NIH researchers found that nine- and 10-year-old children who spent more than seven hours a day using such devices exhibited premature thinning of the cortex, the brain's outermost layer, which affects memory, attention, perceptual awareness, thought, language and consciousness.
A 2014 study by researchers at McGill University of 188 children and adolescents was the first to reveal an association with cortical thickness and IQ increases. In general, the cortex begins to thin at the age of five or six. MRI scans of the participants' brains revealed that over two years people with significant increases in IQ did not undergo the expected cortical thinning while people with significant decreases in IQ had significant cortical thinning. People who did not exhibit IQ changes underwent the expected cortical thinning.
"We don't know if it's being caused by the screen time. We don't know yet if it's a bad thing," Gaya Dowling, an NIH doctor working on the project, said in a recent interview regarding the preliminary findings with the CBS news program "60 Minutes."
"It won't be until we follow them over time that we will see if there are outcomes that are associated with the differences that we're seeing in this single snapshot."
"What we can say is that this is what the brains look like of kids who spend a lot of time on screens. And it's not just one pattern," Dowling said.
The study, which scanned the brains of 4,500 children, also found that kids who spent more than two hours a day on screens scored worse on language and reasoning tests. The end goal of the study is to determine whether screen time is addictive by studying 11,000 children during the $300 million study. Data from the study will be released in 2019.
"In many ways, the concern that investigators like I have is, that we're sort of in the midst of a natural kind of uncontrolled experiment on the next generation of children," Dimitri Christakis, a pediatrician and epidemiologist at the University of Washington School of Medicine, told "60 Minutes." Christakis also helped develop the current American Academy of Pediatrics' guidelines on screen time.
According to those guidelines, children 24 months or younger should mostly stay away from screens, while children between the ages of two and five should limit screen time to one hour per day.
Christakis did not immediately respond Monday afternoon to Sputnik's request for comment.