Autism appears to result from developmental factors that affect many or all functional brain systems. Neuroanatomical studies and the associations with teratogens (agents responsible for malfunctions) strongly suggest that autism's mechanism includes alteration of brain development soon after conception. Brain weight and volume and head circumference tend to be greater in autistic children. The cellular and molecular bases of pathological early overgrowth are not known, nor is it known whether the overgrown neural systems cause autism's characteristic signs.

Current hypotheses include: -An excess of neurons that causes local overconnectivity in key brain regions.

-Disturbed neuronal migration during early gestation. -Unbalanced excitatory-inhibitory networks. -Abnormal formation of synaspes and dendritic spines.
Interactions between the immune system and the nervous system begin early -during embryogenesis, and successful neurodevelopment depends on a balanced immune response. Several symptoms consistent with a poorly regulated immune response have been reported in autistic children. It is possible that aberrant immune activity during critical periods of neurodevelopment is part of the mechanism of some forms of autism. Several neurotransmitter abnormalities have been detected in autism, notably increased blood levels of serotonin (serotonin is believed to play an important role as a neurotransmitter, in the inhibition of anger, aggression, body temperature, mood, sleep, vomiting, sexuality and appetite), but whether these lead to structural or behavioral abnormalities is unclear. Also, some inborn errors of metabolism are associated with autism but probably account for less than 5% of cases.
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Here is what John said today:
Today i asked mother why I am special and others are not. She told me that this is because I have a very special brain that only a few others have. I know this. The brain is the control centre for all the activities of the body, dealing with intelligence, memory, learning, sight and visual reflexes. I am able to recite all the countries in the world and their capitals as well as every prime number up to 7057. Clearly, this shows that I am intelligent.
However, there are somethings I do not like that others cannot understand. Is this also because I am special? I asked Mother this, but she could not reply.
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Truly, autistic people are different from us, but this does not give us a reason to hate them or alienate them. They are still human beings, albeit slightly different.

Si Chun