The Starset SocietyWhile that message has been spread on social media, researchers are just beginning to understand how the devices affect the mind
In the post, Ruh claimed two or more hours of mindless scrolling daily causes reduced gray matter in key brain regions that are crucial for decision-making and information processing. As a call-to-action, he recommended that people break from their “brain rot” by going outside and doing “real” things, like hiking and surfing.
The post cited a 2020 study published in Addictive Behaviors that used magnetic resonance imaging (MRI) to reveal a correlation between smartphone addiction and lower gray matter volumes in certain areas of the brain. Gray matter is a type of brain tissue that plays an important role in maintaining memory, as well as regulating emotions and movement. Ruh’s post received over 340,000 likes on Instagram.
Ruh’s post was indicative of a broader trend; “brain rot” was voted the Oxford Word of the Year 2024. The term is partially defined as the “supposed deterioration of a person’s mental or intellectual state, especially viewed as a result of overconsumption of material (now particularly online content) considered to be trivial or unchallenging.” Increasingly, the term has been incorporated into scientific conversations as an informal way to characterize how peoples’ brains may be negatively impacted by their internet devices—though it is not a real scientific term. Ben Becker, a neuroscientist at the University of Hong Kong, warns that scientific application of the term is misleading and can lead to unfounded fears.
“Posts like these [by Ruh] will not raise awareness or promote responsible use,” Becker explains. “It carries the dangers of pathologizing everyday behavior and stigmatization.”
Over the past few years, the idea implied by ”brain rot,” that our smartphones and the applications on them—such as the internet and social media—may negatively impact our brains, has increasingly appeared throughout the media. In June 2024, the Guardian reported on a study suggesting that young people with internet addiction experience brain changes that could make them more vulnerable to other addictive behaviors. And in March 2025, CBS News reported on a 2021 study that used MRI images to identify high brain activity in smartphone-addicted brains that made them easily distracted, which the researchers informally referred to as “brain rot.”
Since the Covid-19 pandemic, parents, politicians and psychiatrists have raised concerns over rising levels of depression and anxiety in young people. The World Health Organization reported that in the first year of the pandemic, rates of anxiety and depression increased by about 25 percent globally. According to Becker, this deterioration of adolescent mental health has paralleled a rise in apparent smartphone dependency, making it easy for people to conclude that there must be a relationship between these two events—and that there might be a neurological basis to them.
Since at least the early 2010s, scientists have conducted studies on how smartphone use might affect the structure of our brains. Though Becker notes that findings remain inconsistent, these studies have most commonly reported decreases in volume in certain regions of the brain that are associated with emotional regulation, cognitive control, reward and motivation, but experts say that research is still in its early stages. Many of the studies, Becker points out, are short-term with small sample sizes. In addition, scientists still don’t agree on the use of specific terms, such as “smartphone addiction.”
“The prototype of the smartphone as we know it these days was introduced with the iPhone in 2007. Meanwhile, we have more than five billion people who use such a device on a daily level,” says Christian Montag, a neuroscientist at the University of Macau. “Obviously, there are a lot of questions to be answered around it. Namely, do we over-rely on these technologies? Does this have a lasting impact on the brain and our cognitive function?”
Robert Christian Wolf, a clinical psychiatrist at Heidelberg University, says he first became interested in studying the connection between smartphone addiction and brain function in 2016, when he met a young patient who appeared to exhibit a severe clinical problem centered on their smartphone use.
According to Wolf, the core problem of this patient was their inability to cease using the device, specifically a popular communication app. The patient would use their phone upward of eight hours a day, and Wolf said the use was associated with deteriorations in their mood and difficulties in concentration.
“We did all the differential diagnoses to see if this was something that occurs in isolation [or] something that’s motivated by other mental disorders, and to our surprise, basically, it was a pretty pure behavioral addiction,” Wolf says.
Wolf and his team concluded that the condition represented a behavioral addiction rather than just excessive use. They based their diagnosis on several “hallmark features” associated with addictive disorders—including a clear loss of control over duration and frequency of smartphone use and discomfort when the device was absent.
Since then, Wolf and a team of researchers have worked to uncover whether there might be a neurological basis to addictive smartphone use.
The 2020 study “Structural and functional correlates of smartphone addiction” referenced by Ruh was one of the first papers Wolf co-authored on the subject.
In the study, Wolf—alongside a team of researchers at Heidelberg University—recruited 48 smartphone users between the ages of 18 to 30. Participants were divided into two groups, people who exhibited characteristics of smartphone addiction and people who did not. The addictive group was determined based on a “Smartphone Addiction Inventory,” developed by researchers in Taiwan in 2014, in which participants self-reported their levels of compulsive use, tolerance and withdrawal.
Using MRI, researchers found that individuals who exhibited signs of smartphone addiction showed lower gray matter volumes in the left anterior insula, left inferior temporal and parahippocampal cortex of their brains. Respectively, those areas are broadly associated with perceiving empathy, memory and self-regulation.
For Wolf, these findings suggest that lower volumes in these brain regions may make resisting compulsive behaviors—such as those leading to excessive smartphone use—more difficult. In addition, Wolf explains that while structural brain changes do not necessarily imply brain damage, they could suggest that brains have adapted in a way that reinforces compulsive smartphone use.
Wolf emphasizes that because the study was cross-sectional, scientists cannot yet draw conclusions from it. The study just captures a snapshot of what different users’ brains look like. To better measure the impact of problematic smartphone use, researchers would have to document gray matter changes over an extended period of time.
Montag notes that the study low number of participants. “For sure, the study has its merits by demonstrating an important approach [of] how to study this phenomenon,” he says. “But the findings are, from my perspective, preliminary.”
The research of Wolf’s team is among 26 MRI-based studies that neuroscientists Montag and Becker analyzed in their literature review of the emerging field, in which the brain scans of young people who use smartphones a lot are compared to those who don’t. The 2023 study published in the journal Psychoradiology found that many studies so far have been cross-sectional, rely on small sample sizes and don’t have a strong neuroscientific framework for determining smartphone overuse yet.
“Without real long-term studies, we can’t make clear conclusions,” Becker says. “In the end, if you compare people who use smartphone or social media six hours a day with those who use it maybe 20 minutes a day, the groups will be probably already different from the start.”
Besides the fact that preliminary research has often been limited to short-term studies with relatively small sample sizes, Becker emphasizes that smartphone addiction is a contested term. The paper co-authored by Wolf, too, acknowledges that the term is controversial due to arguments that the condition lacks the severity required of true addiction, and that smartphones are but a way of accessing different applications, such as social media and the internet.
Tayana Panova, a psychologist at Ramon Llull University in Spain, for example, says that widespread fear over smartphone addiction exists without proof that it is a real disorder.
Panova hypothesizes that the term “smartphone addiction” gained popularity because of the similarities people have identified between high smartphone use and addictive behaviors. She says that the term “smartphone addiction” is a way for people to emphasize the problem of people using their phones in an excessive way. “We often call ourselves ’addicted‘ to things we do a lot, in the same way we call ourselves ’obsessed‘ with things we think about a lot,” Panova says. “However, doing a certain behavior a lot does not necessarily mean you have an addiction to it.”
According to Panova, although high smartphone use may have similarities to addiction, its components and consequences may not rise to the level of severity required for such a diagnosis. “For example, you may think about your phone repeatedly during the day if you forget it at home,” she says, “but this is not equivalent to the deep discomfort of withdrawal.”
Panova adds that by referring to excess levels of smartphone use as “addictive” and studying it within an addiction framework, scientists risk misguided research. She emphasizes that smartphones are not a homogenous substance like drugs—each smartphone holds dozens of different applications and each person uses their smartphones in different ways. For example, we can’t link general smartphone overuse with depression if, say, people are using the device to receive support from their friends and family—it’s much more complicated than that.
Montag adds that as research grows, it’s important for researchers to establish an objective layer of data to characterize “dysfunctional” smartphone use. For example, researchers should use automatic screentime reports generated by the phone rather than self-reporting by study participants.
Although Panova says smartphone use can’t be characterized as “addictive” yet, device overuse can still be harmful, as various associations established by studies like Wolf’s have hinted at. She emphasizes that to truly gain insight into smartphone effects on well-being, scientists must take a much closer look at the devices’ roles in each individual’s life. In other words, scientists must more closely identify which applications people are using and what purposes they may be serving, rather than simply drawing conclusions based on overall smartphone use.
Montag says that the conclusion that smartphones may be changing our brains is not necessarily unlikely, given the brain’s neuroplastic nature. Neuroplasticity refers to the brain’s ability to change its structure and function in response to external factors such as new experiences, environments or injuries.
Parisa Gazerani, a neurobiologist at Oslo Metropolitan University, says that although it’s plausible that repetitive digital input could lead to structural adaptations, particularly in developing brains that hold high levels of neuroplasticity, it’s important that people recognize that not all brain changes are harmful.
“There is a significant difference between passive overuse that displaces meaningful activity and intentional digital engagement that supports learning, creativity or connection,” Gazerani says.
Montag emphasizes the need for more long-term research to better understand the relationships between smartphone use and brain chemistry.
Wolf says once we understand the mechanism behind smartphone overuse, “there is an opportunity for prevention and education.”
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