Historic Study Indicates Relation Between Screen Time and Brain Changes

The National Institutes of Health is conducting an unparalleled study into the effects of screen time on adolescents. The Adolescent Brain Cognitive Development study (ABCD study) has recruited over 11,000 adolescents to monitor for ten years, including regular MRI and other brain scans, to find out the effects of numerous outside influences including substance use, sports injuries, and screen time.

Last month, the ABCD study released a new set of data points that Dr. Delaney Ruston, creator of the documentary Screenagers, has reviewed and broken down for the layman on her blog, Tech Talk Tuesdays.

From Dr. Ruston:

The study just released included only the first cohort of 4,500 kids and it gives data based on questionnaires and MRIs of their brains at one moment in time. Researchers found that kids who spent more than 7 hours a day on screens, on average, had a thinner outer layer of their cerebral cortex than kids who spent less time on screens. The cerebral cortex is the area that houses ‘executive functioning’ —ie, higher order thinking, such as data consolidation, problem-solving and planning. It also helps us regulate our responses to emotions that come from deeper areas of the brain.

Babies are born with many more brain cells than they will end up with as adults. Why so many cells at birth? The hypothesis is that this abundance of cells gives humans incredible adaptability to whatever environments they find themselves. As babies grow older and have experiences, these experiences dictate how neurons begin to lay down patterns. Neuronal connections that are not used, start to be pruned away. Evolutionarily, it is important that the brain loses some of what it does not use because running a brain takes a lot of energy—in fact 20% of the food we eat goes just to support the brain. Pruning promotes efficiency.  

The researchers revealed thinner cortexes of these 9 and 10-year-olds. The level of thinning found is what one finds on MRIs for older children. This is why this is being called premature thinning. One could see this as a bad thing, that the brain is consolidating neurons earlier than it normally would.  On the flip side, one could say that the brain appears to be maturing faster, so isn’t that a good thing?

Early maturation can sound good but the ABCD researchers found that this thinning in the cortex was correlated with lower ‘crystalized’ intelligence. Crystalized refers to the knowledge that youth glean from simply living life, such as vocabulary (as opposed to ‘fluid’ intelligence which is not as much about ‘what is known’ as opposed to ‘how something is known’).”