Neither question can be definitively answered by our unscientific and anecdotal inquiries. A more comprehensive study would require the efforts of epidemiologists and probably a government agency, and we will look at that prospect in future columns.
First, though, it is worth summarizing what our initial inquiries have suggested:
-- With the Amish population in the United States approaching 100,000, there should be several hundred identifiably autistic Amish.
-- We so far have located fewer than 10.
-- There no doubt could be more, but a number of people in positions to know -- doctors, health workers, an Amish-Mennonite mother of an adopted autistic child -- say they have observed the prevalence is indeed low.
-- A low prevalence could indicate the Amish have avoided some factor that is triggering autism in the rest of the population.
If autism is not nearly so common among the Amish, one or more of several factors could be at work:
-- Their isolated gene pool could be protecting them in some unrecognized way.
-- Something affecting the rest of the population is not affecting them. Candidates could include vaccines -- the Amish have a religious exemption from the mandatory U.S. immunization schedule and only a small minority vaccinates its children; environmental pollutants; something in the food chain that the Amish avoid or some wildcard factor not yet on the table.
It is well-known the Amish are isolated from modern life -- they do not drive, watch TV or use telephones, for example, but in other ways, we found, their isolation can be overstated.
They do see doctors, though not at the drop of a broad-brim hat. One of the most compelling bits of data comes from a family doctor in Lancaster County, Pa., who told us he has seen thousands of Amish for nearly a quarter-century but has never seen autism.
Like many health-conscious Americans, the Amish also use lots of nutritional supplements, we learned. In the last column we talked with Dick Warner, who is in the water-purification and natural-health business and has worked with thousands of Amish around the country. He also said he has seen no autism.
"I think a lot of it has to do with the health of the birthing mothers," Warner said. "The Amish traditionally take a lot of supplements, especially when they are pregnant."
An Amish dining table typically will have a Lazy Susan in the middle, from which everyone takes supplements, he said.
"Also, it's the kind of diet that they have," Warner added. "They don't buy store-bought meat," and it is not the center of the meal. Their farm-raised animals are not vaccinated or given growth hormones, he added. "I think there's something there -- they don't ingest the environmental toxins that are in our food chain."
Though he has seen no autism, Warner said he has observed some learning disabilities among the Amish, "but they were correctibles." In those cases, he said, the children tested high for heavy metal in their system, especially mercury. They improved dramatically through a process called chelation, he added.
Chelation uses oral medication or creams spread on the body to remove metals. Coincidentally or not, some parents of autistic children champion chelation as having improved and in some cases reversed autism -- although such results have not been scientifically validated.
"I've found that metal poisoning has a lot to do with attention-deficit problems not just amongst the Amish but amongst our own people, too," Warner said. "You've got to chelate the minerals out of them."
That converges with the view of a Virginia doctor we spoke with who said he was treating six Amish children with autism; four of the six had very high levels of mercury, he said.
The child with whom he tried chelation has improved, he said. He blamed the mercury exposure on coal-fired plants near their homes.
If anything has emerged from this excursion into the Amish world, it is how often the metals-mercury issue has arisen; two of the first three cases we identified were attributed by the Amish-Mennonite mother to vaccine reactions. A minority of doctors and parents blames a mercury preservative in vaccines called thimerosal for triggering an autism epidemic. The mainstream medical community says that has been discredited; thimerosal was phased out of U.S. childhood vaccines starting in 1999.
Warner seemed to sum up the alternative view when he said, "Mercury is a bad, bad guy."
In the next column we will post some reader comments on the Amish-autism angle. Some have found it intriguing, while others say it is irritatingly irrelevant.
This series on the roots and rise of autism aims to be interactive with readers and welcomes comment, criticism and suggestions. E-mail: firstname.lastname@example.org