Study links screen time to lower brain development in preschoolers
Screen time use by infants, toddlers and preschoolers has exploded over the last decade, concerning experts about the impact of television, tablets and smartphones on these critical years of rapid brain development.
Now a new study scanned the brains of children 3 to 5 years old and found those who used screens more than the recommended one hour a day without parental involvement had lower levels of development in the brain’s white matter — an area key to the development of language, literacy and cognitive skills.
“This is the first study to document associations between higher screen use and lower measures of brain structure and skills in preschool-aged kids,” said lead author Dr. John Hutton, a pediatrician and clinical researcher at Cincinnati Children’s Hospital. The study was published Monday in the journal JAMA Pediatrics.
“This is important because the brain is developing the most rapidly in the first five years,” Dr. Hutton said. “That’s when brains are very plastic and soaking up everything, forming these strong connections that last for life.”
Studies have shown excessive TV viewing is linked to the inability of children to pay attention and think clearly, while increasing poor eating habits and behavioral problems. Associations have also been shown between excessive screen time and language delay, poor sleep, impaired executive function and a decrease in parent-child engagement.
“It’s known that kids that use more screen time tend to grow up in families that use more screen time,” Dr. Hutton said. “Kids who report five hours of screen time could have parents who use 10 hours of screen time. Put that together and there’s almost no time for them to interact with each other.”
In addition, the portability of today’s screens allow them to “follow kids everywhere.” Dr. Hutton said. “They can take screens to bed, they can take them to meals, they can take them to the car, to the playground.”
Even more concerning, say experts, are the young ages at which children are being exposed.
“About 90% are using screens by age 1,” said Dr. Hutton, who published a number of studies that used MRIs to research the impact of reading versus screen use by kids. “We’ve done some studies where kids are using them by 2 months old to 3 months old.”
The new study used a special type of MRI, called diffusion tensor imaging, to examine the brains of 47 brain healthy children (27 girls and 20 boys) who had not yet started kindergarten.
A diffusion tensor MRI allows a good look at the white matter of the brain, responsible for organizing communication between the various parts of the brain’s gray matter.
It’s the gray matter that contains the majority of the brain cells telling the body what to do. White matter is made up of fibers, typically distributed into bundles called tracts, which form connections between brain cells and the rest of the nervous system.
“Think of white matter as cables, sort of like the telephone lines that are connecting the various parts of the brain so they can talk to each other,” Dr. Hutton said.
A lack of development of those “cables” can slow the brain’s processing speed; on the other hand, studies show that reading, juggling or learning and practicing a musical instrument improves the organization and structure of the brain’s white matter.
Before the MRI, the children were given cognitive tests, while the parents filled out a new scoring system on screen time developed by the American Academy of Pediatrics.
The results showed that children who used more than the AAP’s recommended amount of screen time of an hour a day without parental interaction, had more disorganized, underdeveloped white matter throughout the brain.