups (ASD sibs, non-ASD sibs, controls) based on blind best-estimate diagnosis at age 3. Fisher's exact tests, followed by discriminant function analyses, revealed that the majority of informative ADOS items came from the social and behavioural domains, and AOSI items measuring behavioural reactivity and motor control contributed additional information. Findings highlight the importance of considering not only social-communication deficits, but also basic dimensions of temperament including state regulation and motor control when assessing toddlers with suspected ASD.

An inversion inv(4)(p12-p15.3) in autistic siblings implicates the 4p GABA receptor gene cluster

INTRODUCTION

We describe the case of two brothers diagnosed with autism who both carry a paracentic inversion of the short arm of chromosome 4 (46,XY, inv(4)(p12-p15.3)). We have determined that this inversion is inherited from an apparently unaffected mother and unaffected maternal grandfather. Methods/

RESULTS

Using fluorescence in situ hybridisation analysis and Southern blot hybridisation we identified the breakpoints. The proximal breakpoint (4p12) maps to a region containing a cluster of gamma-aminobutyric acid A (GABA(A)) receptor genes, and directly interrupts the GABRG1 gene, the distal-most gene of the cluster. We also identified an insertion/deletion polymorphism for a approximately 2 kb LINE1 (L1) element that occurs within intron 7 of GABRG1. Our genotype analysis amongst autism families indicated that the L1 deletion allele did not show increased transmission to affected individuals. No linkage disequilibrium was evident between the L1 and single nucleotide polymorphisms in adjacent GABA(A) receptor genes on 4p, where a recent study has identified significant association with autism.

DISCUSSION

Despite this, the identification of an inversion breakpoint disrupting GABRG1 provides solid support for the genetic involvement of the short arm of chromosome 4 in the genetic aetiology of autism, and for the hypothesis of disrupted GABA neurotransmission in autism.

Predictors of outcome among high functioning children with autism and Asperger syndrome

BACKGROUND

The objective of this paper is to assess the extent to which measures of cognitive abilities taken in an inception cohort of young high functioning children with autism and Asperger syndrome predict outcome roughly two and six years later.

METHOD

Children who received a diagnosis of autism or Asperger syndrome (AS) and who had a nonverbal IQ score in the 'non-retarded' range were included in the inception cohort. Measures of language and nonverbal skills were taken when the children were 4-6 years of age and outcome assessments were completed when the children were 6-8 and 10-13 years of age. The three outcome measures consisted of scales of adaptive behaviours in socialisation and communication and a composite measure of autistic symptoms (abnormal language, abnormal body and object use, difficulties relating to others, sensory issues and social and self-help difficulties).

RESULTS

The explanatory power of the predictor variables was greater for communication and social skills than for autistic symptoms. The power of prediction was stable over time but did differ by PDD subtype. In general, the association between language skills and outcome was stronger in the autism group than in the AS group.

CONCLUSIONS

These results support the emphasis of early intervention programmes on language but more work needs to be done on understanding variables that influence outcome in social skills and autistic behaviours, particularly in those with AS.

Birth order effects on nonverbal IQ scores in autism multiplex families

Lord (1992) published a brief report showing a trend for decreasing nonverbal IQ scores with increasing birth order in a sample of 16 autism multiplex families, and urged replication in a larger sample. In this report, analyses of nonverbal IQ scores for a sample of 144 autism multiplex families indicated that nonverbal IQ scores were significantly lower in secondborn compared with firstborn siblings with autism. This birth order effect was independent of gender as well as the age differences within sib pairs. No such birth order effects were found for social or communicative deficits as measured by the Autism Diagnostic Interview-Revised (ADI-R), but there was a modest tendency for increased scores for ritualistic behaviors for the firstborn sibs. Further, there were no gender differences on nonverbal IQ scores in this sample. Results are discussed in terms of implications for genetic studies of autism.

Familial influences on substance use by adolescents and young adults

This study uses data from the Ontario Health Survey to examine within-family influences (sibship number, age and sex composition; family structure and parental substance use) on the use of tobacco, alcohol and marijuana in households (N = 4,643) among offspring aged 12 to 24 years. Using a modification of the kappa statistic, concordance among siblings is modest generally and undifferentiated across substance type. Concordance is stronger among sibships that are either all male or older (19-24 years) and is particularly strong for siblings < or = two years apart in age. The dominant influence of substance use behaviour appears to be from older siblings to younger siblings and not from parents to offspring. Sibling concordance for substance use suggests that the treatment and prevention of substance use (and abuse) among adolescents and young adults might be enhanced by including a family focus, especially where there are two or more siblings at home.

Two-year outcome of preschool children with autism or Asperger's syndrome

OBJECTIVE

DSM-IV specifies that Asperger's disorder is a type of pervasive developmental disorder without clinically significant cognitive or language delay. There are no data, however, on the outcome of children with Asperger's disorder or on whether their outcome differs from that of children with autism. The objectives of this study were to compare the outcome of groups of children with these disorders over a period of 2 years on variables independent of the defining criteria and to identify variables that might account for these differences.

METHOD

All children 4-6 years of age who came for assessment or were currently in treatment at a pervasive developmental disorder service of one of several centers in a large geographic region were identified. Children who received a diagnosis of autism (N=46) or Asperger's syndrome (N=20) on the basis of a diagnostic interview and had an IQ in the nonretarded range were given a battery of cognitive, language, and behavioral tests. Families were contacted roughly 2 years after the date of their enrollment in the study, and many of the tests were readministered.

RESULTS

Children with Asperger's syndrome had better social skills and fewer autistic symptoms 2 years after study enrollment than the children with autism. The differences in outcome could not be explained by initial differences in IQ and language abilities. Children with autism who had developed verbal fluency at follow-up were very similar to the children with Asperger's syndrome at study enrollment.

CONCLUSIONS

Although the exact mechanism for the differences in outcome remain to be determined, it appears that Asperger's disorder and autism represent parallel but potentially overlapping developmental trajectories.

Prolongation of brainstem auditory-evoked responses in autistic probands and their unaffected relatives

BACKGROUND

Brain function, as indexed by brain electrical activity, is heritable in humans, and it may be impaired in autism. Autism also has strong genetic determinants, and like all major psychiatric disorders, its complex clinical phenotype renders genetic studies difficult. Innovative strategies focused on alternative biological phenotypes are needed.

METHODS

The early brain auditory-evoked response was assessed in 73 autistic probands and 251 relatives who were compared with 521 normal controls.

RESULTS

We first confirmed in the autistic probands the presence of a slowing in nerve conduction in the auditory system as expressed by the prolongation of early brain auditory-evoked response under the form of I-III interpeak latencies (IPLs). Furthermore, we observed the same I-III IPL prolongation in the unaffected first degree relatives of the autistic probands compared with controls. Despite clear evidence of a coaggregation of autism and I-III IPL prolongation in families, the IPLs did not seem to be the sole liability factor for autism as suggested by the observation of 52% of families in which the autistic proband and relatives showed normal IPLs.

CONCLUSION

A prolongation of the early brain auditory-evoked response IPLs may be a marker for one of several deficits underlying autism and deserves further analysis as a potential alternative phenotype for the disorder.

The classification of autism, Asperger's syndrome, and pervasive developmental disorder

The current classification of the pervasive developmental disorders (PDDs) as conceptualized in both the DSM-IV and ICD-10 is deeply unsatisfying to many parents, front-line clinicians, and academic researchers. Is the diagnostic validity of the various disorders simply lacking empirical data for full substantiation, or does the overall conceptualization of the category have more fundamental problems, not reflecting the "true" nature of the phenomena? This paper argues the latter hypothesis. I review the historical development of the classification of PDD, summarize recent empirical data on issues of reliability and validity, and suggest a new approach to classification and understanding.

The familial aggregation of the lesser variant in biological and nonbiological relatives of PDD probands: a family history study

OBJECTIVE

To determine the risk of the lesser variant (or PDD-like traits) in the biological and nonbiological second- and third-degree relatives of PDD probands using a screening questionnaire and to investigate the extent to which the risk of the lesser variant differs according to various characteristics of the proband.

METHOD

The sample consists of a series of 34 nuclear families with 2 affected PDD children (multiplex, MPX), 44 families with a single PDD child (simplex, SPX), and 14 families who adopted a PDD child. Data on characteristics of the lesser variant in 1362 biological and 337 nonbiological second- and third-degree relatives were collected from parents by telephone interview and from several maternal and paternal relatives by questionnaire.

RESULTS

All components of the lesser variant were more common in biological relatives (BR) than nonbiological relatives (NBR), confirming the familial aggregation of the traits. Proband characteristics associated with an increased risk of the lesser variant in relatives were a higher level of functioning and coming from a MPX family.

CONCLUSIONS

These findings on the familial aggregation of the lesser variant suggest that the genes for PDD also confer susceptibility to the lesser variant and that PDD may be a genetically heterogeneous disorder.

Effects of misclassification on estimates of relative risk in family history studies

Two types of misclassification that commonly occur in family-genetic studies are distinguished: 1) nondifferential misclassification, in which the probability of error as to phenotype (presence or absence of psychiatric disorder) does not depend on exposure status (being kin to a case or control proband) and 2) differential misclassification, in which it does. Nondifferential misclassification of phenotype reduces the observed relative risk towards the null value, sometimes quite dramatically. Differential misclassification can bias the observed relative risk in either direction, depending on the different values of sensitivity and specificity among relatives of cases and controls. The impact of these biases on genetic-epidemiologic studies is reviewed and discussed. In particular, the ability to detect major gene effects from the pattern of relative risks in first-, second-, and third-degree relatives can be severely compromised. Although there are some methods available to correct the effects of nondifferential misclassification, a major priority for family history studies is to minimize differential misclassification.

High functioning autism and Childhood Disintegrative Disorder in half brothers

Childhood Disintegrative Disorder (CDD) is grouped with autism as a subtype of Pervasive Developmental Disorder (PDD) in ICD-10 and DSM-IV. This is the first report of autism and CDD cosegregating within a sibship. J. P. and M. P. are half-brothers with the same mother. J. P. is an 18-year-old with impairments in communication, social reciprocity, and stereotypies and was diagnosed with autism. M. P. is a 7-year-old who developed normally to 2 years 4 months. He then underwent a profound regression, becoming nonverbal and socially withdrawn, and lost adaptive skills. Investigations did not reveal any neurodegenerative process. M. P. was diagnosed with CDD. The rarity of the two conditions suggests a shared transmissible mechanism. The implications for autism/PDD genetic studies are discussed.

Ring chromosome 22 and autism: report and review

Ring chromosome 22 has been described in over 50 cases. A characteristic phenotype has not been fully delineated; however, long face, thick eyebrows, 2-3 toe syndactyly, mental retardation, adequate somatic growth and the absence of major malformations are noted in many cases. An 11-year-old boy with ring chromosome 22 and 46,XY,r(22)(p11.31-q13.31 approximately q13.33) karyotype presented with global developmental delay, autistic disorder, and dolichocephaly, apparently low-set and large ears, midface hypoplasia, and 2-3 toe syndactyly. This is the second report of a ring chromosome 22 with autistic disorder. There appears to be an association between abnormalities of chromosome 22, including r(22), and autistic disorder; however, this occurrence may be a result of the association of autistic disorder with mental retardation rather than specifically due to r(22). The physical findings in this case also suggest that ring chromosome 22 causes a subtle but distinct phenotype which has previously been proposed.

Evidence of linkage in subtypes of alcoholism

We believed that subtyping alcoholism might be an efficient strategy for mapping susceptibility genes. Cluster analysis is one of the possible statistical techniques for such a purpose. We required that, ideally, the variables to be used in cluster analysis should be: 1) related to alcoholism, 2) related to the severity of alcoholism, and 3) familial, i.e., correlated within families. Only three variables met all three conditions. Those included age of onset of ALDX1, smoking, and TPQ-HA. A global score of symptoms of alcoholism was systematically introduced as one of the variables composing a subset for cluster analysis, although this score did not show any familial aggregation. Our strategy led to a strong evidence of linkage at D15S230 in only 20 families whose members are mainly characterized by heavy smoking.

Imaging of autism: lessons from the past to guide studies in the future

OBJECTIVE

To review the scientific literature on the imaging of autism with a view to understanding how imaging can contribute to future studies.

METHODS

Medline was searched, and bibliographies from retrieved articles were reviewed. Inclusion criteria were a diagnosis of autism according to Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria, third edition or later, and a control group without autism.

RESULTS

The field suffers from a lack of replication studies and poor methodology in terms of not controlling for confounding variables. Enlarged brain size, particularly in the temporoparietal brain region, and decreased size of the posterior corpus callosum are the only findings that have been independently replicated.

CONCLUSION

Future imaging studies should attempt to investigate more homogeneous subgroups of patients such as those with "the lesser variant of PDD" and high-functioning patients with PDD who do not have comorbid medical conditions. A different approach, examining the individual behaviours that constitute the PDD spectrum and exploring these separately along with other associated variables such as neuropsychological deficits, structural and functional brain abnormalities, and genetic information could help identify biological mechanisms that do not follow diagnostic boundaries.

Age-of-onset classification of conduct disorder: reliability and validity in a prospective cohort study

OBJECTIVE

To test in a prospective clinical cohort study the reliability and validity of the age-of-onset subtyping of conduct disorder.

METHOD

Participants were adolescents referred to psychiatric clinics who met DSM-III-R criteria for conduct disorder by structured diagnostic interview. Age of onset was the reported age of the first conduct disorder symptom. The reliability of age-of-onset report was tested by assessing agreement within informant on interviews 2 to 4 weeks apart. Age-of-onset groups were compared within informant on rates of correlates and symptom and social functioning outcomes over a period of 3 years.

RESULTS

The reliability of age-of-onset report was low (kappa of 0.1 and 0.4 by adolescent and parent informant, respectively). Although the early-onset group had elevated rates of attention-deficit/hyperactivity disorder, family disadvantage, and aggressive and nonaggressive antisocial behaviors at inclusion, growth curve analysis showed that age-of-onset subtyping had no predictive validity.

CONCLUSIONS

The reliability of ascertainment of age of onset of antisocial behavior requires further study. While age-of-onset subtyping has heuristic value with respect to the study of the causal pathways to conduct disorder, it is premature to use this system in clinic settings.

Familial factors influence level of functioning in pervasive developmental disorder

OBJECTIVE

To determine whether siblings with pervasive developmental disorders (PDD) tend to have the same type and number of PDD symptoms or a similar level of functioning.

METHOD

The familial correlations for PDD subtype, symptom totals, adaptive behaviors, and nonverbal IQ were calculated for 94 children with PDD from 46 families.

RESULTS

On variables measuring PDD symptoms, only impairments in nonverbal communication and verbal/nonverbal status tended to run true within families. There was no familial aggregation of PDD subtype. In contrast, measures of nonverbal IQ and adaptive behaviors in socialization and communication showed a moderate degree of familial resemblance. The degree of familial resemblance did not change if the analysis was restricted only to those families in which both affected children met criteria for autism.

CONCLUSION

Insofar as the familial resemblance seen in PDD is due to genetic factors, these data provide some evidence that higher- and lower-functioning PDD children may arise from separate genetic mechanisms. Current gene-mapping studies of PDD may need to take this evidence of genetic heterogeneity into account.

Highly somatizing young adolescents and the risk of depression

OBJECTIVE

To determine if high levels of somatization symptoms in 13- to 16-year-olds from the general population predict risk of major depression and other psychiatric disorders 4 years later.

METHOD

Cohort study, using interview and self-report survey data from the 1983 Ontario Child Health Study (OCHS) and 1987 OCHS Follow-up. The study population included 1015 13- to 16-year-olds from the general community within Ontario. Baseline levels of somatization and emotional disorder were measured by the Survey Diagnostic Instrument, a checklist based on DSM-III criteria. Data were also collected for a range of sociodemographic factors, as well as the presence of chronic health problems. Major depression, anxiety disorders, and substance abuse and dependency at follow-up were measured using a self-administered questionnaire derived from the Diagnostic Interview Schedule. Bivariate and multiple logistic regression techniques were used to assess the relationship between high levels of somatization symptoms (>90th percentile) and later emotional morbidity, with adjustment for potential confounding factors, including gender and baseline disorders.

RESULTS

Highly somatizing adolescents are at increased risk of major depression 4 years later, an association that is not explained by detectable emotional disorder at baseline or gender differences between groups. There is an important interaction between somatization and emotional disorder in predicting risk of major depression. It is primarily the group of 13- to 16-year-olds not recognized as being emotionally disordered at the initial OCHS survey in which somatization symptoms increased risk of later depression. The young teen with high levels of somatic complaints had as much risk of later depression as his/her peer with more typical symptoms of emotional disorder. Highly somatizing adolescents were also more likely to describe panic attacks at 4-year follow-up. There was no increased risk of substance abuse/dependency in the highly somatizing group or in generalized anxiety.

CONCLUSIONS

High levels of somatic symptoms identified in young adolescents in the community represent a significant risk factor for major depression 4 years later, particularly in those individuals who do not present with more typical symptoms of emotional disorder. To detect the emergence of this serious emotional morbidity, adequate follow-up and continuity of care for these challenging patients are needed.

Heterogeneity and the genetics of autism

The objective of this review is to summarize recent data on the genetics of autism, highlight the evidence for genetic heterogeneity and extend the implications of these findings for the identification of susceptibility genes in this disorder. Family studies have shown that autism runs in families and twin studies indicate that the basis of that familial aggregation is genetic. As a result the prospects for the identification of susceptibility genes using either linkage or association studies are quite good. However, recent evidence is accumulating suggesting that the disorder is genetically heterogeneous; higher functioning individuals with autism may arise from separate genetic mechanisms that lower functioning ones. If true, this will make the detection of linkage and association much more difficult.

Influence of parental concordance for psychiatric disorders on psychopathology in offspring

OBJECTIVE

To examine the influence of parental mating types for substance abuse and anxiety/affective disorders on the risk of psychopathology among child and adolescent offspring.

METHOD

Emotional and behavioral disorders were assessed in offspring, aged 7 to 17 years, of male and female parents who served as probands from a family study of comorbidity of substance abuse and anxiety disorders.

RESULTS

The findings indicated that (1) patterns of psychopathology among offspring were similar for mothers and fathers; (2) spouse concordance for psychopathology was greater among parents with substance abuse than among those with anxiety, particularly among female substance abusers; (3) there was a direct relationship between the number of affected parents and the magnitude of psychopathology in children, particularly with respect to the anxiety disorders; and (4) by contrast, rates of conduct disorder were elevated only among offspring of dually affected parents, irrespective of the specific parental disorders.

CONCLUSIONS

These findings underscore the importance of the contribution of both mothers and fathers, particularly those with concordance for psychiatric disorders, to the development of psychopathology in offspring.

Genetics of autism: overview and new directions

Genetic epidemiology is the study of inherited factors involved in the etiology of a disease or disorder and uses the methods of both medical genetics and clinical epidemiology. In general, genetic epidemiology tries to answer the following four questions: Is the disorder inherited; What phenotype is inherited; How is it inherited or what is the mode of transmission; and What is the nature of the genetic mutation, if any, that gives rise to the disorder? The hope is that by identifying the gene or genes involved in pathophysiology, a much better understanding of the steps from gene product to phenotype will be possible, leading to improvements in diagnosis, an opportunity for thoughtful family planning, and perhaps, most important, to the development of treatments based on an understanding of the biochemistry of the disorder. We review the current knowledge of the genetic epidemiology of autism and the other pervasive developmental disorders (PDDs) and highlight promising new directions. There seems to be widespread agreement that the PDDs are caused, at least in part, by genetic factors. There is also some agreement on the phenotypic boundaries associated with these same genetic factors. However, many points of uncertainty remain, and several methodologic issues need to be resolved before further progress in mapping susceptibility genes is possible. We do not specifically review molecular studies, medical conditions associated with autism, or the broader autism phenotype, as these topics are covered in other papers in this special issue.

Psychopathology among offspring of parents with substance abuse and/or anxiety disorders: a high-risk study

This paper reports the results of a high-risk study of children under age 18 of parents who served as probands in a family study of comorbidity of substance abuse and anxiety disorders. There was a strong degree of specificity of familial aggregation of both the anxiety disorders and substance disorders. Rates of conduct disorder and depression were elevated among offspring of all affected parents. Inclusion of co-parent disorders in the evaluation of familial transmission in the present study strengthened the findings regarding the specificity of transmission of the anxiety disorders and the links between both parental substance abuse and antisocial personality with child conduct disorder.

Reliability and accuracy of differentiating pervasive developmental disorder subtypes

OBJECTIVE

To evaluate the ability of the DSM-IV criteria for the pervasive developmental disorders (PDD) to reliably and accurately differentiate PDD subtypes.

METHOD

The sample consisted of 143 children with various types of developmental disabilities. A diagnosis of PDD and PDD subtype was made by one clinician using information obtained from the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule. The raw data from the Autism Diagnostic Interview-Revised, clinical notes (excluding diagnostic opinion), Autism Diagnostic Observation Schedule, IQ, and other available data were independently assessed by three experienced raters, each of whom then made a separate, blind diagnosis. If there was any disagreement, a consensus best-estimate (CBE) diagnosis was made after discussion. To assess reliability, the agreement between the three raters was calculated using k. Accuracy was assessed by calculating the agreement between the clinician's diagnosis and the CBE and by calculating the error rates associated with the three raters using latent class analysis.

RESULTS

The current DSM-IV criteria show good to excellent reliability for the diagnosis of PDD, Asperger's disorder (AsD), and autism, but they show poor reliability for the diagnosis of atypical autism. The clinician (compared to the CBE) had little difficulty differentiating PDD from non-PDD children and autism from AsD but had more difficulty identifying children with atypical autism. The latent class analysis also showed that the average error rates of the three raters for a differentiation of atypical autism from autism were unacceptably high.

CONCLUSIONS

Although the psychometric properties of the current DSM-IV criteria for autism and AsD appear quite acceptable, there is likely to be a high rate of misclassification of children given a diagnosis of atypical autism.

Clinical and methodological factors related to reliability of the best-estimate diagnostic procedure

OBJECTIVE

The reliability and accuracy of the best-estimate diagnostic procedure were examined, and factors associated with reliability were determined.

METHOD

The subjects were 134 members of large multigenerational pedigrees densely affected by bipolar disorders or schizophrenia. Three best-estimate diagnoses were derived: first, by a research psychiatrist and research assistant unblind to the relatives' diagnoses; second, by two blind independent psychiatrists; third, by a panel of four blind psychiatrists. The subjects were characterized on several clinical and methodological variables, which were used to compare the agreements of two types of best-estimate diagnoses with the disagreements.

RESULTS

There was satisfactory agreement between the unblind and blind consensus best-estimate diagnoses and between the two blind independent psychiatrists. Latent class analyses revealed that limited sensitivity was the main source of imperfect reliability. Confusability analyses revealed that the most problematic diagnostic distinctions involved schizoaffective disorder, which was confused with schizophrenia, bipolar I disorder, and schizophreniform disorder. Blindness significantly affected diagnostic outcome in latent class analyses. Moreover, for diagnostic disagreements, unblind diagnoses had greater continuity with the most predominant diagnosis in the pedigree than did blind diagnoses. Diagnostic disagreements were associated with the presence of mixed affective and psychotic symptoms, less diagnostic certainty, and shorter duration of illness.

CONCLUSIONS

These results suggest that it is possible to identify cases that are more likely to lead to diagnostic disagreements in family and epidemiological studies and that blind diagnoses may help to prevent false positive diagnoses, which may be particularly detrimental to genetic linkage analyses.

Adequacy of interviews vs checklists for classifying childhood psychiatric disorder based on parent reports

BACKGROUND

The advantages and disadvantages of lay-administered structured interviews and self-administered problem checklists for estimating prevalence and associated features of childhood psychiatric disorder have attracted little comment. This article compares the scientific adequacy of these 2 instruments for classifying DSM-III-R categories of childhood psychiatric disorder in general population samples.

METHODS

Study data are from parental assessments of 251 children aged 6 to 16 years participating in a 2-stage measurement evaluation study. Reliability and validity were compared between the Diagnostic Interview for Children and Adolescents (the structured interview in the study) and the revised Ontario Child Health Study scales (the self-administered problem checklist used in the study).

RESULTS

Reliability estimates based on the kappa statistic were comparable for the 2 instruments and ranged from 0.21 (conduct disorder) to 0.70 (depression) on the lay interview and from 0.17 (depression) to 0.61 (oppositional defiant disorder) on the self-administered checklist. Validity coefficients tended to favor the checklist categories, but only marginally.

CONCLUSIONS

On balance, differences in reliability and validity were small between the 2 instruments. These differences would appear to have no discernible impact on the knowledge about prevalence and associated features of disorder generated by use of such instruments in general population surveys.

The effect of selection criteria on outcome studies of children with pervasive developmental disorders (PDD)

The objective of this paper is to see whether regression to the mean biases the differences on outcome observed between children with Asperger syndrome and autism. Children with pervasive developmental disorders (PDD) and normal nonverbal IQ were divided into those with Asperger syndrome and autism. It was hypothesized that IQ in the autistic children would fall at the 2-year outcome assessments since the autistic group represented a subgroup selected on the basis of extreme scores on a single measure. In fact, the Asperger syndrome group experienced a significant drop in nonverbal IQ contrary to expectation. Serial measurements of nonverbal IQ at inception indicated that this drop was probably a function of high initial nonverbal IQ scores that fall over time due to increasing complexity of problem-solving tests. The results are discussed in relation to outcome studies of high functioning children with PDD.

A high-risk pilot study of the children of adults with social phobia

OBJECTIVE

Children of patients with social phobia were studied to estimate their rates of psychiatric disorder.

METHOD

Twenty-six social-phobic outpatients who had at least one child between the ages of 4 and 18 years participated in the study. Information was collected from parents on all 47 children and from the children between 12 and 18 years of age. Diagnoses in the children were made based on DSM-III-R and were done by a best-estimate method, using parent and child reports from a modified Anxiety Disorders Interview Schedule for Children, the Survey Diagnostic Instrument, the Current Self-Report Childhood Inhibition Scale, and the Alcohol Dependence Survey.

RESULTS

Of the 47 children, 49% had at least one lifetime anxiety disorder diagnosis. The most common diagnoses were overanxious disorder (30%), social phobia (23%), and separation anxiety disorder (19%). Sixty-five percent had more than one anxiety disorder diagnosis. Lifetime major depression was found, in 8.5% of the children. Parents whose children met criteria for an anxiety disorder had a greater mean number of comorbid diagnoses than did the parents of unaffected children.

CONCLUSION

This pilot study suggests that children of social-phobic parents may have increased rates of psychiatric disorder. Further studies incorporating a control group are needed.

Risk and protective factors affecting the adjustment of siblings of children with chronic disabilities

OBJECTIVE

To examine the adjustment of nondisabled siblings of handicapped children.

METHOD

In a 3-year longitudinal study, 46 siblings of children with pervasive developmental disorder (PDD), 45 siblings of children with Down syndrome, and 46 siblings of developmentally normal children (serving as controls) were examined at time 1 using the sibling, primary caretaker, and teacher as informants. Both direct and indirect variables related to sibling adjustment were considered.

RESULTS

Significantly more difficulties were found in the siblings of children with PDD compared with the other two groups. Different correlates of adjustment were present in the siblings of the disabled compared with nondisabled children, and mediating factors differed in parent and teacher reports of internalizing difficulties in siblings of children with PDD. Marital satisfaction, lack of parental depression, a cohesive family, and a warm, nonconflictual sibling relationship were protective for normal control and Down syndrome siblings but not for PDD siblings.

CONCLUSION

Findings underline the risks for the siblings of children with PDD and suggest the importance of a transactional mechanism rather than identification of single risk or protective factors in predicting sibling adjustment. Subsequent data analysis in this longitudinal study will assist in defining these mechanisms and allow for improved intervention strategies.

Identifying thresholds for classifying childhood psychiatric disorder: issues and prospects

OBJECTIVE

To evaluate empirically the implications of choosing different thresholds to classify conduct disorder and attention-deficit hyperactivity disorder for estimating prevalence, test-retest reliability of measurement, and informant (parent/teacher) agreement and for evaluating comorbidity and associated features of disorder.

METHOD

Data for the study came from problem checklist assessments done by parents and teachers of children aged 6 to 16 years (N = 1,229) selected with known probability from a general population sample and from structured interviews obtained in a stratified, random subsample (n = 251).

RESULTS

Estimates varied widely depending on the rationale used to set thresholds. Percent prevalence went from 0.1 to 39.2; kappa estimates of test-retest reliability went from .19 to .82. Parent-teacher agreement based on kappa went from .0 to .38. Relative odds between disorder and associated features varied twofold.

CONCLUSION

Use of different rationales to set thresholds for classifying childhood psychiatric disorder in the general population has profound implications for what we learn about the epidemiology of childhood disorder.