Environment may play bigger role in autism development

A new twin study as reported in Health News suggests that the environment may play a bigger role than shared genes in autism development and that taking anti depressant drugs may add to that factor.

During one study, which included 52 pairs of identical twins and 138 pairs of fraternal twins, researchers from Stanford University identified that about 42.5 percent of the male-male pairs and 43 percent of the female-female pairs of identical twins both had autism. About 12.9 percent of the male-male fraternal twins and 20 percent of the female-female fraternal twins both had autism.

Dr. Joachim Hallmayer, an associate professor of psychiatry and behavioral science at Stanford University, explained that the identical twins were more likely to each have autism, since they share all the same genes, but considering that not every sibling in each pair of twins does not have autism, the disorder can not be 100% genetic.

“I was very surprised. The environmental influence is stronger than I thought,” Hallmayer said. “It doesn’t mean that genes don’t play a role, but they may not play as big a role as thought.”

“I think everyone in the field believes that genetics are important to autism and that the environment must also be involved. But we don’t know exactly what those environmental factors are, and how those factors interact with the genes,” said Dr. Gary Goldstein, president and CEO of the Kennedy Krieger Institute in Baltimore. “This study gives further support that we should be looking at both genes and the environment.”

Research has suggested that a list of possible factors, including advanced maternal or paternal age, assisted reproductive technology and artificial insemination, maternal infections during pregnancy, giving birth to multiples, prematurity and low birth weight and complications during birth, could be among the environmental factors.

Another possible environmental factor is the use of certain medications during pregnancy, including antidepressants.

Researchers also found in a separate study, a risk of autism spectrum disorder among children whose mothers took antidepressants, such as Celexa, Paxil, Prozac and Zoloft, during pregnancy, and that the risk was more than three times higher if the mothers took the drugs during early pregnancy, compared to children without the disorder.

Kaiser Permanente Medical Care Program in Northern California’s research team cautioned that the number of children in the study who were exposed prenatally to antidepressant drugs were low. They say that further studies are needed to authenticate the results.

Though there are risks and benefits in taking any medication during pregnancy, Dr. Natalie Meirowitz, chief of the division of maternal fetal medicine at Long Island Jewish Medical Center in New Hyde Park, cautioned expectant mothers who suffer from depression not to get rid of their medications.

Because depression itself poses a risk to mother and baby, depressed women may instead self-medicate with drugs and alcohol, fail to eat right and keep their prenatal appointments, and be unable to care for their baby after delivery, Meirowitz said.

“Pregnancy is a very emotional time for women, and we know that a woman who stops her medication needs a lot of support,” she said. “The decision to stop medications has to be made very carefully with the patients’ psychiatrist, obstetrician and with their significant other. It shouldn’t be made lightly.”

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