by James Hubbard, M.D., M.P.H.
This new study, relating autism to increased precipitation, is a classic “scare of the day” news story. You will see it everywhere. Some people will latch onto it as a factual cause of autism, but you will never hear if it is disproven. Don’t get me wrong. The researchers should publish it. It is interesting, but it is a starting point and nothing more.
We know little about causes or risk factors for autism. So you have to start somewhere looking for clues. The researchers started with a hypothesis that there could be some environmental trigger. They scoured state records in Washington, Oregon and northern California, looking for autistic children 6 to 12 years old. Then they looked at where the child was living and how much precipitation that area got when the child was under age 3. They found that more autistic children grew up on the rainy side of the states. (In case you didn’t know, it rains a lot on the coastal side of these areas, but much less east of the mountain range in the middle.)
But what does that really mean? Rain causes autism? Nature is against us? A few years back researchers found that more men with prostate cancer had undergone a vasectomy. Later studies found it was just a coincidence. So why do cross-sectional studies like this in the first place?