Understanding Risk Factors and Causes
We do not know all of the causes of ASDs. However, we have learned that there are likely many causes for multiple types of ASDs. There may be many different factors that make a child more likely to have an ASD, including environmental, biologic and genetic factors.
What Research Tells Us
- Most scientists agree that genes are one of the risk factors that can make a person more likely to develop an ASD. Studies have shown that:
- Among identical twins, if one child has an ASD, then the other will be affected about 60-96% of the time.
- In non-identical twins, if one child has an ASD, then the other is affected about 0-24% of the time.
- Parents who have a child with an ASD have a 2%–8% chance of having a second child who is also affected.
- ASDs tend to occur more often in people who have certain other medical conditions. About 10% of children with an ASD have an identifiable genetic, neurologic, or metabolic disorder, such as:
- Fragile X syndrome
- Tuberous sclerosis
- Down syndrome
- Other chromosomal disorders
- Some harmful drugs taken during pregnancy also have been linked with a higher risk of ASDs, for example, the prescription drugs thalidomide and valproic acid.
- We know that the once common belief that poor parenting practices cause ASDs is not true.
- There is some evidence that the critical period for developing ASDs occurs before birth. However, concerns about vaccines and infections have led researchers to consider risk factors before and after birth.
So there you have it - the CDC has quietly shifted its position and seems ready to look into the biological and environmental side of autism.
Its about damn time.
Its about damn time.
Good post. It is about time too. Long past time.
ReplyDeleteThanks.
ReplyDeleteI have to wonder how much of the CDC's change in position is attributable to the 50% increase in prevalence in 4 years and how much is attributable to the change in administrations.
I would like to think that this sort of thing is beyond politics but I know that isn't the case.
It surprises me that premature birth and its associated neurological damage (intraventricular hemorrhage, a certain form of brain bleed which may lead to hydrocephalus), was not listed. Research has found that up to 25% of preemies display autistic tendencies on a screening test at age 2 (this doesn't mean all are autistic, quite likely most will not actually turn out to meet diagnositc criteria, but it still indicates a major risk factor).
ReplyDeleteI believe that there are a number of risk factors that were not mentioned. For example, if the mother has rubella during the pregnancy or if the mother has an autoimmune disorder, such as celiac, there is an increased risk of autism.
ReplyDeleteI think the important point is that the CDC is talking about non-genetic causes at all - this is a welcome shift from their previous positions.