What are the causes of autism? What factors lead to autsim? Currently, the medical community do not have an answer. However,there is a clear evidence that autism has little to do with family background and upbringing. It also has little to do with environmental factors. Again, up to now, we do not know much about the causes of autism. The only things we can be sure are: (1) Up until now, we still could not find any psychological factors causing autism. (i.e. autism is not caused by poor upbringing or parental relationship) Physiological factors are more likely to be causes of autism; (2) No single physiological factor can explain all the different autistic symptoms. This means multiple physiological factors are at work.
Folstein and Piven reported autism spectrum disorder has a 82% concordance between mono-zygotic twins and 10% concordance between dizygotic twins. Epidemiological studies also showed that the sibling recurrence at 3%. This is way higher than the prevalence of autism and showed disease clustering among certain families. Even if there are no other autistic members in the family, it is usually not hard to find that some members share similar cognitive defects, delayed language development, delayed emotional development, learning disabilities and so on. These all demonstrated autism has a strong genetic component. Further research discovered that Fragile X Syndrome, Phenylketonuria, Tuberous Sclerosis and other genetic diseases are highly related to autism. While the majority of autistic children do not have the aforementioned genetic diseases, recent research is trying to find out more genetic diseases that can cause autistic symptoms. We need to point out that in many cases, the genetic defects discovered often do not match the observed symptoms. It is suggested this can be due to defects in multiple genes and autism is general is a multi-gene disease. Nowadays new genetic research on autism is being published in an increasing pace. With the advancement of technology, we can expect the genetic mystery of autism to be gradually solved.
2. Neurological Research
Many academics tried to study autism causes from a neurological perspective. They discovered that 20% autistic children have abnormal brain
wave, 20% becomes epileptic during their adolescence and one third have high concentration of serotonin in their brains. Some autistic children
have ambiguous lateralization of brain functions. Some others have abnormal Brainstem Auditory Evoked Response (BAER). These information showed that abnormal brain function and autism is highly related. However, their precise clinical implication is not presently clear.
3. Perinatological Damage
From the survey of children born from the same parents, children suffered perinatological damage are more likely to be autistic. For example, 5% of children born from mother contracted rubella virus or influenza virus during pregnancy are autistic. Perhaps perinatological damage is not specific but the weakness it infected on the fetus might make autism more likely to occur.
4. Organic Factors
For example, brain damage, rubella infection during pregnancy, meningitis or encephalitis shortly after birth. Recent research discovered that autistic children have enlarged left temporal horn of the lateral ventricle. This implies pathological changes at the temporal lobe, possibly due to the allergic reaction of brain tissue Recent research demonstrated that some young autistic children’s immune system mistakenly identify basic brain proteins as foreign and then destroy them. This results in brain damage, possibly causes various autistic symptoms. When autistic children simultaneously have problems in mood, intelligence and social skills, they are likely related to pathological changes in the brain.
5. Environmental Causes:
In the past people think cold and over methodological way of bringing up a child such that the child lacks sufficient stimulus and social behavior eduction is a major cause of autism. They think children growing up in a monotonic environment are more likely to repeat certain action for self-stimulus and as a result become indifferent to the outside environment. Autistic children often have parents who are highly skilled professionals that received high level of education, relatively smart but have obsessive compulsive tendency, treat children coldly and inflexibly such that children often could not feel the family warmth. Nonetheless, such parental cause is now discredited Research showed that the main cause is pathological change in the brain. This could be due to virus infection or metabolic disorder but so far no definite cause is confirmed.
6. Other diseases:
Some diseases exhibit autistic symptoms, for example, Rett’s Syndrome, Fragile X Syndrome and so on. All in all, since the cause of autism remains unknown, it is possible that it can be further classified into diseases with more precise causes but this all depends on the further exploration of medical research.