Better clues to the causes of the autism phenomenon come from parallel “epidemics.” The prevalence of inflammatory diseases in general has increased significantly in the past 60 years. As a group, they include asthma, now estimated to affect 1 in 10 children — at least double the prevalence of 1980 — and autoimmune disorders, which afflict 1 in 20.
Both are linked to autism, especially in the mother.
Here’s where it gets really interesting:
Yet when you consider that, as a whole, diseases of immune dysregulation have increased in the past 60 years — and that these disorders are linked to autism — the question seems a little moot. The better question is: Why are we so prone to inflammatory disorders? What has happened to the modern immune system?
There’s a good evolutionary answer to that query, it turns out. Scientists have repeatedly observed that people living in environments that resemble our evolutionary past, full of microbes and parasites, don’t suffer from inflammatory diseases as frequently as we do.
Generally speaking, autism also follows this pattern. It seems to be less prevalent in the developing world. Usually, epidemiologists fault lack of diagnosis for the apparent absence. A dearth of expertise in the disorder, the argument goes, gives a false impression of scarcity. Yet at least one Western doctor who specializes in autism has explicitly noted that, in a Cambodian population rife with parasites and acute infections, autism was nearly nonexistent.
For autoimmune and allergic diseases linked to autism, meanwhile, the evidence is compelling. In environments that resemble the world of yore, the immune system is much less prone to diseases of dysregulation.
In other words, the hygienic world we have created in the West is an evolutionary anomaly, and our bodies may not have kept up with it.
This is interesting to me because both my wife and I have autoimmune issues. Julie has always had significant allergies and asthma, and arthritis runs in her family. I have Raynaud’s syndrome, which has really ramped up in the past few months, and which, I think, is linked to the chronic fatigue episodes that have dogged me. Our oldest son is on the very mild end of the autism spectrum, and has all kinds of autoimmune issues. Hmm.
I wonder too if there are other environmental factors playing off our immune systems that lead to autism. One of my son’s doctors back in Dallas was convinced that autism is a condition of the industrialized world, and that one day we would discover a link between our environment and autism. Moises Velasquez-Manoff proposed just such a link, though not the link one would suspect. Could this be the whole story, or just a significant part of it? What do you think?