For children with autism and a class of genetic disorders, exposure to diagnostic ultrasound in the first trimester of pregnancy is linked to increased autism severity, according to study results reported Sept. 1. The study was conducted by researchers at UW Medicine, University of Washington Bothell and Seattle Children’s Research Institute.
The paper appears in Autism Research.
The study looked at the variability of symptoms among kids with autism, not what causes autism. The researchers found that exposure to diagnostic ultrasound in the first trimester is linked to increased autism symptom severity. The greatest link is among kids with certain genetic variations associated with autism; 7% of the children in the study had those variations.
Food and Drug Administration (FDA) guidelines recommend that diagnostic ultrasound be used only for medical necessity.
“I believe the implications of our results are to bolster the FDA guidelines,” said corresponding author Pierre D. Mourad, a UW professor of neurological surgery in Seattle. He is also a professor of engineering and mathematics at UW Bothell. As a UW Medicine scientist, he specialises in translational research on ultrasound and the brain.
Mourad said their results are related to the first trimester of pregnancy. Data from looking at the effect of ultrasound on the second and third trimester showed no link, he said.
The researchers used data from the Simons Simplex Collection autism genetic repository. The database is funded by the Simons Foundation Autism Research Initiative. The data was derived from 2,644 families among 12 research sites across the United States.
“There has been a real struggle in figuring out why there are so many kids with autism,” said lead author Sara Webb, UW professor psychiatry and behavioural sciences. “Where does this disorder develop from and how do kids get autism? And a second question is, why are kids with autism so different from each other? This study really looks at the second question. Within kids with autism, what are some of the factors that may result in a child having a good outcome or higher IQ or better language skills or less severity versus a child who maybe takes more of a hit and continues to struggle throughout life?”
Webb, in addition to her UW Medicine role, is a researcher at Seattle Children’s Center on Health Behavior and Development and the UW Center on Human Development and Disability.
She said the study team approached their work based on a three-part model explaining variability in kids with autism. The first is a genetic vulnerability to the disorder. Second is an outside stressor. And the third implies that the outside stressor has to impinge on a kid at a certain time.
Webb said a number of outside stressors have been proposed and investigated in autism. This study looked at only one of them – ultrasound.
As a mother of two, Webb said given what she knows now, she would not have ultrasound in the first trimester unless there is a medical necessity, and that includes knowing how far along the pregnancy is.
“If we can figure out this information in any other way, I would go with that,” she said. “It’s always worth considering that when we do medical procedures, there are great benefits but also risk.”
In an earlier study, Mourad and co-authors Webb, Abbi McClintic, a UW Medicine researcher in neurological surgery, and Bryan King, now a professor of psychiatry at the University of California, San Francisco, published a paper in Autism Research in 2014 that showed ultrasound exposure in pregnant mice caused autistic-like symptoms in their offspring.
Mourad said he and King wanted to study the issue further. They brought together a team with a wide range of autism experience. King, formerly with UW Medicine, had conducted several clinical trials with children with autism. Webb works in developing biomarkers in kids with autism. Raphael Bernier, UW associate professor of psychiatry and behavioural sciences and clinical director of the Seattle Children’s Autism Center, is among those analysing the Simon sample. Webb and Bernier are also with the UW Center on Human Development and Disability. Michelle Garrison, a UW research assistant professor of psychiatry and behavioural science in the Division of Child and Adolescent Psychiatry, specialises in statistics and epidemiology at the Seattle Children’s Research Institute.
Mourad said he and his colleagues now intend to look more closely into links between ultrasound and autism severity, as well as the possibility – thus far not shown – that ultrasound exposure could contribute to autism incidence.
(Source: University of Washington, Autism Research)