The new study investigates why stress during pregnancy is implicated in autism development.
The new study, led by Dr. David Beversdorf of the University of Missouri (MU) in Columbia, is published in the journal Autism Research.
Autism spectrum disorder (ASD) includes many conditions that were previously diagnosed separately. These include autistic disorder, pervasive developmental disorder not otherwise specified, and Asperger syndrome.
ASD is a developmental disability that causes social, communication, and behavioral challenges; individuals with ASD have learning, thinking, and problem-solving abilities that range from gifted to challenged.
In the United States, about 1 in 68 children have been diagnosed with ASD, according to the Centers for Disease Control and Prevention (CDC).
Although it occurs in all racial, ethnic, and socioeconomic groups, ASD is about 4.5 times more common in boys than girls.
Dr. Beversdorf explains that although autism was previously seen as a genetic disorder, recent research has implicated environmental influences - including stress - in the development of the condition.
"We know that some mothers who experience significant levels of stress don't have children with autism, but others do," he says. "To help understand why, we studied a gene that is known to affect stress and found a link between it and the development of autism with exposure to stress."
Findings are significant, but more research is needed
To conduct their study, the researchers looked at two groups of mothers of children with ASD: a group of families at MU and a group of families at Queens University in Ontario, Canada, where researchers collaborated with the MU team.
The investigators surveyed the mothers about stress during their pregnancy, including loss of a job, divorce, or moving. They then tested their blood for a variation of the stress-sensitive gene called 5-HTTLPR.
This gene regulates serotonin in the nervous system, but when a variation of the gene exists, it increases the body's reaction to stress, say the researchers.
Results show that both groups of mothers with children with autism who have the variation of 5-HTTLPR reported encountering more stress during pregnancy, compared with mothers who did not carry the variant.
The video below further illustrates the team's findings:
The researchers are careful to note, however, that this is an observational study and that further research is warranted.
"Though this was an observational study and future confirmation of this finding is needed, it's possible we could, one day, identify women who may be at a greater risk of having a child with autism when exposed to stress."
Dr. David Beversdorf