New Autism Studies Question Emphasis on Genetic Causes
After autism was first identified in 1943 by child psychiatrist Leo Kanner, it was widely believed — in large part due to the work of self-styled child development expert Bruno Bettelheim — that autism was caused by bad parenting and specifically by emotional frigid “refrigerator mothers” who failed to bond with their children, who sunk into an “autistic withdrawal.” Since the 1970s, there has been an emphasis on finding a genetic basis for autism, with some studies saying that 90% of cases of autism can be attributed to genetics, notes the†New York Times.
Two new studied published in the Archives of General Psychiatry suggest that more attention needs to be focused on possible environmental factors for autism. It should be noted that by “environmental factors,” both studies do not refer specifically to, for instance, pesticides, air pollution or “environmental toxins,” but factors such as parental age, low birth weight, multiple births, and maternal infections during pregnancy (in one study) and exposure to medications taken during pregnancy (in the other study) — that is, to other factors not in a young child’s genetic make-up that can affect his or her health.
One study analyzed data about 192 pairs of identical and fraternal twins in which at least one twin has the neurodevelopmental disorder. Identical twins share 100 percent of their genes and fraternal twins, 50 percent. Using data was drawn from records from the California Department of Developmental Services, scientists found that, for boys, autism occurred in 77 percent of the identical twin pairs and 31 percent of the fraternal twin pairs; for girls, in 50 percent of the identical twin pairs and 36 percent of the fraternal twins pairs.
These figures are “in line” with other recent studies, as the Los Angeles Times says. The researchers then put these figures into a computer model that used statistical modeling which took into account genetic factors, environmental factors shared by both twins and environmental factors not shared by both twins. From this, the researchers found that genetics accounted for 38% of the cases could be caused by genetic factors and 58 percent by the environment the twins shared.
The second study looks at the use of anti-depressant medications during pregnancy by examining the medical records of 298 children diagnosed with autism spectrum disorders in the Kaiser Permanente Medical Care Program in Northern California. 6.7 percent of the children’s mothers had taken selective serotonin reuptake inhibitors, or SSRIs, while pregnant. For a control group of 1507 randomly selected children, 3.3 percent were found to have taken SSRIs. From these findings, the researchers concluded that “exposure, especially during the first trimester [to SSRIs], may modestly increase the risk” of a child developing an autism spectrum disorder. As the Los Angeles Times notes, some scientists point out that “it is possible that the depressed mothers may have had some underlying biological condition that both caused their depression and made their children more likely to develop autism.”
The†Los Angeles Times asks if, based on the findings from the first study, “the influence of genetic factors on the susceptibility to develop autism, overestimated.” Indeed,†study leader Dr. Joachim Hallmayer, an expert on autism genetics at†Stanford University, says that “It took me a bit by surprise that the heritability of autism was so much lower than previous studies calculated.” Another†senior author of the study, Neil Risch, a geneticist and epidemiologist at the University of California, San Francisco, says “We, like everyone else, were very surprised because we didnít expect it to be that high,” in the†New York Times.
But a behavioral geneticist not involved in the study,†Robert Plomin of King’s College London, comments “Their data is so similar to everybody else’s, and yet they come up with another conclusion. I don’t know how this happened.”
Clara Lajonchere, vice president of clinical programs for the US-based autism organization Autism Speaks, says that the two studies call for renewed attention in “looking at prenatal and perinatal factors with respect to autism susceptibility.” There have been a number of studies looking at whether various factors in expecting mothers’ health (having the flu, taking†prenatal vitamins, alcohol consumption, to name a few) might play a role in a child becoming autistic.
One thing I hope that scientists keep in mind as they pursue such avenues of research is that the line is very thing between pointing out what women did or did not do during pregnancy, and the long-discredited phenomenon of “mother blaming” as a cause for autism. I’ve met more than a few women of autistic children who have long questioned what they should or shouldn’t have done, from not having a child vaccinated, to eating different foods during pregnancy, to many other factors. The era of pointing the finger at mothers specifically and parents in general for “making” their child autistic is not so far away from us. We need to keep this in mind as we try to figure out ways to ensure the best health and outcomes possible for mothers and their children and, perhaps most of all, for children who are autistic, for whatever reasons or causes.
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