In fact, those women who suffered the most physical and emotional abuse were 60 percent more likely to have a child with autism than women who were not abused.
The most severe combination of physical, emotional and sexual abuse meant a woman was 3.5 times more likely to have an autistic child than a woman who hadn’t been abused, said lead study author Andrea L. Roberts, Ph.D., research associate in the department of social and behavioral sciences at the Harvard School of Public Health.
For the study, researchers looked at data from more than 52,000 women enrolled in the Nurses’ Health Study II, a large study of women’s health beginning in 1989. Of the women in the study, 451 had a child with autism.
To determine if they had suffered from childhood abuse, the participants were asked if they’d ever been hit hard enough to be bruised, or been struck by a belt or other object, and if they had been subjected to cruel punishments, insulting comments or screaming.
Researchers also asked the women if they had ever experienced unwanted sexual touching or forced sexual contact by an adult or older child.
The researchers also looked into whether pregnancy-related risk factors, which have been associated with autism, further raised the risk for the condition. These risk factors include gestational diabetes, preeclampsia and premature birth. Other risks, such as smoking, use of selective serotonin uptake inhibitors (antidepressants) and abuse by an intimate partner during pregnancy were also included in the study.
The findings revealed that although the abused women experienced more pregnancy-related risk factors, these factors were only a small part of the link between child abuse and autism risk.
The researchers note that the study shows an association, not a cause-and-effect link, and it’s not clear how childhood abuse may contribute to autism.
But there are valid reasons for the association. One theory is that abused women may have a heightened response to stress. This may lead to inflammation or high levels of stress hormones, which affect the fetal brain.
Another possible explanation is that parents who abuse children may be mentally ill, which may raise the risk for other mental disabilities, including autism, in relatives, Roberts said.
One expert worried the findings may fuel parents’ fears that they caused their child’s condition.
“What is concerning is the potential effect this could have on mothers,” said Tanya Paparella, Ph.D., director of the Early Childhood Partial Hospitalization Program at the University of California, Los Angeles, which treats young children who have autism.
“We know that autism is strongly genetic in its origin, but we know very little about where the genetic risk factors lie and where the environmental risk factors lie, and very little about the combination of genetic and environmental risks,” said Paparella, who was not involved in the research study.
Still, the study adds a new piece to the autism puzzle. “We are struggling a little with trying to find out what causes autism,” Roberts said. “Our study points to a possible new direction in the research.”
The fact that pregnancy-related risk factors for autism were higher in women who were abused “suggests that the effect of abuse can reach across generations,” Roberts added. “As a society, we need to focus more on how children are cared for and give more support to families who might be at risk for abusing their children.”
Source: JAMA Psychiatry