In the largest and most comprehensive study to date, Beersheba researchers have found abnormalities in fetal head growth in children diagnosed with autism spectrum disorder (ASD) during the first years of life.
ASD, a neurological and developmental disorder that begins early in childhood and lasts throughout a person’s life, affects how a person acts and interacts with others, communicates and learns. It is diagnosed more commonly in boys than in girls and includes what used to be known as Asperger syndrome and pervasive developmental disorders.
One of the most common developmental disabilities, it involves a broad range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication. People with autism have differences in the way their brains develop and process information. As a result, they face significant communication, social, and behavior challenges.
Among the problems are delayed speech and language skills; repeating the same phrase over and over; having a flat, robotic speaking or singsong voice; not using or rarely using common gestures (pointing or waving) and not responding to them.
Despite evidence for the prenatal onset of abnormal head growth in children with ASD, studies on fetal ultrasound data in the disorder have been limited and controversial.
Lead author Prof. Idan Menashe of public health department in the Faculty of Health Sciences at Ben-Gurion University (BGU) of the Negev and Dr. Gal Meiri, head of the pediatric psychiatry unit at Soroka University Medical Center (who is also medical director of BGU’s National Autism Research Center) published their findings in the journal Child & Adolescent Psychiatry under the title: “Association Between Abnormal Fetal Head Growth and Autism Spectrum Disorder.”
“This research is representative of the ongoing collaboration between doctors and researchers at the National Autism Research Center of Israel,” said Meiri. “This collaboration provides a strong foundation for in-depth studies based on our database that enables us to identify risk factors and to characterize ASD sub-types. Other studies at the center help us understand ASD development, the connection between biological, developmental, and behavioral characteristics. We hope to be able to personalize care in the future during the diagnosis and perhaps even before the official diagnosis.”
The Beersheba team compared prenatal ultrasound data from the second and/or third trimester of 174 children later diagnosed with ASD at the national center to the ultrasound data of their unaffected siblings as well as to ultrasound data of normally developed children from the general population.
During second trimester ASD and typically developed sibling fetuses had heads with significantly smaller diameters, but these differences became statistically indistinguishable in the third trimester. Interestingly, head biometric measures varied by sex, with male fetuses having larger heads than female fetuses within and across groups.
They found that abnormal head growth associated with autism spectrum disorder begins in uterus and that fetuses later diagnosed with ASD and their typically developing siblings have narrower heads during mid-gestation compared to the control group. This suggested that such fetus growth abnormality is a familial trait of ASD.
Another finding was that ASD-related head growth abnormalities are set by the sex of the fetus with male and female fetus showing different head shapes during gestation. Fetal head abnormalities also appeared to be linked with the severity of ASD.
“Previous studies have found abnormalities in head growth among children with ASD during childhood, but prenatal studies about this phenomenon had inconclusive results. Our findings suggest that abnormalities in head growth that are associated with ASD begin in mid-gestation and that such crucial diagnostic information can be gleaned from prenatal ultrasounds,” declared Menashe.