New Insights Into What’s Driving the Autism Epidemic

A flurry of new research offers some intriguing clues into the mystery of what causes autism, which in the past, has been blamed on everything from childhood vaccines to poor parenting.

autism epidemic

Recently, the CDC reported that 1 in 88 eight-year-old children have autism spectrum disorder (ASD), an alarming 78 percent increase from 2002 when the number was 1 in 150. But whether the prevalence of autism is actually increasing is a subject of hot debate among experts, because it’s hard to tell how much of the increase is due to a broader definition for the disorder, improved detection methods that are leading to earlier diagnosis,or other factors still to be uncovered. One thing is certain: the more than one million children who suffer from autism and their families need help: the Autism Society states that the lifetime cost of caring for a child with autism ranges from $3.5 – $5 million.

Autism is a complicated developmental disability that usually appears by the age of three. It includes a range of brain abnormalities that affect how children communicate and interact with others, and it affects them in different ways and in varying degrees. Signs of autism may include a lack of or a delay in speech development, repetitive mannerisms, little eye contact or interaction with people, or lack of interest in play. Children do not “outgrow” autism, but early diagnosis and early intervention can lead to improved outcomes.There is no known single cause and mysteriously, the rate for boys is five times greater than for girls.

Scientists are now making major strides forward to solve the autism puzzle.

While it was previously thought that there were about 200 genes responsible, three new groundbreaking studies recently published in Nature suggest that there may be as many as 1000 high-risk autism genes responsible.

In one of the three genetic sequencing studies, researchers found that mutations known to increase the risk for autism are four times as likely to come from the father’s sperm as from the mother’s egg. They also found that the risk of passing on a genetic mutation to the child rises directly with the father’s age, a worrying finding as the average age of fathers rises. The research looked for disruptions in genetic code in a large sample of 209 families, where the child had autism and both parents did not.

“This was the first time we have been able to be definitive and point conclusively to paternal risk and age factors. A large epidemiological study from Denmark a few years ago suggested an association with paternal age. In our research, we found a clear genetic link, not just an epidemiologic link,” says Raphael Bernier, Ph.D., clinical psychologist with the University of Washington Autism Center and one of the principal investigators for the study.

In a population study published recently in the journal Pediatrics, researchers examined whether metabolic conditions during pregnancy – diabetes, hypertension and obesity, were associated with higher rates of autism. They found that obese mothers were 67 percent more likely to have a child with ASD than normal-weight mothers who did not have high blood pressure or diabetes. This is alarming, given that 34 percent of American women are obese now and current estimates project that 42 percent will be obese by the year 2030.

The study results suggest that increased insulin resistance, often seen in obese mothers, might be harming a baby’s brain development before birth. “If the mother has high blood sugar levels, that crosses the placenta and the baby has to produce it’s own insulin. As insulin is a growth promoter, and if the baby is growing faster, it needs a bigger supply of oxygen. If it doesn’t get the oxygen it needs, that can affect brain cell development,” says Paula Krakowiak, a Ph.D. Candidate in Epidemiology affiliated with the UC Davis MIND Institute and a researcher for the study.


Visit the Autism Society for more information about ASD. Nature offers a special feature about autism, called The Autism Enigma.

Originally commissioned by GE Healthy Outlook. Copyright Jane Langille.

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4 Responses to New Insights Into What’s Driving the Autism Epidemic

  1. Sharon Aschaiek November 9, 2012 at 11:43 am #

    Good to see that scientists are homing in on more specific genetic causes and correlating factors that influence the onset of autism. We need lots more research on causes to help us develop better interventions for these kids, especially since, as you note, the rate of occurrence has increased so much. But I’m glad you included information on the high cost of caring for a child with autism. We need as much, if not more, focus on supporting these families as we do on research, and it would be good to see governments, in Canada and elsewhere, more effectively meet their responsibility to these citizens and by more proactively helping these kids achieve their full potential.

    Sharon Aschaiek

  2. Kirsten November 9, 2012 at 10:30 am #

    As the mother of a child with autism, I am always interested in this stuff. When the obesity study came out it cause a great deal of outrage among autism moms, who over the years have been bombarded with alleged causes that make them feel that their child’s autism was their fault.

    The trouble with many of these studies is that they assume that correlation means causation. I can appreciate a study like this, because it does try harder to scientifically prove that the causation is there.

    Thank you for posting this. As an autism parent, I appreciate anything that raises awareness in an informed, non-sensational way.

    • Jane November 9, 2012 at 10:48 am #

      Thanks Kirsten. You’re right – any population study, like the maternal obesity study mentioned here, can never prove causation, only that a relationship has been found between two things. That relationship then needs to be researched further to determine how those things are related or if they are occurring together for other reasons, or just due to chance. The researcher was careful to state that that the relationship suggests, but doesn’t conclude, that insulin resistance in obese mothers might be acting in this fashion on unborn children, and that more studies are needed to investigate further.


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