There is no standard ‘type’ or ‘typical’ person with autism. Parents may hear more than one label applied to the same child: autistic-like, learning disabled with autistic tendencies, high functioning or low functioning autism. These labels don’t describe differences between children as much as they indicate differences between professionals’ training, vocabulary and exposure to autism (1)
In my first web paper I considered Attention Deficit Hyperactivity Disorder, and questioned whether its’ symptoms and underlying neurobiology should be considered a disorder, or rather simply a difference among humans’ nervous systems. In a further exploration of the idea of individuality within a diagnostically defined disorder, I have researched autism. By definition, autistic individuals present symptoms with varying degrees of severity. It is therefore considered a spectrum disorder, meaning that its’ “symptoms and characteristics can present themselves in a wide variety of combinations, from mild to severe (1).” A diagnosis of autism can result from any combination of its defined behaviors. In addition to this, there is a host of related disorders, in which some but not all symptoms of autism are present. These include Asperger Syndrome, Fragile X Syndrome, Rett Syndrome and Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS) (4)(2). Because of its characteristic breadth, autism is a good example of the implications of being seen as an individual within a group possessing a defined disorder. Current professional opinion stresses the importance of accurately assessing differences in neurological deficits, even if they present similar autistic symptoms. In other words, a child who appears autistic due to a lack of verbal and social interaction may appear this way for a variety of underlying reasons. There is evidence that some autistic individuals are capable of more joyful and more interactive lives than was previously believed, and an accurate diagnosis of their neurological deficiencies is essential in order to assess their potential and devise appropriate treatment. Autism is distinct from ADHD because it is a more debilitating disorder, but it is similar in that both are diagnosed through a collection of symptoms, the underlying biology of which is not fully understood. From this perspective, clinical methodology for the two disorders should be similar, making efforts to approach each potential diagnosis with as accurate an assessment of an individual’s physiology as is possible, given present limitations in understanding. A closer look at the symptoms and possible causes of autism will illuminate this argument.
Autism is a developmental disability that appears within the first three years of a child’s life. It is four times more common in boys than in girls, affects about 1 in 500 individuals, and is the third most common developmental disability in the U.S. Its’ impact on the brain is largely manifested through discrepancies and delays in social interaction and communication skills (1). Due to autism’s variety, its’ symptoms seem best understood when presented descriptively and with specific examples. Classic autism is defined as “impaired social interaction, problems with verbal and nonverbal communication and imagination, and unusual or severely limited activities and interests (2).”
The underlying cause of these external behaviors is best generalized as the result of sensory impairment. One web site describes autism in the following way: “autistic people tend to have unusual sensory experiences. These experiences may involve a sense being too sensitive, less sensitive than normal, and/or difficulty interpreting a sense (“agnosia”) (5).” The variety of behaviors stemming from this common theme can be direct opposites of each other. An autistic person may avoid being touched if they are hypersensitive in this area of sensory input, and an infant who arches its back away from a caregiver when being picked up is an early sign of autistic behavior. On the other hand, the infant may not register being picked up at all, and remain limp, which is the opposite problem. An oversensitivity to sound can result in sensory overload, physical pain, and a resultant tantrum from a normal sound like the vacuum cleaner, or, conversely, undersensitivity can result in the inability to hear and/or interpret words, so that verbal communication with others is affected (5),(4). Using under or oversensitivity as a parameter, the other behaviors described as autistic fall into place. These include:
Finally, autism often involves what is known as stereotypy or self-stimulatory behavior, defined as “repetitive body movements or repetitive movement of objects (6).” This type of behavior can involve any of the senses, and includes things like hand-flapping, tapping ears, scratching, rocking back and forth, smelling objects, placing body parts or objects in one’s mouth, or making repetitive vocal sounds. Theories again reference the distortion of sensory input typical to autism, suggesting that this type of behavior is due to hyper or hyposensitivity. A hypersensitive person uses these behaviors to calm himself from the sensory overload, while a hyposensitive person uses them because she craves stimulation. These behaviors are thought to release endogenous beta-endorphins, which induce feelings of pleasure (6).
Proposed theories on the causes of autism have ranged from viral to genetic, which, if accurate, could account for the variation in symptoms. Some research has focused on abnormalities of the brain structures of autistic people. Autopsies conducted for research purposes by Dr. Margaret Bauman and Dr. Thomas Kemper reveals that the amygdala and hippocampus of autistic people are densely packed with neurons, and that these neurons are smaller than those of the average person (3),(9). It is thought that the amygdala controls emotion and aggression, and is responsive to sensory input, and the hippocampus controls learning and memory. When the amygdala is removed in animals they exhibit social withdrawal and difficulty adjusting to novel situations, and when the hippocampus is removed they display self-stimulatory behaviors, all of which mimic autistic behaviors (9). In other research, Dr. Eric Courchesne has used magnetic resonance imaging (MRI) and found that lobules VI and VII of the cerebellum in autistic people are smaller than in non-autistic people (7). In a pattern of opposites typical of autism, he also found autistic people with larger than normal lobules. He has concluded that these parts of the cerebellum may be responsible for the ability to shift one’s attention, and the abnormal size of these lobules contributes to autistic people’s lack of this ability. However, autopsies of autistic individuals have not produced corroborating evidence of these lobules being smaller (7). Dr. Courchesne has also found differences in the size and number of purkinje cells in cerebral regions. These cells cause “programmed cell death,” which is the death of unnecessary neural tissue, a process that happens in early development (#3). A lack of purkinje could be responsible for the regions packed with neurons found by Bauman and Kemper. It is interesting to note that lack of purkinje cells and abundance of neural tissue could be an effect of autism, rather than a cause.
In addition to the above physiological abnormalities, there is evidence of a genetic link to autism. This is seen in the high incidence of two identical twins having autism, and a rare incidence of two fraternal twins having autism. A study conducted in Utah showed that nearly 50% of children born to autistic parents are also autistic. Another genetic link can be seen in the higher incidence of autism in boys than in girls (3, 4,8). There are many other theories. Exposure to the rubella virus during the first trimester of pregnancy, overgrowth and entrance into the bloodstream of the usually benign bacteria Candida albicans, and, although there is not yet any hard scientific evidence, pollutants in the environment and allergies or food sensitivities are all possible contributors to autistic behaviors (3),(4),(8). An interesting question about which I found no information is whether any research has attempted to link any of the proposed causes of autism with a specific pattern of severity in presented symptoms. Given both the breadth of possible causes and defined symptoms, this seems a logical next step.
Dr. Stanley Greenspan and his colleague Serena Wieder address the issue of treating developmental disorders like autism in their book, The Child with Special Needs. Their physiological concept is of a feedback loop consisting of three functional categories: sensory reactivity, sensory processing and muscle tone, and motor planning and sequencing. For them, treatment means “putting the feedback loop into working order by finding the parts of the system that are challenged and working to improve them (10).” These categories correlate with the basic concept of the nervous system that we have been working with, that of an input-output box with smaller boxes of neural connections that do not end outside the body. Because there is no medical test for diagnosing autism, great care should be taken in working with children who display symptoms to understand what may be really going on. Drs. Greenspan and Wieder comment that “a child may be diagnosed with autism…because he has difficulty relating to others, when his underlying problems are actually more specific and involve difficulty processing auditory information and a severe overreactivity to sound (10).” Here again the focus is on the external effect of the internally occurring sensory deficits. The authors connect the “external” problem with the “internal” problem by noting that “sensory reactivity or processing difficulties can cause a child to misinterpret emotional information from those arou#nd him, resulting in inappropriate- sometimes extreme- emotional reactions (10).” This astutely points out that the difference between viewing the sensory/processing difficulties as the autistic deficit versus viewing the emotional response as the deficit. In their view, the emotional response is a logical reaction from a frustrated child. This type of distinction makes a disorder like autism approachable with a plan of treatment. The Center for the Study of Autism takes a similar stance, citing a technique known as Sensory Integration to habituate autistic people to sensory input that they find painful or upsetting (4). Variations of this technique and many others suitable for approaching autism and other developmental disorders are central to Greenspan and Wieder’s philosophy of treatment. Along with other organizations dedicated to understanding and helping people with autism, the authors are optimistic that this approach to treating individuals will be successful: “Moving beyond the labels to an individual-difference approach opens the door to new possibilities for children. It seems clear that with an optimal intervention program tailored to a child’s individual differences, the possibilities are far greater than we had thought (10).”
The very definition of autism as a spectrum disorder implies that its’ diagnostic coherence could be subject to scrutiny, particularly if the underlying causes could be successfully defined. From this perspective, autistic individuals should be treated as just that- individuals- and their potential for more successful interaction and communication skills should be carefully considered. No person’s potential for a joyful existence should be underestimated.
2)Fact sheet from NINDS
3)paper by Dena Bodian from Neurobiology and Behavior 1998
4)Overview of Autism by Stephen Edelson, Ph. D., at the Center for the Study of Autism
5)Autism? What is it?
6)Stereotypic (Self-stimulatory) Behavior by Stpehen M. Edelson
7)The Cerebellum and Autism by Stephen M. Edelson
8)Genetics and Autism by Stephen M. Edelson
9)Autism and the Limbic System by Stephen M. Edelson
10)”The Child with Special Needs"by Stanley I. Greenspan and Serena Wieder. Massachusetts: Perseus Books, 1998.
| Course Home Page
| Back to Brain and Behavior
| Back to Serendip |
This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.