A new study has found a link between screen time and brain development in preschoolers. Here's what concerned parents need to know.

We are all guilty of sticking our kids in front of the television so we can get a few things done, like make dinner or return a phone call. And yes, we feel badly about it sometimes, because it's well known that too much screen time is associated with a higher risk of obesity in kids, among other potential problems. But now research finds there's another reason parents should be as cognizant about limiting TV-time as possible: the more television kids watch, the less ready they may be for school. One study, published in the journal JAMA Pediatrics in November 2019, used diffusion tensor imaging—a type of MRI—to look at white matter in the brain. Researchers measured results of 47 preschool-aged kids' cognitive tests, and compared them with statistics about the preschoolers' screen-based media use (compiled by parents in a "ScreenQ" survey). Here are the findings: Children with a higher ScreenQ had lower "structural integrity and myelination" in the brain. More screen time, therefore, is associated with decreased language and literacy skills in preschoolers. According to CNN, lead author Dr. John Hutton, a pediatrician and clinical researcher at Cincinnati Children’s Hospital, stated: “This is the first study to document associations between higher screen use and lower measures of brain structure and skills in preschool-aged kids. This is important because the brain is developing the most rapidly in the first five years. That’s when brains are very plastic and soaking up everything, forming these strong connections that last for life.” These results are similar to findings from New York University, which appeared in the Journal of Developmental & Behavioral Pediatrics in April 2017. Researchers looked at 807 kindergartners of varying backgrounds. The kids' parents reported family income, and the number of hours of TV the kids watched on a daily basis. (Kids' video game, tablet, and smartphone engagement was not part of the study.) The conclusion: watching the tube for more than a few hours a day was associated with lower school readiness in kindergartners, especially among low-income families. Then, researchers assessed the peewee participants on fundamental school-readiness skills in math, understanding letters and words, and key cognitive and social-emotional competencies, such as working memory, cognitive flexibility, and inhibitory control. They found that when kids watched more than two hours of TV, their kindergarten-readiness was adversely affected. And as family incomes decreased, the link between TV viewing and drops in school readiness increased. Families near the poverty line (defined as having an annual income of about $21,200 for a family of four) saw the biggest drop. Interestingly, researchers noted no link between school readiness and TV watching in high-income homes (around $127,000 per year for a family of four). Researchers suggest that kids from high-income families may be watching more educational content, and that parents may be able to watch more programs with their kids, which has been found to promote learning. Both studies study reinforce the American Academy of Pediatrics (AAP) recommendation that kids ages 2 to 5 engage in just one hour of screen-time per day. But as most parents can attest, this is easier said than done. In fact, this New York University study's lead author Andrew Ribner, a doctoral candidate in the Department of Applied Psychology at NYU Steinhardt, said in a statement, "Given that studies have reported that children often watch more than the recommended amount, and the current prevalence of technology such as smartphones and tablets, engaging in screen time may be more frequent now than ever before." The takeaway for parents: Do your best to limit your child's screen time.