There is a very interesting “Opinion” piece in the New York Times today: Immune Disorders and Autism – NYTimes.com. By Moises Velasquez-Manoff is details some recent work that the author believes relates to autism and a variety of other human ailments with an autoimmune connection.
The general logic/key points seem to be as follows:
- Some autism cases look like a form of inflammatory diseases with the immune system overactive (inflammation on high, anti-inflammation on low, or some combination thereof)
- Infection of a mother during pregnancy increases the risk of having a child with autism.
- In animal models, inducing inflammation in the mother (even without an infection) leads to an increased risk of behavioral “problems” in her offspring
- Inflammatory and/or autoimmune diseases (e.g., asthma) have increased in incidence along with autism.
- If a mother has automimmune or inflammatory diseases such as rheumatoid arthritis celiac disease she has a higher risk of having a child with autism. Similarly if a mother has allergies or asthma during the second trimester, there is a higher risk of having children with autism.
- Many automimmune and inflammatory disorders and autism are all more prevalent is the developed world.
- The developed world is generally cleaner that the developing world.
- There are many fewer parasites in people in the developed world.
- Parasites are known to suppress inflammation.
- Therefore, we may be able to stop/limit autism, asthma, and other inflammatory diseases by purposefully infecting people with parasites from our evolutionary past.
Now, personally, I like the general hypothesis here. It makes complete sense. But alas, it is suffers from this issue that is spreading almost as fast as these diseases – a lack of a discussion of the distinction between correlation and causation. I have been obsessing about this a bit recently with studies of the microbiome. Overall, I do like this current article. It mixes human epidemiological studies with controlled animal studies with discussion of conceptual models. But alas there is really no discussion of the challenges if disentangling correlations vs. causation. And I think it is a bit dangerous in the latter parts with the jump to potentially curing these various ailments by purposeful infection with parasites. Again, I like the idea. But a few caveats would have been nice. I am glad it was marked as an opinion piece but even when one states an opinion about a medical issue, one can still say “there are reasons why this might not be true .. such as …”. Too bad that wasn’t done here.
UPDATE – Emily Willingham has written a VERY detailed critique of the article that I think everyone interested in anything related to this topic should read: Emily Willingham: Autism, immunity, inflammation, and the New York Timeswww.emilywillinghamphd.com.