Sophisticated imaging techniques are beginning to reveal some of the differences in brain function between autistic and normal individuals. So it is not true that there are no physical differences; we just haven't had the imaging capability previously to see them.
Even given that we may not have a complete understanding of what exactly is happening, we can still look at correlations. And there is no doubt that the rise in autism correlates with increased HFCS consumption.
There is no correlation that I know of, nor any mechanism to explain why fructose from corn would cause brain damage, but identical fructose from fruit, honey, agave, etc., would be perfectly harmless. The author of this study is, as other posters have pointed out, a kook.
Correlation is not causation. That seems to be a very difficult concept to grasp, but it is essential to understand it.
I see these things as tantalizing hints until we have more concrete answers. And one of the fudging factors introduced by epigenetics is that the answer for what YOU should eat might be very different from what I should eat!
Epigenetics, I'm afraid, is going to be one of those catch-alls that people start throwing around, thinking they know what they are talking about. I've seen similar woo expressed by people talking about DNA.
(Technical discussion follows.) Specifically, epigenetics refers to modification of DNA that does not actually change its structure. Most often, the modification consists of methyl groups being attached at specific nucleotide sequences. These methyl groups have the effect of changing gene expression. The accumulation of such modifications takes place over a period of time. Identical twins have nearly identical epigenomes at 7 years old, but not at 67 years old. My hypothesis, aka "educated guess": If autism can be traced to alterations in the epigenome, those alterations are highly unlikely to have happened within the child's short life (autism symptoms can start appearing in 12 mo old children). They'll be changes that occurred at the level of the gametes produced by the mother or father.
I am not sure you can equate fructose in it’s natural form (in fruit!) to HFCS.
Naturally occurring fructose is almost always complemented by a good mix of some of the 20 or so other sugar forms. (ribose, xylose, mannitol, etc).
You make a good point about epigenetics being a “later” process. But if it does turn out to be epigenetic-related, we are looking at the newborns immediate environment, which points to the womb and possible habits/lifestyle choices of the mother.
Whatever it is, it is interesting, and I’m not smart enough to say for sure one way or the other.
I try to keep an open mind about things, that’s all.
BTW, methylation is the primary method of turning on genes for gene expression, but there are about three other variants of the same idea.