Another firestorm of controversy was unleashed recently as experts continue to argue over proposed changes to the diagnosis of autism and related disorders. The American Psychiatric Association has proposed changes to the Diagnostic and Statistic Manual of Mental Disorders (DSM) for the fifth edition that would effectively consolidate Autism, Asperger’s Disorder and Pervasive Developmental Disorder Not Otherwise Specified into a unified diagnosis of Autism Spectrum Disorder. The changes come, in part, because of the APA’s belief that these disorders share common set of behavioral manifestations that are reliably differentiated from non-autistic disorder; but not well differentiated from each other.
Reasons For The Autism Diagnosis Criteria Change:
In the published rational, that APA stated “A single spectrum disorder is a better reflection of the state of knowledge about pathology and clinical presentation; previously, the criteria were equivalent to trying to ‘cleave meatloaf at the joints’.” This belief reflects emerging data that several similar brain regions develop in a pathological fashion in all three conditions and underlie the similarities between the conditions.
Autism Diagnosis Criteria Change Consequences:
However, the change in criteria may have other consequences. Fred Volkmar, MD, director of the Yale Child study Center and a leading expert in the field released results from his upcoming study that posited that changes in criteria could lead to as many as 50% of subjects in previous studies being eliminated from the spectrum and facing an end to needed services. While others have challenged this assumption, there is little doubt that a more narrow definition is being sought in part to limit the expansion of children meeting criteria for one of the pervasive developmental disorders. The CDC indicates that current estimates of autism and related disorders is about 1:150 children. However, studies have reported rates as high as 1:90 depending on the methods used in establishing the diagnosis.
Other experts in favor of the new DSM criteria contend that since some states do not provide the same level of care to children with PDD NOS and Asperger’s Disorder, rolling these conditions into an Autism Spectrum Disorder may actually increase access to care in some states.
How This Changes The DSM:
What seems to be lost in this discussion is the paradigm shift proposed to the structure of the DSM. Historically, most categories of disorders (such as Depressive, Anxiety, Amnestic, Substance Use, etc) are made based on behavioral characteristics as opposed to objective data or lab findings and all have maintained a “Not Otherwise Specified” category to allow for partial symptom presentations or atypical patterns that would still fall under the general heading. This format is consistent for the current range of Pervasive Developmental Disorders including autism. The new spectrum model is a departure from existing diagnostic nomenclature and the rational for this has not been explained. Imagine if spectrums were used for all conditions. Depressive Spectrum Disorders could range from a bad week on one end to inpatient hospitalization and suicidal ideation on the other. Researchers would simply treat them all as a continuum of severity. This does not happen mainly because differences in the onset, treatment and prognosis of each depressive disorder are very different even though the characteristics of dysphoria, loss of interest and behavioral changes may be similar. Clearly differences in diagnoses within categories are possible based on factors other than behavioral characteristics.
Supporters of the new DSM criteria may also be undervaluing the neurological and genetic markers currently under study. Recent evidence has suggested high rates of seizures and EEG abnormalities in autism and PDD NOS not seen in Asperger’s syndrome. Numerous genetic disorders have now been shown to have increased risk for autistic symptoms though none have been shown to have increased risk for Asperger’s Disorder. Accelerated head growth, ventricular abnormalities and pathological development of the language centers are all commonly found in autism and PDD, though not frequently present in Asperger’s Disorder. Conversely, neurological conditions that impact right hemisphere function show marked similarities to the nonverbal learning difficulties found frequently in Asperger’s Disorder. Even birth order, high risk pregnancies and prenatal complications are over-represented in autism and PDD NOS though all these biological markers were not considered in the spectrum model currently proposed.
Ultimately, continued research is needed to evaluate the similarities and differences in these conditions and many of us in the field are concerned that lumping related conditions together will weaken this process and potential our understanding of the root causes of these disorders. However, there is no denying that the ongoing discussions related to changes in the diagnostic nomenclature have brought needed attention to escalating rates of these diagnoses and the need for standardization.