Lack of expansion of triplet repeats in the FMR1, FRAXE, and FRAXF loci in male multiplex families with autism and pervasive developmental disorders

Sib, twin, and family studies have shown that a genetic cause exists in many cases of autism, with a portion of cases associated with a fragile X chromosome. Three folate-sensitive fragile sites in the Xq27-->Xq28 region have been cloned and found to have polymorphic trinucleotide repeats at the respective sites; these repeats are amplified and methylated in individuals who are positive for the different fragile sites. We have tested affected boys and their mothers from 19 families with two autistic/PDD boys for amplification and/or instability of the triplet repeats at these loci and concordance of inheritance of alleles by affected brothers. In all cases, the triplet repeat numbers were within the normal range, with no individuals having expanded or premutation-size alleles. For each locus, there was no evidence for an increased frequency of concordance, indicating that mutations within these genes are unlikely to be responsible for the autistic/PDD phenotypes in the affected boys. Thus, we think it is important to retest those autistic individuals who were cytogenetically positive for a fragile X chromosome, particularly cases where there is no family history of the fragile X syndrome, using the more accurate DNA-based testing procedures.

Integrating assessment data from multiple informants

OBJECTIVE

To examine the consequences for measurement of child psychiatric disorder (conduct and oppositional disorders) of not integrating the data on the same individual from different informants compared with integrating the information from parents and teachers, using three different strategies.

METHOD

Data for the study came from problem checklist assessments done by parents and teachers of children aged 6 to 16 years (N = 1,134) selected with known probability from a general population sample and from structured interviews obtained in a stratified random subsample (n = 251).

RESULTS

As expected, parent-teacher agreement was low. The pattern of associated features of disorder was found to vary markedly in parent-identified compared with teacher-identified disorder. Furthermore, combining informants had the disadvantage of masking the distinctive patterns of associated features noted in informant-specific disorders. Finally, by treating disorder as informant-specific, the internal properties of the measure are not generally inferior to those obtained by combining informants in various ways.

CONCLUSION

Child psychiatric disorders should be conceptualized as informant-specific phenomena.

High phenotypic correlations among siblings with autism and pervasive developmental disorders

The objective of this study was to examine familial factors influencing clinical variation in sibships that contained at least 2 children affected with autism or another form of pervasive developmental disorder (PDD). The sample included a total of 60 families, 23 with multiple cases of PDD and 37 with a single affected child. Measurements of IQ, adaptive behaviors in socialization and communication, and autistic symptoms were taken on all affected children. A high intraclass correlation, especially on IQ and an index of social behaviors, was observed between affected children from the same family. In contrast, low correlations were observed on measurements of IQ and adaptive behavior between affected and unaffected children from the same family. These data indicate that variation in severity of PDD is influenced by familial, and probably genetic, mechanisms. The results are discussed in relation to current theories on the genetics of autism and the heritable mechanisms underlying variations in clinical severity.

Somatization and the vocabulary of everyday bodily experiences and concerns: a community study of adolescents

OBJECTIVE

To describe the frequency of everyday bodily experiences and health concerns in a general population of adolescents 12 to 16 years of age in Ontario and to explore whether the concept of "somatization," identified from those youths with many of these symptoms, is meaningful and related to other variables.

METHOD

A representative sample of the population was obtained by stratified random sampling. Children with a chronic medical condition were excluded. Parents and their adolescent children filled out a series of questionnaires to measure health concerns, complaints, and more dramatic losses of function. Information was also collected on certain background factors, psychiatric problems, and impairments in adaptive functioning.

RESULTS

Parents and youths endorsed the items with the same rank order of frequency, but there was virtually no agreement between parents and youths on the presence or absence of individual somatic symptoms. Users of medical services did not tend to have many more health concerns than others, and there was a weak relationship between the number of health concerns reported by a youth and both impairment in adaptive functioning and psychiatric problems.

CONCLUSION

These data suggest that the concept of somatization has limited general value over and above a relationship with other psychiatric problems.

Predicting the one-year course of adolescent major depression

OBJECTIVE

To identify specific clinical and social functioning variables that predict persistence of major depression over a 1-year period of follow-up.

METHOD

The sample consisted of 67 adolescents with major depression, drawn from consecutive referrals to psychiatric clinics in a defined, geographic catchment area. Clinical interviews and questionnaires measuring behaviors, symptoms, and social functioning were administered to both the adolescent and a parent at inception and at follow-up. Discriminant function analyses were used to identify inception variables that predicted clinical course independent of severity of depressive symptoms and global functioning.

RESULTS

At 1-year follow-up, major depression remitted in 66% of subjects. Persisters were characterized at inception as older, more likely to have substance use or anxiety disorders, less involved with fathers, and less responsive to mother's discipline compared with remitters. The effect of these prognostic factors was independent of symptom severity and global functioning.

CONCLUSION

These variables appear to reflect perpetuating and ameliorating factors influencing the short-term course of major depression. The findings suggest that treatments for adolescent depression that aim to enhance parent-adolescent relationships, and that specifically target coexisting disorders, should be evaluated for effectiveness.

Asperger's syndrome and autism: differences in behavior, cognition, and adaptive functioning

OBJECTIVE

To determine whether subtypes of children with pervasive developmental disorder (PDD) differed on variables that were relatively independent of distinguishing criteria.

METHOD

Higher-functioning children with PDD, 4 through 6 years of age, were differentiated into those with autism (n = 47) and those with Asperger's syndrome (n = 21) on the basis of delayed and deviant language development. The groups were then compared on a wide range of measures including PDD symptoms, adaptive behaviors in communication, socialization, and activities of daily living, and an assessment of verbal and nonverbal cognitive skills.

RESULTS

Significant differences between the groups existed on many PDD symptoms, adaptive behaviors, and cognitive measures of language competence, but not on aspects of nonverbal communication, nonverbal cognition, or motor development.

CONCLUSION

Subtypes of children with PDD can be identified that differ on variables relatively independent of defining characteristics. These findings should provide a firm foundation into research to determine whether children with autism and Asperger's syndrome also differ on outcome, etiology, and response to treatment.

Parents and collateral relatives of children with pervasive developmental disorders: a family history study

The objective of this study was to see whether, using the family history method, the risk for pervasive developmental disorder (PDD), cognitive impairments, and other psychiatric symptoms is greater in the parents and collateral relatives of probands with PDD compared to a control group. A semistructured family history interview was carried out with the parents of 52 probands with PDD and 33 parents of controls. Rates of cognitive impairments and psychiatric problems were not found more frequently in parents or relatives of PDD probands compared to relatives of controls, but four cases of PDD were reported among the extended families of the PDD probands. The relatives with PDD were related to the probands through the maternal line, possibly suggesting some form of maternal influence on inheritance or reduced penetrance in females with the PDD genotype.

Vineland Adaptive Behavior Scales as a summary of functional outcome of extremely low-birthweight children

This study reports moderate to high Pearson correlations between Vineland Adaptive Behavior Scale (VABS) subscale and total scores and a variety of cognitive, academic and motor performance tests on a population of extremely low-birthweight infants assessed at eight years of age. The subscales describe adaptive behaviour in daily living, communication, motor function and socialization, as well as an adaptive behaviour composite score. Because it can provide a norm-referenced description of functional outcomes and can be used to assess all children regardless of disability, the authors believe that the VABS should be applied uniformly by all groups reporting school-age outcome of neonatal intensive-care populations.

Evaluation of diagnostic criteria for autism using latent class models

OBJECTIVE

To illustrate the use of latent class models for comparing alternative diagnostic criteria for autism. The models are based on the notion that the "true" classification of an individual is unknown but does exist at some unobserved, or "latent," level. Estimates of sensitivity and specificity are obtained for each set of diagnostic criteria through maximum likelihood techniques in relation to the latent standard.

METHOD

In this paper, latent class models are used to compare DSM-III, DSM-III-R, and ICD-10 criteria for autism in a sample of 342 individuals with autism or other developmental disabilities. The diagnoses were made by one or more child psychiatrists who evaluated each patient and assigned a diagnosis of autism based on their own expert clinical judgment. In addition, the raters also determined whether criteria were met for the various diagnostic systems.

RESULTS

The results indicate that the ICD-10 criteria agree best with the latent standard and a diagnosis based on expert opinion.

CONCLUSION

It is suggested that latent class models can be usefully applied to the evaluation of other psychiatric disorders as well and represent an important new tool in evaluating diagnostic criteria by providing a way of dealing with data lacking an observable gold standard.

Seat-belt legislation and risk homeostasis: further analysis of the British data

It has been suggested that seat-belt legislation may result in drivers' feeling overprotected and their consequent riskier driving may lead to more injuries to other road users (the risk homeostasis or compensation theory). We have examined data in Britain before and after legislation made seat-belt use compulsory for front-seat occupants of specified vehicles. The relative numbers of injuries to cyclists and pedestrians in collisions with vehicles requiring and not requiring seat-belt use were compared, using a log-linear analysis taking into account possible confounding variables. It was not possible directly to incorporate vehicle distance travelled for the two categories of vehicle. However, a simple adjustment for differential vehicle use accounted for most of an apparent effect. The revised odds ratio (for mandated seat-belt use vehicles versus nonmandated, post- versus prelegislation) was 1.04 for cyclists and 1.06 for pedestrians, showing minimal, if any, evidence for the theory.

Parent and teacher agreement in the assessment of pervasive developmental disorders

Although it is well known that informants often disagree about the degree of psychopathology in children, this issue has not been systematically evaluated in children with autism. The objective of this paper is to estimate the extent of agreement between parents and teachers on the assessment of autistic symptoms and adaptive behavior skills. We assessed 83 children, 4-6 years of age, with a diagnosis of pervasive developmental disorder (PDD), using the Autism Behavior Checklist (ABC) and the Vineland Adaptive Behavior Scales (VABS). Parents and teachers rated each child on each measure. While there was good agreement between informants on the VABS, teachers tended to rate the PDD children higher than parents. In contrast, there was virtually no agreement on the ABC. High levels of stress experienced by parents appeared to be associated with parents reporting more autistic behaviors and less adaptive skills than teachers. As with other child psychiatric disorders, caution must be exercised in combining information from several informants.

Field trial for autistic disorder in DSM-IV

OBJECTIVE

This project focused on the development of the definition of autism for DSM-IV.

METHOD

Multiple sites were involved in obtaining information regarding 977 patients with the following clinician-assigned diagnoses: autism (N = 454), other pervasive developmental disorders (N = 240), and other disorders (N = 283). A standard coding system was used, and the raters (N = 125) had a range of experience in the diagnosis of autism. Patterns of agreement among existing diagnostic systems were examined, as was the rationale for inclusion of other disorders within the class of pervasive developmental disorders.

RESULTS

The DSM-III-R definition of autism was found to be overly broad. The proposed ICD-10 definition most closely approximated the clinicians' diagnoses. Inclusion of other disorders within pervasive developmental disorders appeared justified. Partly on the basis of these data, modifications in the ICD-10 definition were made; this and the DSM-IV definition are conceptually identical.

CONCLUSIONS

The resulting convergence of the DSM-IV and ICD-10 systems should facilitate both research and clinical service.

Cohesive discourse in pervasive developmental disorders

Investigated the use of cohesive links to create a reciprocal conversation in individuals with autism, Asperger syndrome, and a control group of children and adolescents with nonspecific social problems. All subjects engaged in a 10-minute conversation with an examiner that touched on various topics. The conversation was audiotaped, transcribed, and coded blindly for several types of cohesive links. Compared to controls, the higher functioning autistic group referred less to a previous stretch of the conversation and more to an aspect of the physical environment. The Asperger group, on the other hand, was very similar to the controls except they made more unclear references that were difficult to interpret. Implications of these findings for understanding the communicative failure of subjects with pervasive developmental disorder are discussed.

Sex differences in pervasive developmental disorders

Assessed differences in sex ratio, severity of associated mental retardation, and various metrics of severity of autism in autistic, PDD-NOS, and developmentally disordered (non-PDD) cases. Males with autism were more frequent than females, particular at higher IQ levels. The three clinical groups differed, in expected ways, in the various measures of severity of autism with the PDD-NOS cases being intermediate between the strictly diagnosed autistic group and the non-PDD developmental disordered group. Sex differences were primarily confined to IQ; sex differences in other metrics of severity of autism were not prominent. Implications for future research are discussed.

Evaluation of the Diagnostic Interview for Children and Adolescents for use in general population samples

This article presents evaluative data on the use of the Diagnostic Interview for Children and Adolescents-Revised (DICA-R) to classify DSM-III-R disorders in the general population. Data for the analyses came from a probability sample (N = 251) of parent-child/adolescent dyads aged 6 to 16 separately administered the DICA-R on two occasions, 10- to 20 days apart, by trained lay interviewers and child psychiatrists. Data are presented on prevalence, test-retest reliability, parent-child/adolescent agreement, and trained lay interviewer-child psychiatrist agreement. High prevalences of oppositional defiant disorder derived from parent assessments and overanxious disorder and dysthymia derived from adolescent assessments suggest that these disorders may be overidentified. Interview data provided by 6- to 11-year olds to classify the internalizing disorders were too unreliable to be useful. Agreement between parent-child/adolescent dyads was generally low while agreement between trained lay interviewers-child psychiatrists was generally high.

Lack of cognitive impairment in first-degree relatives of children with pervasive developmental disorders

OBJECTIVE

The objective of this study was to test the hypothesis that mild cognitive impairments aggregate in the unaffected first-degree relatives of probands with autism or pervasive developmental disorders (PDD).

METHOD

The unaffected siblings and parents of 52 PDD probands and 33 Down syndrome and low birth weight controls were administered a battery of psychometric tests. The tests included measures previously found to be depressed in siblings of autistic children as well as cognitive deficits seen in PDD subjects of normal IQ. In addition, the Vineland Adaptive Behavior Scales were administered to siblings to measure the social-communication impairments found in PDD.

RESULTS

Neither the siblings nor parents of the PDD probands demonstrated lower cognitive or adaptive behavior scores compared with controls. Developmental histories did not reveal greater rates of social, cognitive, or language delays, nor was there evidence to suggest that relatives of subgroups of PDD probands were different from each other.

CONCLUSION

These findings indicate that, apart from relatives with PDD, cognitive and social impairments do not aggregate in the families of PDD probands.

Familial aggregation of emotional and behavioral problems of childhood in the general population

OBJECTIVE

This study sought to evaluate the existence and implications of familial aggregation of emotional and behavioral problems of childhood in a general population sample.

METHOD

The children included in the study were chosen with the use of a sampling technique that identified households in which there were two or more children aged 4-16 years living at home at the time of the survey. Ratings on checklists of emotional and behavioral problems were obtained from parents, teachers of children in elementary school, and the children themselves if they were adolescents aged 12-16. Children were classified as having problems if their scores on scales of conduct, attention deficit, or emotional problems were in the top 10% of the distribution of scores from any informant.

RESULTS

There was evidence for familial aggregation of these problems, particularly conduct and emotional problems. However, this was largely derived from the parents' reports of symptoms, not the teachers' or adolescents' reports. The degree of familial aggregation varied according to certain sibship characteristics and patterns of comorbidity.

CONCLUSIONS

Familial aggregation of emotional and behavioral problems does exist in a community population and is not simply an artifact of clinic attendance.

Evaluation of the original Ontario Child Health Study scales

This article presents evaluative information on the use of the original Ontario Child Health Study scales to serve as original-level measures of conduct disorder, hyperactivity and emotional disorder among children in the general (non clinic) population. Problem checklist assessments were obtained from parents and teachers of children aged six to 16 and youth aged 12 to 16 drawn from a general population (n = 1,751); and a mental health clinic sample (n = 1,027) in the same industrialized, urban setting. The results showed that the original OCHS scales possess adequate psychometric properties to be used as original-level measures of disorder. Correlations between individual items and their hypothesized scales were very strong, indicating convergent validity, while correlations between the same items and other (non hypothesized) scales were lower, indicating discriminant validity. Item analyses indicated that individual scale items possess both convergent and discriminant validity. Although the scales were skewed to the positive end of the continuum, they demonstrated good internal consistency (all estimates > or = 0.74) and test-retest (all estimates > or = 0.65) reliability. Finally, three different validity analyses confirmed hypotheses about how the original OCHS scales should perform if they provide useful measures of disorder.

Predicting substance use in early adolescence based on parent and teacher assessments of childhood psychiatric disorder: results from the Ontario Child Health Study follow-up

This article examines relationships between psychiatric disorder, poor school performance, family dysfunction and low family income in a cohort of 8-12-year-olds and use of tobacco, marijuana and hard drugs 4 years later. Conduct disorder assessed by teachers predicted use of alcohol and hard drugs, while low family income and poor school performance predicted use of tobacco. Neither attention-deficit disorder nor emotional disorder was related to adolescent substance use. Although behavioural deviance in childhood is associated with adolescent substance use, it has limited potential for identifying groups at risk in the general population for purposes of preventing substance use in later years.

Evaluation of the revised Ontario Child Health Study scales

This article describes the development and evaluation of the revised Ontario Child Health Study (OCHS) scales to measure conduct disorder, oppositional disorder, attention-deficit hyperactivity disorder, overanxious disorder, separation anxiety and depression based on DSM-III-R symptom criteria. Problem checklist assessments were obtained from parents and teachers of children aged 6-16 and youths aged 12-16 drawn from: (1) a general population sample (N = 1751); and (2) a mental health clinic sample (N = 1027) in the same industrialized, urban setting. Evaluation of the revised OCHS scales indicates that they possess adequate psychometric properties and provide an efficient means to obtain measurements of childhood psychiatric disorder, in general population studies, that correspond to DSM-III-R classification of disorder.

The validity of autistic spectrum disorders: a literature review

The objective of this literature review is to assess the validity of autistic spectrum disorders (ASD). Twenty papers were identified that adequately investigated the internal or external validity of various subtypes of ASD. At least three groups can be distinguished from autism on clinical grounds; an Asperger syndrome subtype, and two atypical subtypes characterized by low IQ and high IQ. However, the evidence that these clinical distinctions carry inferences with respect to etiology, clinical course, and treatment is only suggestive. Nevertheless, the specification of several ASD subtypes might promote further research and resolve many of the nosologic issues with respect to the classification of pervasive developmental disorders (PDDs).

A review of the DSM-III-R criteria for autistic disorder

The objective of this paper is to review the psychometric properties of the new DSM-III-R criteria for autism. Five data sets were evaluated according to a set of methodological criteria. The results indicate that the DSM-III-R criteria for autistic disorder have, on average, very good sensitivity, but much lower specificity. The implications of this are (a) greater numbers of children diagnosed as autistic; (b) greater numbers of children misdiagnosed as autistic; and (c) greater heterogeneity among samples of autistic children. In essence, the DSM-III-R criteria act more like screening tests than diagnostic criteria. Conceptual and methodologic issues in the evaluation of diagnostic criteria are discussed.

Can learning disabilities in children who were extremely low birth weight be identified at school entry?

This prospective study was designed to test the hypothesis that a significant proportion of extremely low birth weight (ELBW) children identified as "at risk" for school problems at age 5 years by the Florida Kindergarten Screening Battery (FKSB) will present with specific learning disability (LD) when retested at age 8 years. A regional cohort of 81 of 84 ELBW survivors born between 1980 and 1982 were reassessed at age 8 years by Wechsler Intelligence Scale for Children-Revised (WISC-R), Wide Range Achievement Test-Revised (WRAT-R), and tests of motor function. The association of FKSB risk status and WRAT-R reading subtest for predicting general reading disability in the overall sample at age 8 years resulted in a sensitivity of 0.68, specificity of 0.48, and a likelihood ratio of 1.3. Of the 43 "normal" children at age 5 years with no neurosensory impairments and IQ > or = 84 (McCarthy GCI), 49% were considered to be at "mild" to "high" risk for future LD. The prevalence of specific LD (reading disorder) at age 8 years in children with normal IQ (WISC-R > or = 85) was 28%. The positive predictive value of the 5-year FKSB for identifying children with specific LD at age 8 years was 0.20 (sensitivity 0.33, specificity 0.48). We conclude the FKSB is not an efficient tool for predicting either general or specific LD in ELBW children.