Changes to the DSM Autism Diagnostic Criteria
By Leanne Tull, BCBA
The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) debuted at the American Psychiatric Association (APA) annual meeting in May 2013. Since the publication of DSM-I in 1952, a standard review process has led to revised DSM editions over the past two decades. Advances in neurology, genetics, and behavioral science have expanded our knowledge of identification, assessment, and treatment of individuals with mental health disorders.
DSM revisions are the combined efforts of a work group comprised of clinical experts in various areas of diagnosis. From 2008-2010, the DSM-5 Task Force and Work Group members have examined the current edition (DSM-IV-TR) to determine:1) what components meet the needs of clinicians; 2) what components do not meet the needs of clinicians; and 3) how to address these needs (APA, 2011). The revision process also includes conducting extensive literature reviews, attending a series of planning conferences in partnership with the World Health Organization and the National Institutes of Health, and soliciting feedback from professionals and educators (APA, 2011; Wing, Gould, & Gillberg, 2011). The result of this process includes changes in the criteria for the diagnosis of Autism Spectrum Disorders (ASDs), and these changes have certainly evoked some questions, concerns and confusion among parents, professionals, and educators.
The DSM-IV-TR describes Pervasive Developmental Disorder (PDD) as a “diagnostic umbrella”, with five subtypes: 1) Autistic Disorder; 2) Asperger’s Disorder; 3) Rett’s Disorder; 4) Childhood Disintegrative Disorder; and 5) PDD-NOS (“Not-Otherwise-Specified”). The aim of the new DSM-5 is to improve diagnostic criteria that are not precise, such as combining subgroups of ASD and reducing diagnoses currently called “Not Otherwise Specified”.
The basic triad of impairments underlying Autism has included: impairment of social interaction, impairment of communication, and restricted repetitive and stereotyped patterns of behavior. The DSM-5 reduces this triad to a dyad – impairment of social interaction and communication (now be regarded as one combined domain) and restricted repetitive and stereotyped patterns of behavior (Wing et al., 2011). Although there is a reduction in underlying impairments, the latest diagnostic criteria expands to include four criterion: Criterion A denotes the ‘social communication deficits’ domain, consisting of three items, all of which must be met to satisfy this criterion; Criterion B denotes the ‘fixated interests and repetitive behaviors’ domain, consisting of four items, of which at least two must be met to satisfy this criterion; Criteria C and D concern ‘symptoms existing in early childhood’ and ‘symptoms impairing functioning’, respectively (APA, 2011). To diagnose ASD, all of the four criteria must be met.
DSM-5 Priorities: Increasing Diagnostic Validity and Clinical Utility
Making the manual useful to clinicians diagnosing and treating people with mental disorders is the highest priority. In addition to changes noted above, the DSM-5 incorporated a dimensional assessment approach, allowing clinicians to measure both the presence and the severity of ASD symptoms as: “very severe,” “severe,” “moderate”, or “mild" in the two symptom domains of ‘social communication’ and ‘fixated interests and repetitive behaviors’ (APA, 2011). This dimensional assessment may address some site-based and clinician-based differences that affect information used to make best-estimate clinical (BEC) diagnoses of ASDs.
The diagnostic validity and clinical utility of DSM-IV-TR diagnostic criteria and implications for revisions of new diagnostic frameworks, such as the DSM-5, are currently being researched and evaluated. Lord, Petkova, Hus, Gan, Lu, Martin, and colleagues (2012) conducted a study to determine the relationship between site-based and clinician-based differences that affect BEC diagnoses of different ASDs (Autistic Disorder, PDD-NOS, and Asperger’s Disorder) across 12 university-based sites. Using DSM-IV-TR diagnostic criteria, 2102 participants (probands), ages 4 to 18 years, were evaluated, with the recruited help of 47 psychologists, 6 physicians (3 psychiatrists, 2 pediatricians, and 1 clinical geneticist), and 3 master’s level clinicians. Each proband was administered the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, Risi, 1999), a hierarchy of cognitive tests, and parent completed questionnaires and interviews.
Results of the study revealed, significant site differences across BEC diagnoses of specific ASDs. For children with moderate to severe social communication deficits, the most important factor for BEC diagnosis was verbal IQ. If children had an ADOS score of 12 or greater and verbal IQ of less than 85, then they received a diagnosis of ‘Autistic Disorder’ (Lord et al., 2012). In contrast, children with an ADOS score of 12 or greater and a verbal IQ of greater than 85 were affected by the site-based and clinician-based differences (Lord et al., 2012). Striking differences in verbal IQ cut-off points and whether or not IQ was associated with differentiating Autistic Disorder from PDDNOS/Asperger’s Disorder or differentiating Autistic Disorder/PDD-NOS from Asperger’s Disorder demonstrated the hypothesized variation in how BEC diagnoses within ASDs are assigned to individual children. In addition to ADOS scores and verbal IQ, children’s ages and parent-reports about repetitive behaviors, communication abnormalities, and hyperactivity, influenced diagnoses at many sites. More precise diagnostic criteria specific to cognitive and language functions might have made these distributions more consistent.
In a study by McPartland, Reichow, and Volkmar (2012), the sensitivity and specificity for proposed DSM-5 diagnostic criteria were evaluated using field trial symptom checklists. A sample of 657 individuals who received a clinical diagnosis of an ASD (Autistic Disorder, n=450; Asperger’s Disorder, n=48; PDD-NOS, n=159) using a former DSM edition, were evaluated using field trial symptom checklists. The field trial evaluations were conducted by 125 clinicians across 21 international sites. Field trial symptom checklists were as follows: a) individual field trial checklist items (e.g., nonverbal communication); b) checklist items grouped together as described by a single DSM-5 symptom (e.g., nonverbal and verbal communication); c) individual DSM-5 criterion (e.g., social communicative impairment); and d) overall diagnostic criteria (McPortland et al., 2012).
Results specific to sensitivity revealed that 398 of 657 clinically diagnosed cases met the DSM-5 criteria for ASD, with 259 cases failing to meet diagnostic entry. In terms of specificity, the proposed DSM-5 criteria accurately excluded 262 of 276 individuals (McPortland et al., 2012). Further exploratory analyses showed that the proportion of individuals (274 of 393 cases) with lower cognitive ability (i.e., IQ < 70) meeting DSM-5 criteria was significantly higher than the proportion of individuals (109 of 237) with higher cognitive ability (i.e., IQ ≥ 70) meeting DSM-5 criteria (McPortland et al., 2012). Overall, results show that DSM-5 revised criteria improve specificity, when compared to earlier DSM editions. Although a more stringent diagnostic threshold may alleviate or reduce over-diagnosis and misdiagnosis, it may also deny individuals with “sub-threshold disability” (i.e., individuals previously diagnosed with Asperger’s Disorder) access to services.
DSM-5 Autism Diagnostic Criteria: Removing Asperger’s Disorder
The “disappearance” of Asperger’s Disorder has created a lot of confusion. According to researchers (Ghaziuddin, 2010; Kaland, 2011), DSM-IV-TR Asperger’s Disorder and Autism diagnostic criteria were vague and difficult to use. For example, ‘language delay’ was not operationally defined. Language deficits typically displayed by individuals with Asperger’s (i.e., communication that is one-sided and pedantic) are typically masked by fluent grammatical skills (Wing et al., 2011; Kaland, 2011). As well, DSM-IV-TR differences in social deficits across Asperger’s Disorder and Autism were not clearly delineated. Social deficits displayed by individuals with Asperger’s (i.e., not being able to understand the subtle and unwritten rules of social interactions) often outweigh social initiations or attempts to interact with others (Wing et al., 2011; Kaland, 2011). As a result (and noted earlier), the distinction used most often between a diagnosis of Asperger’s and Autism is that early language and cognitive functions are not delayed in individuals with Asperger’s, as opposed to individuals with Autism for whom the reverse usually is the case (APA, 2011).
Currently, we do not know whether Asperger’s Disorder is genetically identical to, or distinct from, Autism. Some researchers argue that the lack of the identification of biological markers provides debate in regards to the reliable distinction between subtypes of ASD (Baron-Cohen, & Klin, 2006; Ghaziuddin, 2010; Worley & Matson, 2012). To many parents, professionals and educators, ‘Asperger’s Disorder’ describes a population of individuals who may respond to a different set of interventions than those with typical Autism. It is important to note that identification of the disorder has increased awareness of high functioning forms of Autism and resulted in the development of complex interventions such as, advanced social skills training groups (Barnhill, Cook, Tebbenkamp, & Myles, 2002; Tse, Strulovitch, Tagalakis, Meng, & Fombonne, 2007; Webb, Miller, Pierce, Strawser, & Jones, 2004), behavior analytic self-management techniques (Dorminy, Luscre, & Gast, 2009; Tiger, Fisher, & Bouxsein, 2009; State & Kern, 2012), and modified Cognitive Behavioral Therapy (CBT; Reaven, Blakeley-Smith, Culhane-Shelburne, & Hepburn, 2012; Wood, Drahota, Sze, Har, Chiu, & Langer, 2009).
Diagnostic requirements for service eligibility already vary widely across state and government funded agencies, with some including Asperger’s Disorder and others not. Many individuals and families affected by Asperger’s Disorder now fear losing a diagnosis could also result in a loss of benefits and services. Fortunately, the DSM-5 has included a note to guard against this, saying, individuals with a well-established DSM-IV diagnosis of Autistic Disorder, Asperger’s Disorder, or PDD-NOS should be given the diagnosis of ASD (APA, 2013). In addition, researchers anticipate that individuals who display insufficient signs to meet the criterion of ‘restricted, repetitive patterns of behavior, interests and activities’ (i.e., individuals previously diagnosis with PDD-NOS) or individuals who display problems using verbal and nonverbal communication for social purposes, without delayed cognition (i.e., individuals previously diagnosis with Asperger’s Disorder), may be moved into the new category of ‘Social (pragmatic) Communication Disorder’ (SCD) (Lai, Lombardo, Chakrabarti, & Baron-Cohen, 2013). Optimistic consumers hope there will be just as many services available for individuals diagnosed with SCD as there are for its well-recognized cousin, Autism.
DSM-5 Algorithm: Evaluation of Impact on Autism Prevalence Rates
With an estimated prevalence of 1 in 88 children, ASD is one of the most common neurodevelopmental disorders; however, the changes in DSM-5 diagnostic criteria may address a criticism of prior DSM editions that have been associated with increased prevalence rates (McPortland et al., 2012). Several studies have explored the proposed DSM-5 algorithm to evaluate the impact on prevalence of diagnosis relative to DSM-IV-TR.
In a study by Worley & Matson (2012), a total of 360 participants were separated into groups according to the DSM-IV-TR and DSM-5 diagnostic criteria for ASD. All participants were first assessed using the DSM-IV-TR diagnostic criteria. At least three items had to be endorsed (i.e., two impairments in social interaction and one in either communication or repetitive, stereotyped, or restricted patterns) to satisfy DSM-IV-TR diagnostic criteria for a diagnosis of ASD. Using the DSM-IV-TR, 180 participants met criteria for ASD and 166 did not meet criteria (Worley & Matson, 2012). Next, all participants were assessed according to the DSM-5 diagnostic criteria. At least three impairments in socialization and two in restricted interests and repetitive behaviors needed to be endorsed to satisfy DSM-5 diagnostic criteria for a diagnosis of ASD. Using the DSM-5, 121 participants met criteria for ASD and 225 did not meet criteria (Worley & Matson, 2012).
For the purpose of statistical analyses, participants were reclassified into three groups: 1) participants meeting diagnostic criteria for ASD according to the DSM-5 (n = 120); 2) participants meeting criteria for an ASD according to the DSM-IV-TR (n = 52); and 3) participants not meeting diagnostic criteria for ASD according to either DSM-IV-TR or DSM-5 were classified as the control group (n = 109) (Worley & Matson, 2012). The investigators had hypothesized that significant differences would surface between the DSM-IV-TR and DSM-5 groups on all core symptoms (i.e., nonverbal communication/ socialization, social relationships, and insistence of sameness/ restricted interests), however, nonverbal communication/ socialization was the only core symptom that contributed to the significant difference between the DSM-IV-TR and DSM-5 groups (Worley & Matson, 2012). Participants in both the DSM-5 group and the DSM-IV-TR group scored significantly higher (i.e., indicating more symptoms of ASD) than participants in the control group. These findings suggest that fewer children will meet diagnostic criteria, which may decrease the trend of ASD incidence and prevalence rates once the DSM-5 manual is utilized clinically over an extended period of time.
In light of predictions that the prevalence of ASD diagnoses will dramatically decrease with the introduction of the DSM-5 criteria, some researchers have explored modifications to the proposed DSM-5 algorithm. Matson, Hattier, and Williams (2012) explored changes in prevalence using a diagnostic criteria set which was modified slightly from the DSM-5 criteria (Modified-1 criteria) and again using a set of criteria which was adapted even a bit more (Modified-2 criteria). The Modified-1 criteria included all DSM-5 criteria with the exception of requiring only two out of three, rather than three out of three, impairments in social communication and social interaction (Matson et al., 2012). The Modified-2 criteria were slightly less stringent than the Modified-1 criteria, and required at least two out of the three impairments in social communication and social interaction and at least one out of four, rather than two out of four, impairments on restricted, repetitive patterns of behavior, or interests (Matson et al., 2012).
Results of the study suggest that use of Modified-1 criteria will mark an estimated 33.77 % decrease in the prevalence of ASD when compared to the DSM-IV-TR (Matson et al., 2012). Should the new DSM-5 criteria be loosened further (Modified-2), an estimated 17.98% drop in ASD diagnoses will be observed when compared to the DSM-IV-TR (Matson et al., 2012). Although the definition of Autism, as a neurodevelopmental disorder, has certainly evolved, studies conducted by Matson and colleagues (2012) and others (Worley & Matson, 2012; McPortland et al., 2012) that predict a large change in prevalence rates from the DSM-IV-TR to the DSM-5, should not be unexpected.
Despite these changes to the DSM-5 diagnostic criteria, at least one critical point remains the same: early detection of autism and timely, high-quality, science-based intervention is key to promoting optimal independence for individuals with ASD. The Center for Disease Control and Prevention provides a list of possible “red flags” for Autism at http://www.cdc.gov/ncbddd/autism/signs.html. Parents and caretakers who have concerns about the social or communicative development of their child can review these “red flags” with their child’s health care provider as part of their determination of whether or not additional testing is warranted.
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