One version of the traditional spectrum is as follows:
|Autistic Disorder (Classic)||Usually low-functioning, nearly half are diagnosed with mental retardation|
|Rett’s Disorder||Degenerative disorder limited to girls, linked to specific genetic markers|
|Disintegrative Disorder||Similar to Rett’s, child “regresses” after two to three years of seemingly normal development|
|Asperger’s Disorder [Syndrome]||Impaired social skills, often physically awkward, no substantial delay in language|
|Pervasive Developmental Disorder — Not Otherwise Specified||Meets most criteria, but not easily classified as another disorder|
Because Rett’s and Disintegrative Disorder involve a measurable loss of brain function, as revealed by magnetic resonance imaging (MRI), some have argued that these conditions are physically different from autism disorders. This is an area open to debate, however.
As Olga Bogdashina reminds us, every autistic individual is different, whether we use the spectrum metaphor or not:
The ways in which any of the features are manifested vary from one child to another, and for the same child different aspects of the behavior pattern may vary at different ages. Usually no one person has all the characteristics at the same time or at the same degree of severity. (Bogdashina, 2006, p. 26)Some autistic children sit silently, others are more likely to scream and run about a room. There is no one “autism” parents and educators must address, just as no two “neurotypical” children are the same.
For many parents, educators, and clinicians, the term “spectrum” refers primarily to the social and linguistic skills of ASD individuals. At one extreme, we find the child apparently isolated from the world. At the other extreme we have gifted students with curious preoccupations. Both might be considered “autistic” — though there’s little doubt they experience their worlds, especially social interactions, differently.
Clinicians and education experts use several terms to describe spaces along the autism spectrum:
As autism is a spectrum disorder and its manifestation varies from individual to individual, it is no wonder, therefore, that many ‘non-official’ but widely accepted descriptions have emerged: high-functioning autism (HFA), low-functioning autism (LFA), ‘mild autism,’ ‘moderate autism,’ ‘severe autism,’ ‘autistic traits,’ ‘autistic tendencies.’ It is necessary to note that these terms are subjective. There are no clinical definitions of words such as ‘high-functioning autism,’ ‘low-functioning autism,’ ‘mild’ or ‘severe’ autism. However, because autism is so wide ranging, professionals may use terms like these to describe where on a continuum they believe an individual’s abilities may lie. (Bogdashina, 2006, p. 27)The terms adopted by clinicians, officially endorsed by the American Psychiatric Association or not, are attempts to capture individual differences. An ASD individual might be an example of “classical autism” or a gifted student with Asperger’s syndrome, able to “blend in” with peers.
Asperger’s specialist Tony Attwood has written about the different ways clinicians and researchers discuss ASDs. As Attwood notes, there is an ongoing effort by the psychiatric field to refine definitions and understandings of ASDs.
There was a recognition in both diagnostic manuals [ICD-10, World Health Organization 1993 and DSM-IV, American Psychiatric Association 1994] that autism, or Pervasive Development Disorder, is a heterogeneous disorder and that there appear to be several subtypes, one of which is Asperger’s syndrome. (Attwood, 2007, p. 36)Psychologist Alexander Durig’s 1996 book Autism and the Crisis of Meaning asks if there are gradations of autism. This book was published just as clinicians were beginning to adopt the spectrum metaphor.
Traditionally, we have viewed individuals as either Autistic, high-functioning Autistic, or normative. But does the gradation from Autistic to high-functioning Autistic have to stop somewhere? ... In other words, could there possibly be some people with strong Autistic perception who are so high functioning that they have always appeared, for the most part, normative to others? (Durig, 1996, p. 99)
|Possible Range of Inferences||(I-) Induction None to Just Below Norm||(I) Induction Norm||(I+) Induction High to Super|
|(D-) Deduction Below Norm||Mentally Retarded perhaps also Autistic||Personable Perception Down’s Syndrome||Personable Savant Con Men/Women|
|(D) Deduction Norm||Pure, High-Functioning, Slightly (I-/D) Autistic||Normative Individual||Slightly Personable High-Profile Public Figure, Politician, Businessperson|
|(D+) Deduction High to Super||Autistic Savant||Slightly (I/D+) Autistic||Genius|
Durig has taken the spectrum notion further by suggesting what we consider autism is merely a “differed” way of perceiving the world. Individuals might have an “autistic perception” that gives them different insights.
[W]e might consider the notion that there is not actually such a thing as Autism as much as there is a phenomenon of Autistic perception that is experienced in varying gradations. In current terminology, a person with Autism is actually a person with very strong Autistic perception. (Durig, 1996, p. 98)Durig’s conclusions are thought provoking. What if the underlying conditions causing what we consider “autism” are liniked to other characteristics?
The possible existence of slight Autism may explain a wide range of phenomena that are often chalked up to learning disabilities, mental illness, sociopathy, eccentricity, tempermental [sic] creative genius, or saintliness. (Durig, 1996, p. 102)There is little doubt that dozens of “spectrums” comprise human behavior. We could, and have, developed dozens of scales describing our traits. If these scales help us understand and appreciate each other, then scales serve an important purpose. Individuals with ASDs are different. Placing a person’s traits on a scale is merely a way to explain those differences.
We must never forget that people aren’t scales, numbers, and other measures. When we treat a student as a composite of scores instead of an individual, we lose sight of the things that matter most.
Difference and Cause
If there are observable differences among ASD individuals, then it seems likely that there are different underlying causes of the traits we classify as “autism.” Some scientists point to a list of causes indicating how these differences might originate.
We are beginning to find genetic markers for ASDs. As Barry R. Tharp, M.D., writes in Autism Spectrum Disorders:
We assume that autism is a syndrome with many etiologies.... This lack of a single etiology behooves the physician to initiate a thorough neurologic and genetic evaluation after making the diagnosis of autism spectrum disorder. Approximately 10%-20% of children with autism spectrum disorders (ASD) have a definable neurodevelopmental genetic syndrome; this number is likely to increase as more sophisticated chromosomal analyses become clinically available (Shevall et al. 2001). (Ozonoff et al., 2003, p. 111)The list of suspect causes is lengthy. Each cause might affect a different part or parts of the nervous system, especially brain functions. With so many underlying causes for what we label as ASDs, a spectrum of symptomologies exists.
- Chromosomal syndromes:
- Fragile X
- Angelman syndrome
- 15q duplication
- Down syndrome
- Ring 20
- Rett disorder
- Neurocutaneous syndromes
- tuberous sclerosis
- Syndromes without known chromosomal abnormality
- CHARGE association
- Congenital/acquired infections
- In utero drug/chemical exposure
- valproic acid
- Inheritied metabolic disorders
- hypoxic-ischemic encephalopathy
Can we group developmental disorders together, as a spectrum? The Autism Society of America explored this issue in 2006:
Some professionals and families believe that the definition of autism should be inclusive of diagnoses such as Asperger’s and other Pervasive Developmental Disorders. Proponents of this view may argue that since there are no biological tests for either autism or Asperger’s, it is difficult to determine a diagnosis. They may further extend their argument into the service arena, as schools, insurance companies and social service agencies all use diagnostic guidelines for eligibility criteria. To obtain services, an individual must meet guidelines which usually do not recognize Asperger's as a form of autism. The family or individual, therefore, is unable to receive services because he does not possess the correct label.The spectrum metaphor and the myriad of diagnostic terms applied to developmental disorders has resulted in a debate: where are the boundaries between disorders?
Those who believe Asperger’s is not a form of autism cite the current DSM-IV which clearly states that Asperger's is a distinct diagnosis. They argue that by creating a distinction between autism and Asperger’s, one paves the way for more appropriate education and treatment. Other professionals argue that there are significant differences in early history and outcome between an individual with autism and one with Asperger’s. (Autism Society of America Web site, 2006)
Daniel Rosenn, M.D., developed a triagular diagram of the autism spectrum (1997). This diagram is now ubiquitous in texts and presentations on Asperger’s syndrome. Stephen Shore’s autobiography Beyond the Wall (2003) makes use of this diagram to illustrate where Shore places himself on the spectrum.
This diagram poses a problem, according to some clinicians. Rosenn and many others place HFA and AS together, implying there is no distinction. Research, however, does show a difference — but these findings depend on how autism is defined.
Some studies have found differences between individuals with diagnoses of “high-functioning autism” and those with Asperger’s syndrome. Patricia Howlin compiled the differences from various studies for comparison.
Howlin’s meta-analysis of more than a dozen studies presents the following findings:
Cognitive and Language Delays
In general, individuals diagnosed by clinicians with HFA experienced more significant language delays than those diagnosed with AS. By their late teens, language abilities are comparable between the groups.
A second distinction made by the DSM-IV concerns cognitive ability. While some individuals with autism experience mental retardation, by definition a person with Asperger’s can not possess a “clinically significant” cognitive delay. This is not to imply that all individuals with autism also have mental retardation. Some do and some do not, but a person with Asperger’s possesses an average to above average intelligence. (Autism Society of America Web site, 2006)The cognitive delays associated with HFA are somehow overcome in time. This means observable differences between HFA and AS are more pronounced before the teenage years.
Behavioral and Psychiatric Issues
Studies analyzed by Howlin recorded a far greater incidence of psychiatric and behavioral issues among AS individuals than those diagnosed with HFA. While the HFA individuals were more rigid, literal, and socially limited, the AS individuals had learned to not only adapt but to manipulate and create with a great deal of skill.
The HFA individuals liked organized routines. Behavior issues including outbursts were usually linked to changes in routine. AS behavior issues were less defined by the studies analyzed, but included verbal and physical outbursts. Externalized aggression might be a differentiating characteristic, according to some researchers.
Depression is more common among AS individuals than the general population. In my own observations and experiences, AS individuals do have a greater awareness of social situations than those diagnosed as HFA. I believe it is likely that this greater social awareness leads to a greater sense of separation and isolation. Laura Schreibman offers a similar explanation for this difference:
They [AS individuals] know they have to be taught how to socialize in ways that come so naturally and effortlessly for other people. In fact, two-thirds of adolescents with Asperger’s have a secondary mood disorder. In contrast, it is more likely that a child with high-functioning autism will see his accomplishments as successes and be happy about them. (Schreibman, 2005, p. 62)
Currently, it is impossible to prove AS and HFA are neurologically different. Though differences between AS and HFA individuals are observed during youth, those differences seem to fade over time. We do not know why this is.
Early-history differences are evident between the disorders, with children with Asperger syndrome showing less severity and better language ability in the preschool years than children with HFA, by definition (Ozonoff et al. 2000). Follow-up studies demonstrate similar trajectories in outcome, however…. Similarly, Ozonoff et al. (2000) found that children with Asperger syndrome required fewer years of special education and had a slightly better outcome than children with HFA, but overall found very few differences between the subtypes….Though the performance differences fade, the distinctions found by Howlin do remain. It could be that HFA individuals learn to “mimic” normal behaviors over time, but only to the extent they match the social skill levels associated with Asperger’s Syndrome.
[T]he jury is still out on whether the two are functionally different… (Ozonoff et al., 2003, p. 10)
A Personal View
As I explore autism and the spectrum, I increasingly view the diagnoses as distinct. I do not view HFA as synonymous with AS, nor am I certain the underlying neurological conditions are the same. Experts trying to link attention deficit / hyperactivity disorder to autism are complicating the issues even further. When the spectrum starts to include ADHD and something I have heard a presenter call “minimal AS” we make it more difficult for the public to understand the disorders we group together as ASDs. I fear that because “the spectrum” is attracting researchers and clinicians, there is a rush to broaden the spectrum metaphor.
If we find medical conditions that allow for clear distinctions between disorders, I think we will be much closer to appreciating individuals with ASDs. Such discoveries will allow us to pursue the best treatment and prevention options for each unique disorder.