Could Autism be More Related to Environment than We Thought?

Your child’s mental health may be more linked to his environmental wellness than previously thought, according to researchers at Stanford University. Their new study in twins, published in July’s Archives of General Psychiatry, found that environmental factors may play a larger role than shared genes in the development of autism, while a second study in the same journal discovered that one potentially important environmental trigger is taking anti-depressants during pregnancy.


For the first study, 192 pairs of twins from a state-wide California registry of children were identified as receiving services for developmental disabilities. The researchers examined and tested each child to confirm that at least one twin was diagnosed with an autism spectrum disorder. Of the twin pairings, 54 were identical (sharing all of the same genes) and 138 were fraternal (meaning they only shared half of their genes). Lead study author Dr. Joachim Hallmayer, an associate professor of psychiatry and behavioural science at Stanford University, said it’s not surprising that the identical twins were more likely to each have autism, since they share all the same genes, but if autism was 100% due to genetics then both siblings in each pair of identical twins would have it.


The researchers explained that the twins’ shared environment, be it in utero or in early life, has to play a major role in their wellbeing in this way. The researchers calculated that genes account for 37% of the risk of “classic” or severe autism and 38% of the risk of milder autism spectrum disorders. This means that environmental factors form 55% of your child’s autism risk and 58% of his risk for an autism spectrum disorder. Hallmayer admitted, ‘I was very surprised. The environmental influence is stronger than I thought. It doesn’t mean that genes don’t play a role, but they may not play as big a role as thought.’


Dr. Gary Goldstein, president and CEO of the Kennedy Krieger Institute in Baltimore, pointed out that the results of the study confirm how important it is for researchers to investigate autism’s environmental triggers. He commented, ‘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. This study gives further support that we should be looking at both genes and the environment.’


A second study, this time carried out by researchers from Kaiser Permanente Medical Care Programme in Northern California, found that if you take antidepressants known as selective serotonin reuptake inhibitors (SSRI) during pregnancy, your child risk of autism increases two-fold. Moreover, if you take these drugs during the early stages of your pregnancy, your child’s autism risk is three times higher than the children of mothers who don’t use the antidepressants at all.


However, Dr. Natalie Meirowitz, chief of the division of maternal foetal medicine at Long Island Jewish Medical Centre, advises against flushing your medications if you suffer with depression, even if you’re expecting. She explained that your wellness, and your baby’s, is at risk to the depression itself, as depressed women may self-medicate with drugs and alcohol, have a poor diet, fail to keep their prenatal appointments, and be unable to care for their baby after delivery. According to Meirowitz, ‘Pregnancy is a very emotional time for women, and we know that a woman who stops her medication needs a lot of support. 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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