The Etiology of Autism
Autism is a syndrome that is characterized by the impairment of social interaction skills, verbal and nonverbal communication, and a decreased interest in participating in a variety of activities. In 1943, Kanner, the man who is attributed with the identification of this disease, hypothesized that autism might be a biological disorder as opposed to a psychological one. Numerous studies have been conducted supporting Kanner’s hypothesis. These studies have ranged from examining the effects of rubella to investigating certain purine metabolic disorders as possible etiological agents. Recently, the areas of neuroanatomy, neurochemistry, and genetics have played a crucial role in developing a clearer picture into the etiology of this disease. Upon exploring the biological aspects of autism, the fields of neuroanatomy, neurochemistry, and genetics have offered new insights concerning their association with the onset of this disease.
Neuroanatomy is one of the latest fields involved in uncovering the possible causes of autism. Many past studies conducted in this area found that autistic patients had enlarged lateral ventricles, however, this abnormality didn’t reveal any damage to a specific anatomical site. The most recent studies conducted on the cerebella of autistic patients showed much more dramatic results. In one specific experiment conducted by Dr. Courchesne, the cerebellar lobules of eighteen autistic patients were compared with the lobules of twelve subjects within a normal control group.
The eighteen autistic patients were chosen on the basis that their autistic state was "... not complicated by severe mental retardation, cerebral palsy, epilepsy, genetic abnormality, other neurologic disease, or the use of anti-psychotic medication" (Courchesne, 1349). Dr. Courchesne conducted this experiment by taking magnetic resonance images from all of the subjects and then specifically examining the vermal lobules of the cerebellum. Courchesne directed his focus on the vermal lobules of these subjects based on a previous study he conducted on a non-retarded, autistic individual who displayed severe underdevelopment of vermal lobules VI and VII. In order to compare the differences between the scans, Courchesne made tracings of the scans and superimposed these tracings according to whether the subject was in the normal control or the autistic group. Tracings were only made of vermal lobules I-V and VI-VII, respectively. Tracings of vermal lobules IX and X weren’t taken because the MRI scans didn’t display well-defined boundaries for them.
Upon comparison of the control tracings and the autistic tracings, Courchesne found that "…vermal lobules VI-VII of the patients with autism were found to be significantly smaller than those of the controls…lobules I to V (the anterior vermis) were similar in size in the autistic and normal groups" (1350). Due to the correlation of the underdeveloped vermal lobules VI and VII...