Lilly, on 09 April 2012 - 02:02 PM, said:
BTW, thin women can and indeed do give birth to autistic children. Being overweight somehow increases the risk factor...and they don't as of yet know how/why this is the case. It very well could be there's something happening that leads to both obesity and autism. In other words, obesity might not be causing the autism, but rather something else is causing both the obesity and the autism. We should be very careful in drawing any conclusions regarding cause based on these findings.
We know autism spectrum disorders are highly heritable, but there is a large environmental component as well. This component probably comes by way of state modifications (such as methylation) to DNA--in other words; epigenetics.
Its strange, just about a month ago I was thinking how little research had been done on incidence of maternal obesity and autism spectrum. Its well known that maternal obesity alters lots of things in the fetus, mostly in two ways. By way of advanced glycoslyation end products and by way of hormones that cross the placenta and act on cytoplasmic steroid receptors which alters DNA expression (like insulin for instance).
The problem with this I see is though, there really isn't evidence to show that autism incidence is actually increasing, but rather an artifact of changing DSM diagnostic indicators. The problem is there isn't an objective test for autism, its a clinical diagnosis. So over time variance in clinicians will alter the rate it is diagnosed. Interestingly, when we look at retrospective cohorts the incidence of autism spectrum remains the same in current age groups as older ones. Also interestingly, when you look at the "increase" in autism diagnoses over time you see a decrease in other similar diagnoses.
I agree that we should be careful about drawing any hard and fast conclusions based on this (especially considering I haven't read the actual research yet

), but to me it seems to further support that environment by way of epigenetics and heritability are cause of autism spectrum disorders.