Debate and argument: there are connections between brain and mind and it is important that Rett syndrome be classified somewhere

Categorical Approaches to the Diagnosis of Autism

Although autism was first reported in 1943 nearly 40 years elapsed before the disorder was included as an official diagnosis in the American (DSM) classification system. In the last two decades guidelines for the diagnosis of this, and related, conditions have evolved based on a growing body of research. An important recent development has been the convergence of the American (DSM) and International (ICD) diagnostic systems. Although these two official systems differ somewhat in format and intended use, the advent of consistent approaches to the diagnosis of autism will facilitate both research and clinical service. Data that have informed the development of these systems are reviewed and areas of continuing controversy are noted.

Autism in DSM-5: progress and challenges

BACKGROUND

Since Kanner's first description of autism there have been a number of changes in approaches to diagnosis with certain key continuities . Since the Fourth edition of the Diagnostic and Statistical Manual (DSM-IV) appeared in 1994 there has been an explosion in research publications. The advent of changes in DSM-5 presents some important moves forward as well as some potential challenges.

METHODS

The various relevant studies are summarized.

RESULTS

If research diagnostic instruments are available, many (but not all) cases with a DSM-IV diagnosis of autism continue to have this diagnosis. The overall efficiency of this system falls if only one source of information is available and, particularly, if the criteria are used outside the research context. The impact is probably greatest among the most cognitively able cases and those with less classic autism presentations.

CONCLUSIONS

Significant discontinuities in diagnostic practice raise significant problems for both research and clinical services. For DSM-5, the impact of these changes remains unclear.

Classification of autism and related conditions: progress, challenges, and opportunities

Since Kanner's classic description of the syndrome of early infantile autism in 1943, conceptions of the disorder have evolved while retaining important continuity with what Kanner viewed as the hallmarks of the condition—social impairment (autism) and difficulties in dealing with change in the nonsocial world (insistence on sameness). This paper reviews the history of this evolution and the important potential advantages and disadvantages of changes being contemplated for DSM-5. The convergence of diagnostic approach in DSM-IV and ICD-10 provided a shared system that fostered a tremendous body of research. The changes proposed in DSM-5 may impact both research comparability and service eligibility.

Recognizing and treating Rett syndrome in schools

A review of the literature on Rett syndrome (RS) for school-based professionals is presented from a behavioral perspective. A description of RS is provided, including distinctive physical, behavioral, and emotional features, diagnostic criteria for classic and formes frustes forms of RS, and stages of the disorder. The similarities and differences between RS and autism are reviewed. Controversies regarding the classification of RS are presented, including whether RS should be classified as a neurological or psychiatric condition and whether RS should remain classified as a pervasive developmental disorder. Last, a variety of options for the treatment of RS are discussed.

Autistic disorder symptoms in Rett syndrome

According to the major classification systems it is not possible to diagnose a comorbid autistic disorder in persons with Rett syndrome. However, this is a controversial issue, and given the level of functioning of persons with Rett syndrome, the autistic disorder is expected to be present in a comparable proportion as in people with the same level of functioning. To investigate, parents of 52 females with classical and atypical Rett syndrome (2.4-49.3 years) completed the Developmental Behavior Checklist (DBC), the Diagnostic Interview for Social and Communication Disorders (DISCO) and the Dutch Vineland Screener 0-6 (VS 0-6). All participants had a severe to profound intellectual disability (ID) according to the VS 0-6. Behavior indicated an autistic disorder in 42 (DBC) to 58 percent (DISCO) of the Rett cases. Autistic behavior had decreased in 19 percent such that they no longer met the criteria for autistic disorder. Some participants were suspected of having a comorbid autistic disorder, though not more often than can be expected at their level of functioning. Clinicians should be aware of the possibility of a comorbid autistic disorder as much as they should be in other people with this level of functioning.

Autism and autism spectrum disorders: diagnostic issues for the coming decade

A decade and a half have elapsed since DSM-IV and ICD-10 appeared. During this time the convergent definitions of autism and related disorders in these two diagnostic systems have stimulated tremendous research. In this brief review we summarize areas of progress and continuing controversy, including approaches to diagnosis in more cognitively able individuals on the autism spectrum, diagnosis in very young infants, the issue of subtypes, and the potential contribution of genetic research. The use of dimensional assessments has some advantages as do the insights from prospective studies. At this point it will be important to study not only causative factors but developmental processes disrupted in these disorders.

Features of autism in Rett syndrome and severe mental retardation

It has long been recognized that there is phenotypic overlap between Rett syndrome (RS) and autism. Advances in our clinical and genetic understanding of RS over the past decade have made clear that the cause and course of RS and autism are distinct (except perhaps in a few cases). Despite this, further delineation of the phenotypic overlap between RS and autism is warranted to enhance clinical decision-making and to further understanding of neuropathological development in both disorders. The present study measured autistic symptoms using the Autism Behavior Checklist (ABC) in a sample of girls with RS and a comparison group of girls with severe and profound mental retardation (SMR). Controlling for developmental level and motor ability, girls with RS scored more highly than those with SMR on the Sensory and Relating subscales. In contrast, there were no group differences on the Body and Object use, Language and Social and Self-help subscales. Further work on the characterisation of the behavioral phenotype of genetic disorders such as RS and autism may aid in identifying the neuropathogenic processes that lead from gene-to-brain-to-behavior.

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.