Baby boys with more screen time associated with autism spectrum disorder, study suggests

TORONTO —
Boys who were in front of the screen for longer periods at the age of one had a greater association with autism spectrum disorder (ASD) at the age of three, a new cohort study from Japan suggests.

Researchers from the University of Yamanashi found a “statistically significant association” among boys between the amount of screen time they received at an early age and being diagnosed with ASD later, but found no association between ASD and screen time among girls.

Earlier studies suggested similar associations between screen time and ASD characteristics, but there have been few studies that looked at screen time at one year of age, according to researchers. This study, published on Monday in JAMA Pediatrics, offers new insight into that connection and the onset of ASD in early childhood.

The large study looked at data from more than 84,000 mothers and their children collected between January 2011 and March 2014. A total of 330, or 0.4 per cent, of the children were diagnosed with ASD by the time they were three years old. More than three quarters of the children – 251 kids or 76 per cent – were boys and 79, or 24 per cent, were girls, researchers said.

“The proportion of children with ASD increased as screen time increased,” researchers wrote in their paper. They noted that screen time was similar for both boys and girls, but they did not find an association between screen time and ASD among girls.

“This result could be due to the higher prevalence of the disorder in boys. Previous studies on the genetic factors that contribute to the development of ASD have not yet explained the male predominance in ASD … genetic factors may be involved in the observed sex differences in the association between ASD and screen time.”

In the data that was analyzed, mothers were asked how many hours per day their children were allowed to watch TV when they turned one. Answers ranged from no screen time, less than one hour, one hour or more but less than two hours, two hours or more but less than four hours, and four hours or more. When the child turned three, the same questions were asked in a follow-up survey that also included questions on whether the child had been diagnosed with either autism, Asperger’s syndrome, or pervasive developmental disorder after the age of two.

Data analysis found a significant difference among boys who reportedly had between two to under four hours of screen time, researchers said.

One limitation of the study was that the diagnoses and screen time were based on parental reports, which may have resulted in reporting bias. In addition, given ASD is still in a developmental stage at a young age, mild cases may not have been diagnosed yet at the age of three, so the study may also be biased towards those with severe ASD, the authors noted.

The study also made an effort to adjust for variables like a predisposition to ASD through standardized screening questionnaires, anxiety disorders and other mental and neurological illnesses, as well as socioeconomic factors, but researchers acknowledged that further research was needed to look at other factors involved.