Mother’s abuse in childhood may confer autism risk in offspring
A mother’s exposure to childhood abuse was associated with an increased risk for autism in her child, according to new data.
“Before and during pregnancy, women exposed to childhood abuse are more likely than those unexposed to experience circumstances and engage in behaviors that may be detrimental to the fetus, including smoking, drug use, overweight, stress, and immediate partner violence victimization ...” the researchers wrote. “Therefore, maternal exposure to childhood abuse may be a risk factor for autism in offspring.”
Andrea L. Roberts, PhD, of the Harvard School of Public Health, and colleagues examined data from the Nurses’ Health Study, II, a population-based cohort of female nurses, of whom 54,963 reported on whether they had ever had a child with an autism spectrum disorder (ASD) and also had provided information about maternal childhood abuse. A control group of 52,498 mothers of children without autism were randomly selected for comparison.
Andrea L. Roberts
According to the researchers, 3.4% of women in the study were exposed to serious sexual abuse.
The most severe forms of childhood abuse were associated with the greatest prevalence of ASD compared with no abuse (1.8% vs. 0.7%; P=.005). Adjusting for demographic characteristics, the greatest relative risk for autism was 3.7 (95% CI, 2.3-5.8).
With the exception of low birth weight, all adverse perinatal conditions were more prevalent among women who were abused as children. The researchers adjusted for these conditions and found that the relationship between childhood abuse and autism risk in offspring was only slightly attenuated (RR=3.0 for the most severe abuse; 95% CI, 1.9-4.8).
Roberts and colleagues proposed a number of reasons for the relationship between maternal childhood abuse and autism risk in offspring. Adverse conditions as a result of childhood abuse, including poor diet, substance use and infection, may account for the association. Trauma from abuse also can affect the mother’s biological system, specifically the hypothalamic-pituitary-adrenal axis, the hypothalamic-pituitary-gonadal axis and the immune system, conferring autism risk to her children. Another explanation may be that hyperactivity to stressors can negatively affect the fetus.
Finally, exposure to childhood abuse may be indicative of genetic risk for autism that is carried over to the offspring. Based on previous study results, Roberts and colleagues suggested that genetic risk for an ASD may be shared alongside genetic risk for other mental disorders, of which physical and emotional abuse is a manifestation.
“If maternal childhood abuse is associated with autism in offspring primarily through shared genetics, mental disorders that specifically increase the risk for child abuse perpetration may overlap genetically with those that increase risk for autism in children,” the researchers wrote.
Roberts told Psychiatric Annals that the findings mostly suggest new avenues for research.
“However, we did find that women who experienced childhood abuse, especially severe abuse, were more likely to have almost every pregnancy-related health risk factor we examined (8 of 9),” she said. “It may be beneficial for clinicians working with pregnant women to assess childhood abuse exposure to better understand the challenges faced by these patients. It is possible that addressing stressors in their lives and helping them handle stress better may ameliorate these risks.”
Disclosure: The researchers report no relevant financial disclosures.