Autism linked to mom's weight, diabetes
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Do women who are overweight or diabetic have a greater chance of giving birth to children with autism?
That is the implication of a study being published in the journal Pediatrics today by researchers at the MIND Institute of the University of California at Davis. The study found that women who were obese or had diabetes had greater odds of having children with autism and children with developmental delays.
"There already was a lot of [scientific] literature on the connection between mothers with diabetes and cognitive impairment in kids," said senior author Irva Hertz-Picciotto, and since many autistic children also have retardation, "that was part of our motivation for thinking this might be a plausible hypothesis on autistic spectrum disorder."
The study "suggests there is something more global going on" between mothers' health and brain development in the womb.
An autism genetics researcher at the University of Pittsburgh, however, said she doesn't believe the study backs up its conclusions.
Kathryn McFadden, a pathology professor at Pitt, said the study actually shows no strong link between mothers who had diabetes and children with autism.
"Mothers with diabetes were 2.3 times more likely to have a child with developmental disability," the study said, "but the association between diabetes and autism spectrum disorder did not reach statistical significance."
Specifically, among children with autism, 9.3 percent had diabetic mothers, while among typically developed children, 6.4 percent had diabetic mothers, a difference that was not very significant, Dr. McFadden said.
Still, another researcher, Michael Georgieff of the University of Minnesota, said the UC Davis study "is an important paper because it emphasizes the role of the prenatal environment on the developing brain."
Dr. Georgieff, a pediatrics professor, has done research showing that diabetes can cause iron and oxygen deficiencies that hurt development of the fetal brain.
"For example," he said in an email, "in the case of diabetes in pregnancy, lack of iron and lack of oxygen to the fetus during the later parts of the pregnancy negatively affects the developing hippocampus, the area of the brain that mediates memory processing. Our work in both humans and in [animal] models demonstrates significant learning and memory deficits and structural alterations to the hippocampus after late gestation iron deficiency."
However, Dr. Georgieff also noted that the California study's link between diabetes and autism wasn't as strong as the correlation with other development problems.
The link between maternal health and autism "is a little tougher to pinpoint," he said, because the exact brain problems and source of autism "remain unknown."
Ms. Hertz-Picciotto, who has a Ph.D. in epidemiology, said that her group did find a significant correlation between obesity and both autism and developmental delays, and the study noted that being overweight "is a significant risk factor for both [high blood pressure] and diabetes and is characterized by increased insulin resistance and chronic inflammation."
"We also know that the orchestration of embryological development is amazing, because everything has to happen at just the right time, and the fetus can be exquisitely sensitive to even transient losses of energy supply" like the kind that may happen in diabetes, she said.
Autism is a brain disorder characterized by poor social communication skills and repetitive interests or behaviors.
Dr. McFadden said part of the disagreement over studies like this one is because autism researchers increasingly tend to fall in one of two camps -- those who believe most of the cause is genetic, and those who "are alarmed at the rising incidence of autism and are hunting for environmental causes."
She acknowledged she is biased toward genetic explanations, but noted that the MIND Institute, which stands for Medical Investigation of Neurodevelopmental Disorders, was established partly to find possible environmental causes of the disorder.
There is one area where Dr. McFadden and Ms. Hertz-Picciotto shared common ground.
"If this study would cause people to think about what they eat and go after the food industry [on nutrients], that would be great," Dr. McFadden said.
"There is a long history of blaming parents for autism, and we don't want this to be misinterpreted as blaming the parents," Ms. Hertz-Picciotto said, "but we did this study because we're interested in modifiable factors to see if we can get the autism rates to go down.
"We already know that modifying lifestyle habits and diet are going to be beneficial to the mom, and now we have some reason to believe it will be of benefit to your children."
First Published April 9, 2012 3:15 pm