I first heard this idea from Caroline Rodgers, a science writer, and have blogged about it several times . Nevertheless, the website’s home page taught me several things I didn’t know:
1. “A recent major study of twins supports earlier studies in concluding that environmental exposures during or shortly after gestation cause a majority of autism cases.” This is inconsistent with many other explanations (e.g., vaccine, genetic).
2. “In a recent study, autistic children had reduced connectivity between the two sides of the brain.” Which supports the idea that neural misdevelopment is a cause of autism.
3. “Twenty years ago, the FDA increased the allowable intensity of prenatal ultrasound 8-fold to improve images. Autism rates have risen dramatically since that time.”
4. There is “widespread misunderstanding among ultrasound operators of the safety guidelines.”
5. “A fast-growing commercial business is keepsake ultrasound photos. Franchisers advertise that no medical background or certification is required.”
I asked Hirasaki a few questions.
How did you become interested in this?
My age and my profession led me to the theory that the rise in autism is caused by exposure to prenatal/neonatal ultrasound.
Who else, in addition to Caroline Rodgers, has independently had this idea and written or posted about it?
Manuel Casanova, a neurologist. Nancy Evans, a science writer.
When you started looking into possible causes of autism, did you look into other possible explanations?
No. I asked myself what had changed about having a baby. Ultrasound seemed to be the obvious major change. Exposure to caffeine, smoking, alcohol and medications had all decreased.
Was there any particular evidence that you found especially persuasive?
On my website, there are 37 papers pertinent to the topic. My primary theory is that overexposure is the cause. The most persuasive evidence that points to this is:
What has made it difficult for the research community to find this?
I would add that links between sonograms and left-handedness are more evidence that sonograms can cause important brain changes. Here is a doctor who does sonograms dismissing the connection but what I find important is that the connection has been found repeatedly.