More time spent on social media is linked to a thinner cerebral cortex in young adolescents

New research published in the journal NeuroImage suggests that spending more time on social media is associated with physical differences in the developing brains of young adolescents. Specifically, children who spent more hours on digital platforms exhibited a thinner outer layer of the brain in areas responsible for attention, memory, and emotional control. These findings provide evidence that everyday digital habits might relate to how the brain physically matures during a highly sensitive period of growth.

Early adolescence is a period characterized by major physical, social, and mental changes. During this time, the brain undergoes a high degree of restructuring to prepare a child for adulthood.

At the same time, children are increasingly gaining access to smartphones and creating social media accounts for the very first time. Recent statistics suggest that a majority of young adolescents between the ages of 11 and 12 use these platforms regularly.

Scientists wanted to know if this widespread social media use is linked to how the brain develops. Past research has associated general screen time, like watching television or playing video games, with disrupted sleep, poor mental health, and physical changes in the brain.

Social media involves unique interactive elements that separate it from passively watching a movie or playing a single-player game. Because it engages different thought processes, scientists suspected that social media use might be associated with distinct patterns of brain development.

Previous studies on the topic often focused on older teenagers or lumped all screen time together into a single broad category. By isolating social media use, the researchers hoped to paint a clearer picture of how platforms designed for social interaction might influence the growing mind.

“I first became interested in social media research through caring for adolescents with eating disorders, many of whom described spending hours on social media viewing unrealistic body ideals and weight-focused content. These clinical experiences led me to study the broader mental health effects of social media use and to help inform guidance for families. Brain development is a critical area that remains less understood, which motivated this line of research,” said study author Jason Nagata, an associate professor of pediatrics at the University of California, San Francisco.

For their study, the researchers analyzed data from a large, nationwide project called the Adolescent Brain Cognitive Development Study. They focused on a specific group of 7,614 children between the ages of 10 and 13.

The scientists utilized a technique called structural magnetic resonance imaging to take detailed pictures of each child’s brain. This type of brain scan allows researchers to measure the brain’s physical characteristics, such as the thickness, volume, and surface area of the cerebral cortex.

The cerebral cortex is the wrinkled outer layer of the brain that handles complex functions like reasoning, language, and sensory processing. The researchers looked at these brain measurements and compared them to the participants’ self-reported social media habits.

The children completed surveys detailing how many hours they spent on social media during a typical weekday and weekend. On average, the adolescents used social media for just over half an hour a day, though some individuals spent considerably more time online.

The participants also answered a six-item questionnaire designed to measure addictive behaviors related to social media. This survey asked about habits such as unsuccessfully trying to cut back on app usage or feeling unable to stop scrolling.

To ensure their findings were as accurate as possible, the scientists accounted for a wide range of outside factors. They adjusted their mathematical models for the participants’ age, sex, race, genetic background, household income, and the education level of their caregivers.

They also factored in how much time the children spent on other types of screens, ensuring that the final results reflected social media use specifically. In addition to examining pre-defined regions of the brain, the researchers used an advanced computer algorithm to analyze the brain scans at an incredibly high resolution.

This highly detailed analysis allowed them to examine the brain without relying on artificial boundaries between different brain regions. The researchers found that higher average daily social media use was significantly associated with a thinner cerebral cortex.

Specifically, children who spent more time on social media tended to have a thinner outer layer across several widespread areas of the brain. These areas included regions within the frontal, temporal, occipital, and parietal lobes.

These specific brain regions overlap with networks that control executive functions, which involve planning, memory, and impulse control. They also overlap with networks responsible for visual processing and maintaining attention.

Additionally, the scientists noticed lower overall cortical volume in the right hemisphere of the brain among frequent social media users. They did not find a strong link between social media use and the surface area of the brain.

When looking at the addiction questionnaire, the scientists did not find any significant physical brain differences associated with social media addiction. The physical variations were tied strictly to the amount of time spent on the platforms rather than addictive behavioral patterns.

In the developing adolescent brain, a gradual thinning of the cerebral cortex is actually a normal part of growing up. This natural process is known as synaptic pruning, where the brain eliminates unused connections to become more efficient.

Excessive or accelerated thinning, however, can sometimes be a marker of abnormal development. Past research has linked overly rapid cortical thinning to difficulties with emotional regulation and a higher risk of psychiatric conditions.

“Greater social media use is associated with differences in brain structure,” Nagata noted PsyPost. “Social media use in young adolescents was linked to lower cortical thickness across the prefrontal cortices, temporal lobe, occipital lobe, and parietal lobe. Regions identified were in key nodes of the default mode network, prefrontal executive control networks, and visual processing and attention networks. However, we cannot conclude if these differences are a result of social media use or a predisposing factor.”

It is possible that children who naturally have a thinner cerebral cortex are simply more drawn to using social media. The researchers also noted that the physical differences they observed, while mathematically significant, were relatively small in size. The magnitude of these brain differences was comparable to the effects seen from watching television or reading books.

“Reduced cortical thickness is not necessarily something that is bad,” Nagata noted. “During development, our brains shrink as unnecessary neural connections are naturally removed, which improves neuronal efficiency. These findings should not be interpreted solely as something that is good or bad.”

“Additionally, given the cross-sectional design of this paper, we cannot determine if these alterations may be a consequence of social media use or if they precipitate social media use. Correlation does not imply causation. Further research is required to understand the directionality of these associations and to determine if there are any long-term behavioral consequences.”

The scientists also did not measure the type of content the children were consuming. Scrolling through educational videos likely engages the brain differently than experiencing cyberbullying or viewing highly curated lifestyle images.

Moving forward, the researchers plan to track these participants over several years to observe how their brains change over time. This long-term approach will help clarify if social media use accelerates brain changes or if pre-existing brain differences drive social media habits.

The scientists also hope to use functional brain scans in the future to see how the brain actively behaves while adolescents are using social media. Because many of the children in this study were under the age of 13, the researchers suggest their findings highlight a need for stronger age verification policies online.

The study, “Social media use and early adolescent brain structure: Findings from the Adolescent Brain Cognitive Development (ABCD) Study,” was authored by Jason M. Nagata, Kevin Bao, Stuart B. Murray, Pierre Nedelec, Racquel A. Richardson, Sahana Nayak, Elizabeth J. Li, Jennifer H. Wong, Eva M. Muller-Oehring, Aaron Scheffler, Fiona C. Baker, Andreas M. Rauschecker, and Leo P. Sugrue.