Keywords
Although cases resembling autism were probably first reported more than 2 centuries ago, the credit for describing autism as a distinct disorder goes to Leo Kanner. In his seminal article, Autistic Disturbances of Affective Contact, he described, in unusual detail, 11 children without the ability to form social relationships. According to Kanner, these children showed characteristic features including aloofness, lack of imagination, and persistence of sameness; they came from “highly intelligent families” but had “very few really warm hearted fathers and mothers.” These families were “strongly preoccupied with abstractions of a scientific, literary or artistic nature and limited in genuine interest in people.” One year later, Vienna-born physician, Hans Asperger,
2
identified similar symptoms in 4 children who possessed similar characteristics to those studied by Kanner but lacked “language delays” and were “exceptionally gifted.”2
Subsequently, Lorna Wing3
gave the label of Asperger syndrome to these children. Around the same time, Rutter4
proposed 4 sets of diagnostic criteria for autism: social impairment, language disturbances, insistence on sameness, and onset before 30 months of age.DSM IV and ICD 10 criteria
Rutter’s
4
and Wing’s3
definition of autism was largely responsible for the introduction of autism as a distinct disorder in the DSM (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition)/ICD (International Classification of Diseases) systems of classification. At present, autism is conceptualized both in the DSM IV5
and the ICD6
as the main category in a group of disorders, the pervasive developmental or autism spectrum disorders (ASD), all of which are characterized by similar reciprocal social and communication deficits and rigid ritualistic interests beginning in early childhood. Other disorders in this category include Asperger syndrome, pervasive developmental disorder not otherwise specified (PDDNOS), Rett syndrome, and disintegrative disorder.Patients with Asperger syndrome, as currently defined in the DSM IV, suffer from autistic social dysfunction but without mental retardation or language delay. Rett syndrome, caused by mutations in the MECP2 gene, is characterized by autistic features in one of its phases, whereas patients with disintegrative disorder develop normally in the first 4 to 5 years of life and then go through a period of disintegration. The last category, PDDNOS, is reserved for patients who are within the autistic spectrum but do not meet the threshold for any of the named disorders. For practical purposes, the term ASD often refers to autism, Asperger syndrome, and PDD NOS, excluding Rett syndrome and disintegrative disorder. Thus, although the diagnosis of classic autism is straightforward, the identification of the subtle forms of ASD and the delineation of its various subtypes can be particularly challenging. Partly because of this difficulty in separating the subtypes of ASD, the upcoming edition of the DSM is likely to introduce a paradigm shift in its approach to the classification of autism.
Proposed DSM V criteria
The fifth edition of the DSM (DSM V), scheduled to be published in 2013, is likely to introduce a single category of ASD and eliminate the subcategories. In brief, the draft of the DSM V has published on its Web site
7
the following changes. First, the deficits of social interaction and communication that existed in DSM IV have now been merged into a single criterion of deficits in social communication and interaction. This is because, according to the draft criteria, deficits in communication and social behaviors are inseparable and more accurately considered as a single set of symptoms. The deficits must be clinically significant and persistent. These deficits should include marked impairment of both verbal and nonverbal communication used for social interaction; lack of social reciprocity (the degree of lack of reciprocity is not specified); and a failure to develop peer relationships at the appropriate developmental level. The second criterion consists of restricted repetitive interests shown by at least 2 of the following:- 1.Stereotyped motor or verbal behaviors, or unusual sensory behaviors (unusual sensory behaviors were not included in the DSM IV)
- 2.Excessive adherence to routines and ritualized patterns of behavior
- 3.Restricted, fixated interests.
The third criterion states that the symptoms of autism must be present in early childhood (in contrast with the DSM IV, which required the symptoms to be present before 3 years of age), with the caveat that the symptoms may not become fully apparent until social demands exceed the limited capacities.
Thus, from DSM III (when autism was first introduced in the classificatory system) to the proposed DSM V, the approach to the classification of ASD seems to have gone full circle, beginning with lumping to splitting and back to lumping again. The rationale for eliminating Rett disorder and disintegrative disorder is presumably that they are now conceptualized as being more neurologic than psychiatric. Regarding the proposed elimination of Asperger syndrome (or Asperger disorder), according to the DSM V task force,
7
the disorder is difficult to separate from autism with normal intelligence and has not been shown to be a valid category. However, a diagnosis does not have to be valid to be useful.8
Although there is no firm evidence that Asperger syndrome is distinct from autism, there is no denying that a diagnosis of Asperger syndrome can inform clinicians about the level of functioning, a pattern of behavior, and a likely outcome. Thus, the elimination of Asperger syndrome seems both unfortunate and premature.9
Diagnostic criteria and prevalence
One result of the changes in the diagnostic criteria has been the large increase reported in recent years in the prevalence of autism. When first described, autism was regarded as a rare condition affecting no more than 4 per 10,000; however, it is now much more common, occurring in at least 1 out of every 100 children. For example, a recent South Korean study reported that 2.6% of children aged 7 to 12 years meet the diagnostic criteria of ASD.
11
Autism is no longer regarded as a single entity but as a collection of disorders grouped together as ASD. The condition described by Kanner, though uncommon, was not difficult to recognize. Children with autism typically show stereoptypic behaviors, perhaps repeating words or sentences, preoccupied with routines and rituals, lost in a world of their own, often withdrawn and aloof. However, children with suspected ASD, although common, are also difficult to identify because they often present with a range of deficits ranging from the most severe to the almost invisible. The distinction between autism/autistic disorders and ASD/other psychiatric disorders often seems vague and ill defined.ASD in primary care
Because most children with ASD are first seen not by the specialist but by pediatricians and family practitioners, this article synthesizes the findings of recent studies dealing with the presentation and diagnosis of ASD in primary care and its distinction from other common psychiatric disorders of childhood. However, the ability of pediatricians to make this diagnosis depends not only on their training and background but also on the time they have at their disposal. Few pediatricians have enough time to screen for this condition. For example, in a mail survey of pediatricians, only about 8% endorsed screening for ASD. Although a significant number of the responders reported that they were not familiar with the screening procedures, others reported that they did not have enough time to conduct the assessments.
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Symptoms of autism
Core Symptoms of Autism
It is useful to categorize the symptoms of autism into 2 broad categories: core symptoms and secondary/comorbid symptoms. The core symptoms consist of reciprocal social deficits, communication impairment, and rigid ritualistic interests.
5
Recent studies suggest that the first 2 symptoms (social deficits and communication impairment) can be merged into a single category of social-communication impairment,7
reducing the triad of autistic symptoms to a dyad of social-communication impairment and rigid restricted interests. Although each of these symptoms can occur in a variety of psychiatric disorders( hence the importance of differential diagnosis) it is the clustering of these symptoms in the same individual that makes the disorder so unique and fascinating. However, some investigators think that the correlation between social-communication impairment and rigid ritualistic interests has been exaggerated, and that their underlying neurobiological mechanisms might be different. However, from a clinical standpoint, whenever a child presents with social difficulties and restricted compulsive interests, an in-depth autism-specific evaluation should be considered. In addition to the clustering of symptoms, the clinician should also take into consideration the age of presentation because different symptoms emerge at different periods during the life span.5
Thus, during early childhood, children with autism are likely to present with language deficits and problems with hyperactivity; however, during adolescence, the symptoms might change to problems with relationships and with regulation of mood. Apart from the pattern of symptoms and the age of presentation, another factor that should be considered is whether or not the child has intellectual disability or other psychiatric disorders, as discussed later.Secondary or Comorbid Features
Problems such as hyperactivity, aggression, and self-injurious behaviors occur in up to half of children with ASD.
11
, 12
More common in patients with intellectual disability, these symptoms significantly affect the quality of life of the affected individuals and their families. Depressive symptoms often emerge during adolescence.13
At times, depressive, psychotic symptoms and suicidal behavior can also occur.14
, 15
, 16
, 17
During late adolescence and early adulthood, affected persons might become increasingly slow in their body movements and may even develop catatonia, a potentially life-threatening condition that may occur in about 10% to 15% of patients with Asperger syndrome.18
Association with intellectual disability
Most patients with autism suffer from intellectual disability. Along with epilepsy, the relationship between autism and intellectual disability (sometimes referred to as mental handicap or mental retardation) was the main reason that convinced researchers that autism was a biologic condition, and not a psychogenic disorder caused by social circumstances and stressful life events. However, the association between intellectual disability is neither straightforward nor fully understood, although a few generalizations can be made. First, although the level of intellectual disability can vary from mild to profound, most cases tend to be in the moderate/severe range. Second, separating autism from profound mental retardation is difficult. Third, the likelihood of seizures is increased in those who have autism and intellectual disability. Fourth, although autism and related disorders cluster in families, there is no excess of intellectual disability alone in the family members of patients of autism. Fifth, compared with those without intellectual disability, patients with autism plus intellectual disability are more likely to have ritualistic behaviors and abnormal movements. Sixth, IQ is a reliable predictor of the long-term outcome of the disorder.
Association with epilepsy
As stated earlier, the occurrence of epilepsy and intellectual disability were the 2 main factors that convinced skeptics about the biologic origin of autism. Epilepsy occurs in at least 30% of cases of traditional autism, usually in the preschool years or around puberty. The most common type of seizures are of the complex partial type, although other types have also been described. The occurrence of autistic features tends to be higher in the epileptic syndromes of childhood, such as Landau-Klefner syndrome.
19
Also, certain genetic syndromes association with mental retardation, such as tuberous sclerosis (TS), are particularly associated with autism. For example, the prevalence of autistic features in TS has been stated to range from 30% to 50%. In those who are affected, the likelihood of having autism increases if the tubercles are located in the temporal region.20
Regressive Autism
In about one-fifth of children with autism, a history of regression is present.
21
, 22
Typically, children start developing normally, and then, around the age of 18 months to 2 years, lose their language and adaptive skills. A history of a precipitant, such as an infection, may or may not be present. In some children, the regression seems to coincide with the emergence of seizures. However, in general, there is no history of an obvious cause. In some children, the regression may be delayed when distinction from disintegrative disorder becomes difficult.23
When Should Autism be Suspected
From a clinical point of view, children who present to a pediatrician should be screened for ASD if they seem excessively shy, are socially awkward, have a language impairment, or seem to be obsessed with certain topics or interests. Also, any child who has intellectual disability or epilepsy should also be screened for autism. In addition, other conditions that should alert the pediatrician to screen for autism or an autism-related condition are language delay, severe hyperactivity, and obsessive-compulsive behavior.
Mental status examination
Every patient with ASD seen in primary care should have a mental status examination.
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Apart from observing and noting the core features of autism as indexed by social-communication deficits (eg, poor eye contact, absence of social smiling, problems with personal boundaries, language abnormalities) and restricted interests (eg, tendency to fixate on certain topics or activities, compulsive behaviors and rituals), the examiner should routinely evaluate for externalizing symptoms (eg, level of activity, aggressive behavior) and internalizing behaviors (eg, depressive symptoms, suicidal and self-injurious behaviors). In late adolescence and adulthood, particular attention should be paid to any signs of regression (eg, onset of psychotic symptoms, alteration of speech, emergence of catatonia).Physical examination
A brief medical examination should also be performed, including assessment of vision and hearing. Any dysmorphic features should be noted. Some children with autism may have an increased head circumference. A Wood lamp examination may be necessary to look for the typical skin stigmata of TS. Although a detailed neurologic examination is usually not necessary, any soft neurologic signs such as clumsiness should be noted.
Screening and screening instruments
The diagnosis of autism is based on obtaining a detailed developmental history and performing a systematic examination. Rating scales and structured interviews are commonly used to strengthen the process of clinical diagnosis, not to replace it. Although the instruments are accurate in diagnosing classic autism, they need to be interpreted with caution when autism is complicated by severe intellectual disability or when the symptoms co-occur with complex psychiatric disorders such as psychosis.
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Therefore, the gold standard of diagnosis should consist of collecting information in a systematic manner with rating scales, structured interviews, and observation schedules, and then performing a thorough clinical examination. The type of instruments selected depends on the time and the resources available. For example, ADI (Autism Diagnostic Interview), ADOS (Autism Diagnostic Observation Schedule), and the DISCO (Diagnostic Interview for Social and Communication Disorders), take hours to administer (3–5 hours if done properly) and require special training. Newer instruments that incorporate elements of a standard mental status examination in addition to autism-specific questions might be useful.24
In addition, diagnosis is made from the DSM/ICD criteria and not on the findings of a structured interview.26
It is also critical to have a multidisciplinary approach to the evaluation because children with autism may behave differently with different examiners and in different settings. At the minimum, the team should include a child psychiatrist, a speech and language therapist, a psychologist, and an educational consultant.Differential diagnosis and comorbidity
When assessing a child with suspected autism, the first question that needs to be clarified is whether the child is at a normal level of cognitive functioning. If the child has an intellectual disability, then it has to be decided whether the clinical features are the result of intellectual disability or autism or both. In brief, although there is global developmental delay in intellectual disability, the pattern of deficits is neither uniform nor global in autism. If the child is of normal intelligence, other conditions should first be ruled out, such as shyness, severe attention-deficit/hyperactivity disorder, anxiety and mood disorders, and psychotic disorders. Although a detailed description of each of these conditions is outside the scope of this article, referral to a child psychiatrist should be made if necessary.
27
- Volkmar F.
- Cook Jr., E.H.
- Pomeroy J.
- et al.
Practice parameters for the assessment and treatment of children, adolescents, and adults with autism and other pervasive developmental disorders. American Academy of Child and Adolescent Psychiatry, Working Group on Quality.
J Am Acad Child Adolesc Psychiatry. 2000; 39: 938
Summary
ASDs are more common than generally believed, occurring in as many as 1% of the population. Most patients with ASD are first referred for diagnosis to pediatricians and family practitioners. Although typical cases are easy to recognize, milder cases and those with comorbid psychiatric disorders can pose severe challenges. Despite the advances made in understanding the disorder, the diagnosis of ASD remains clinical. There is no biologic test for the diagnosis of autism. Although rating scales and structured interviews can help in clarifying the diagnosis, the eventual diagnosis remains clinical.
References
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Article info
Footnotes
The authors have no conflict of interest to declare.
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Copyright
© 2012 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
