Dr. Irva Hertz-Picciotto is an epidemiologist at the University of California at Davis MIND Institute studying autism and is on the board of Autism Speaks. She recently wrote a blog about a series on autism by the LA Times, pointing out errors in the LA Times article. I’m sure she would appreciate someone writing a response to her blog.
The LA Times article said that genetic diseases like autism don’t increase rapidly (unless people afflicted breed very rapidly), so there cannot be an epidemic of autism. All the afflicted children, thousands of treatment centers, and billions in research dollars are all an illusion. The article went on to use Fragile X Syndrome as an example of a genetic cause of autism.
In fact, about 1/3 of children with fragile genes have autistic symptoms and 2/3 do not. In the third that have autistic symptoms, few have the core autistic symptom of lack of emotional reciprocity. That is, they bond with mom, but they are extremely anxious with others. However, what bothers me is the assumption that a genetic association means causation. With genetics, unlike the rest of science, a genetic association, even one in which two-thirds of the afflicted children are free of autistic symptoms, means causation. In fact, what scientists actually know is that Fragile X genes and atypical autistic-like symptoms are associated one-third of the time. That is what they know, no more.
Dr. Irva Hertz-Picciotto correctly took the LA Times to task for listening only to genetic old-timers and their circular logic. Dr. Hertz-Picciotto correctly pointed out that recent genetic studies indicate a strong environmental component for autism. She then wrote that very recent studies show lack of prenatal vitamins (contain vitamin D), short time between pregnancies (exhausts vitamin D supply of mother), air pollution (blocks vitamin D-engendering UVB light), and season-of-birth (late winter with increased risk) differences all point to an environmental factor. She could have added that a recent study found that exclusive breast-feeding (breast milk contains virtually no vitamin D for most 21st century women) and lack of participation with WIC perinatal nutrition programs (WIC programs include vitamin D for both mom and infant) was associated with autism.
I wish Dr. Hertz-Picciotto would look again at the state by state autism rates and compare it to reports of state by state ground based UVB monitoring stations (actually, it caught my eye and has already been submitted for publication). You see, I am afraid of riding Occam’s razor (which states “simpler explanations are, other things being equal, generally better than more complex ones”), so I try to keep it simple.
There it was, right before her nose, six facts that one cause can explain: vitamin D deficiency. Sure, my dog can come up with six different theories for the six facts, no prize for that. The trick is to assign as many things as possible to the same cause, and then you may find the truth. To quote Sir Isaac Newton,
“We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes.”