Environmental Factors May Up Risk of Autism for Some Preemies

Babies born very prematurely face a much greater risk for developing autism in later childhood, and according to a new study, these brain differences can be seen as early as the neonatal period (birth to one month of age).

The findings, which are published in the journal Cerebral Cortex, suggest that very early environmental factors, such as birth complications or surgery, can contribute to autism.

Extremely preterm babies have much greater survival rates now due to medical advances. However, babies born more than 13 weeks prematurely run a serious risk of brain damage, autism, ADHD, and learning difficulties.

These babies are exposed to numerous stress factors during a period critical to brain development, and it is possible that this plays a key role in the development of autism spectrum disorder (ASD).

For the study, the researchers examined over 100 babies who had been born extremely prematurely (i.e. before week 27, the beginning of the third trimester). With the parents’ permission they studied the growth of the babies’ brains using magnetic resonance imaging during the neonatal period, and then screened the children for autistic features at age six.

“We were surprised by how many — almost 30 percent — of the extremely preterm-born children had developed ASD symptoms,” said Dr. Ulrika Ådén, researcher at the Department of Women’s and Children’s Health at Karolinska Institutet and neonatologist at the Neonatology clinic at Karolinska University Hospital in Sweden. “Amongst children born after full term pregnancy, the corresponding figure is one percent.”

The findings revealed that it was more common in the group of children who had developed ASD for there to have been complications during the neonatal period, such as surgery, than it was amongst their prematurely born peers who had not developed ASD.

Already in the neonatal period, long before the children had manifested signs of autism, differences could be seen between the extremely preterm babies who went on to develop ASD and those who did not. Researchers found diminished growth in brain areas involved in social contact, empathy, and language acquisition — functions that are impaired in autism.

So while autism is generally attributed to genetic factors, the new findings suggest that birth weight and complications can contribute to this risk.

“Our study shows that environmental factors can also cause autism,” Ådén said. “The brain grows best in the womb, and if the developmental environment changes too early to a life in the atmosphere, it can disrupt the organization of cerebral networks.

“With new therapeutic regimes to stimulate the development of such babies and avoid stress, maybe we can reduce the risk of their developing ASD.”

Source: Karolinska Institutet

Preterm baby photo by shutterstock.