NIH Study Probes Impact of Heavy Screen Time on Young Brains

In brain scans of 4,500 children, daily screen usage of more than seven hours showed premature thinning of the brain cortex.

(Bloomberg) -- Brain scans of adolescents who are heavy users of smartphones, tablets and video games look different from those of less active screen users, preliminary results from an ongoing study funded by the National Institutes of Health show, according to a report on Sunday by “60 Minutes.”

That’s the finding of the first batch of scans of 4,500 nine- to 10-year-olds. Scientists will follow those children and thousands more for a decade to see how childhood experiences, including the use of digital devices, affect their brains, emotional development and mental health.

In the first round of testing, the scans of children who reported daily screen usage of more than seven hours showed premature thinning of the brain cortex, the outermost layer that processes information from the physical world.

NIH study director Gaya Dowling cautioned against drawing a conclusion from the early findings.

“We don’t know if it’s being caused by the screen time. We don’t know if it’s a bad thing,” Dowling said in Sunday’s broadcast on CBS. “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.”

Early results from the $300 million study, called Adolescent Brain Cognitive Development (ABCD), have determined that children who spend more than two hours of daily screen time score lower on thinking and language tests. A major data release is scheduled for early 2019.

Teenagers now spend an average of 4 1/2 hours a day on their mobile phones, “60 Minutes” reported.

(An earlier version corrected the spelling of National Institutes of Health.)

To contact the reporter on this story: Lisa Lee in New York at

To contact the editors responsible for this story: James Ludden at, Virginia Van Natta, Ros Krasny

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