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 鈥渟tatistically significant association鈥� 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 offers new insight into that connection and the onset of ASD in early childhood.
Not all studies have drawn a clear cut correlation, however. A Canadian study that looked at the impact of increased screen time during the pandemic, found that parents of kids with and without autism reported both positive and negative impacts 鈥渋n nearly .鈥�
The large study that was published on 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 鈥� 251 kids or 76 per cent 鈥� were boys and 79, or 24 per cent, were girls, researchers said.
鈥淭he proportion of children with ASD increased as screen time increased,鈥� 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.
鈥淭his 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 鈥� genetic factors may be involved in the observed sex differences in the association between ASD and screen time.鈥�
Dr Azadeh Kushki, a senior scientist with the Autism Research Centre at Bloorview Research Institute who was not involved in the study out of Japan, but was the lead investigator for the Canadian study published last October, cautioned that it was important to distinguish correlation and causation, and said there could be a number of reasons why kids who get more screen time may also have a higher risk of autism.
Correlation is when two things change together, but one is not necessarily the reason or cause for the change in the other. Causation is when one action directly results in a specific outcome. In other words, correlation does not imply causation, an important concept in science and statistics.
鈥淲e're finding that kids who were watching more screen time at the age of one had a higher risk of autism, but this doesn't mean that increased screen time causes autism,鈥� said Kushki.
Screen time might be a marker 鈥� not a cause 鈥� for autism, she said. These children may have different interests, social motivations, sensory experiences, or other differences that may increase their affinity for screen time.
In the new study out of Japan, mothers were asked how many hours per day their children were allowed to watch TV when they turned one. Answers were categorized 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鈥檚 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, which only specified 鈥淭V or DVDs鈥� did not indicate if more interactive screen time, such as those on a tablet, was included in its questionnaire, which Kushki said is a relevant distinction.
鈥淥bviously there are factors that can help mitigate some of the negative effects of technology. For example, choosing content wisely,鈥� she said.
鈥淲hat is it that people are doing with screens?...are we playing video games or are we doing educational activities? Are we using this to connect with family and friends? Really the content and the pattern of use really matters and that really needs to be emphasized.鈥�
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.
鈥淚 think the issue of screen time is very, very complex, especially in the age of COVID. What we鈥檙e finding is that the impact is quite mixed,鈥� Kushki said
鈥淚t鈥檚 really the quality of use versus the quantity of use.鈥�
