Research hyperlinks display time to autism, however issues abound | Spectrum
Associate Teaching Professor, University of Stanford
A study published yesterday in JAMA Pediatrics prompted headlines such as “Boys who watch television for at least two hours a day are 3.5 times more likely to be diagnosed with autism by age three, a study found.” spectrum asked statistics expert Kristin Sainani, Associate Teaching Professor of Epidemiology and Population Health at Stanford University in California, for her thoughts.
Headlines this week were a new study suggesting that 1-year-old boys but not girls who spend two to four hours a day in front of the television have one elevated chance being diagnosed with autism by the age of 3. So what can researchers take away from the paper?
The aim of the study was to understand how screen time affects a child’s likelihood of developing autism. To answer this question, they recruited a large number of participants: more than 84,000 women from 15 regional health centers across Japan. Each woman was pregnant between January 2011 and March 2014. When the children from these pregnancies were 1 year old, the women answered a multiple-choice survey: How many hours a day does your child spend watching television or DVDs? The possible answers ranged from zero to more than four hours. Most women said their child watches for less than two hours a day.
The women answered the survey question again when their child turned 3 years old, and they also indicated whether the child had been diagnosed with autism “by a doctor from the age of 2 to now,” according to the study. These types of surveys are inherently problematic because they can introduce bias. A woman who underreports her child’s television viewing because it is not socially acceptable may also be less likely to report an autism diagnosis.
In the study, only 330 out of 84,030 women reported that their child had hAutism was diagnosed at age 3, giving a prevalence of about 0.4 percent. According to the study, there were three times as many autistic boys as autistic girls, and the proportion of children with autism increased as screen time increased.
But the households in which 1-year-olds watch little or no television are likely to be different from those in which babies watch television for more than two hours a day.
The results are also difficult to assess because the study lacks detailed information on variables correlated with infant television viewing. Age, parental attitudes, and whether or not a child has a TV in their bedroom are all positive predictors of screen time, according to a 2012 paper. These factors were either not measured or only roughly considered in the new study.
The researchers controlled for maternal age and socioeconomic status, but only in a binary fashion. For example, women were lumped together if they were over or under the age of 19, and households were similarly lumped together if they were above or below the poverty line.
A better way to adjust for each mother’s age and socioeconomic status would have been, instead of this, to use a larger, more nuanced gradation of values. The new paper’s findings may also conflict with previous work; spent a lot of time watching television no relation to language or visual motor skills by the age of 3, according to a 2009 study paediatrics. In this more than 10-year-old study, the authors controlled for household income and maternal education, both of which were independently associated with the time children spend watching television.
All this is to say Without appropriate adjustment for confounders, any association between young children’s television viewing and autism is difficult to assess.
Cite this article: https://doi.org/10.53053/TBEO7836