Biology 202

2006 First Web Paper

On Serendip

Perhaps behaviors linked with autism are simply attributed to the extreme variations in brain structure that is present among all humans. However, there is a level of consistency of symptoms among those diagnosed as autistic and the numbers of children diagnosed is rising. In the 1980's, 1 in every 10,000 births were diagnosed with autism compared with 1 in 166 births in 2003 (1). Although some of this increase may be due to higher awareness of the disorder, this theory does not account for a 500% increase in diagnoses. Such an increase has spurred a great deal of research on the topic. Still, there is little understanding of what causes the condition.

Autism is believed to be caused, at least partially, by genetic factors. One study has explored the possibility that a gene that codes for a peptide hormone which was shown to prolong the life of neurons in rats may have a premature stop codon in people with autism (2). In general, the autistic brain is found to have noticeable differences from a "normal" brain including increased brain volume. However, it is unclear what genes are responsible for these differences, especially since there must be a large number of genes coding for the structures of the brain. The probable multigenic quality of autism accounts for the wide range of severity of symptoms (3).

In light of the fact that autism is manifested in many different forms, patients are diagnosed with an "Autistic Spectrum Disorder". These disorders are grouped together because each fundamentally deals with problems communicating socially. Some people with autism may not be able to communicate verbally while others have no verbal language difficulty but cannot process social cues like body language (4). Though diagnoses of ASD show similarities with classical autism, there remains difficulty in categorizing people under an umbrella term.

Specifically, education of children with Autistic Spectrum Disorders requires understanding of individual children beyond a diagnosis. For example, children diagnosed with autism are not necessarily mentally retarded and when faced with problems in school my simply need a different learning approach than students in the mainstream in order to excel. Autistic people typically exhibit interest in detail, so when other students or a teacher are not interested in that level of detail, the autistic student can be frustrated (4). Likewise, a student with a milder form of autism who has an above average IQ and is "high-functioning" but is having trouble in school may need accommodations in order to carry out his or her potential. However, there is question if children with autistic disorders can receive the education they need in an environment with "normal" children.

Autistic people are considered to be unable to empathize or have trouble empathizing with other people, depending on the severity of the case along the spectrum (5). Instead, they are thought to have strong "systemizing" tendencies. It is these tendencies that contribute to an obsession with details and even rituals. Absorption in a specific interest therefore isolates the person from others and prevents him from understanding social situations. When other children cannot understand why an autistic peer does something insensitive, the autistic child can become even more isolated.

Among information about brain differences between autistic people and non-autistic people is that in those with autism, dendrites are shed around the onset of symptoms therefore losing connections between neurons (6). This supports new information regarding "mirror neurons". These specific types of neurons are responsible for the brain being able to understand what other people are doing. For example, when a person watches someone else wave his hand, mirror neurons fire in the observer's brain as if to make his own hand wave. With this information in mind, it is believed that autism could be caused by "broken" mirror neurons (7). Without the ability to process social languages due to a lack of certain brain structures, autistic people must learn to imitate others and abide by social norms. Because behavioral training and schools particularly tailored for autistic students have had success in teaching social skills, it seems that environment can override deficits in brain structure.

Some theorize that autism is the manifestation of the "extreme male brain" (5). This argument states that women are more likely than men to empathize, or put themselves into another person's shoes and less likely to "systemize" by making schedules and routines, for example. Males are more likely to do the opposite, therefore those with autism exhibit qualities of the male brain to an extreme. This is interesting because autism is far more prevalent among males (9). As we see when autistic children are taught to recognize social cues, it seems that culture can affect the brain therefore altering male and female brains and causing them to reflect the differences society imposes upon them. However, evidence shows that much of these differences are apparent even at very young ages when it would seem that culture has not yet had a chance to effect children. For example, at 12 months of age, girls show more eye contact than boys, reflecting more of an affinity for social connection. Another example is that when a female rat is injected with testosterone it can travel through a maze more easily than a female rat without injected testosterone (5). Females with autism exhibit the same tendencies as males. With this theory in mind there must be something that causes a female person's brain to become more "male." Differences between the male and female brain add some understanding to the roots of autism. Still, it is unknown exactly how brain structures cause these extreme systemizing tendencies.

Although autism is believed to be strongly linked to genes, it is also believed that outside factors may be linked as well (10).One controversial theory is that the presence of the preservative thimerosal in vaccines administered to infants is responsible for the recent and dramatic increase in cases of autism. The preservative contains levels of ethyl mercury, which can cause brain damage. However, health officials deny that the levels present in childhood vaccines can cause autism (1).The World Health Organization performed a study which showed that autism rates in Denmark rose after the preservative was removed from vaccines and a CDC report claimed that there was no difference in cases of autism among children with varied exposure to the preservative (1). However, a recent study has shown that thimerosal affected production of a necessary enzyme (11). Use of gold salts has had some success in removal of mercury, although researchers are hesitant to test on children with autism (12).

Another theory is that childhood infections may be connected with autism in addition to other mental disorders (13). These infections affect the brain causing mental symptoms. If this theory were true, preventative treatment could be administered. Also, antibiotics have been found to be a possible treatment for autism by affecting how transcription of a possibly mutated gene (2). However, these theories remain controversial.

The cause or causes of autism remain mysterious. Although genetic components are certainly partially responsible, it remains unknown exactly what brain structures are responsible for expression of autistic behavioral traits. However, it is clear that there must be a number of genetic components to account for the wide range of possible expressions of Autistic Spectrum Disorders. Environmental factors are understood just as poorly. Even though a cure for autism may never be attained, hopefully research will lead to a better understanding of the many forms the disorder can take and therefore improve education for those with ASD as well as raise public awareness as more and more children are born with autism.

WWW Sources

1) "On Autism's Cause, It's Parents vs. Research" , New York Times

2) "Aminoglycoside antibiotics and autism: a speculative hypothesis"

3), "A question of balance: a proposal for new mouse models of autism"

4) "Autistic Spectrum Disorders: Sorting Out Autism, Asperger's Syndrome and Other Conditions"

5) "They Just Can't Help It" , Information on the male and female brains

6) "Autism"

a name="7">7) "Cells That Read Minds" , New York Times

8) "As Autistic Children Grow So Does Social Gap" , New York Times

9)A question of balance: a proposal for new mouse models of autism., PubMed Citation

10) "A question of balance: a proposal for new mouse models of autism." , PubMed abstract

11)"Mercury and autism: accelerating evidence?" PubMed abstract

12) "The Age of Autism: Gold Standards"

13) "PANDAS PITAND", Information about autism caused by infection


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