Too much time looking at tablets, smartphones and television screens may actually be affecting brain development in young children, a new study has found. 

Researchers at the Cincinnati Children’s Hospital Medical Center found that preschool-age children who get more screen time than doctors recommend have differences in parts of the brain that support language, literacy and self-regulation. The study, published recently in JAMA Pediatrics, found that there were actual structural differences in the brain related to screen-based media use.

The study involved 47 children between 3 and 5 years old, and their parents. They were asked detailed questions about screen use, and their answers were scored against guidelines put out by the American Academy of Pediatrics. The kids also had their brains scanned in an MRI machine.

The scans revealed that kids who spent more time in front of screens had what the authors call lower “white matter integrity.” The integrity of that structure is associated with cognitive function, and it develops as kids learn language. 

Though researchers noted it’s not clear how these changes affect child development, they said the results raised questions about using screen-based media “during this rapid, formative state of brain development.” 

"Screen-based media use is prevalent and increasing in home, childcare and school settings at ever younger ages," Dr. John Hutton, the author of the study. "These findings highlight the need to understand effects of screen time on the brain, particularly during stages of dynamic brain development in early childhood, so that providers, policymakers and parents can set healthy limits."

Currently, the AAP recommends children ages 2 to 5 limit screen use to 1 hour per day, and that children 18 to 24 months only watch children’s programming with their parents to help them understand what they're seeing. Children younger than 18 months, they say, should avoid use of screen media other than video-chatting.