Epidemiologist Miguel Ángel Martínez-González, professor of Public Health at the University of Navarra and visiting professor at the University of Harvard, argues that the abuse of internet-connected mobile phones "is responsible" for the mental health problems detected in children and adolescents in recent years. He aligns with American psychologist Jonathan Haidt, author of The Coddling of the American Mind, who has been criticized for overstating the relationship between the digital environment and the decline in childhood well-being without solid scientific evidence. The Spanish doctor follows Haidt's path and argues that "there is an increasing number of studies that no longer just show a correlation but prove that screens are the cause or one of the causes of an unprecedented neuropsychiatric epidemic among minors."
The issue is complex and has its nuances. Technology brings undeniable advancements, and it would not be fair to attribute all responsibility for the increase in mental health problems in children and adolescents solely to it, as it seems to be a multifactorial phenomenon. However, more experts are denouncing the "risks" of excessive exposure. Martínez-González, who has led major epidemiological studies and is among the top 10 most cited researchers in his field in Spain, sees "a shift in trend" in scientific literature, especially since the report from the US Surgeon General in 2023, which warned that "social media, while it may have benefits for some children and adolescents, also poses a profound risk of harm to their mental health and well-being."
Among the numerous studies cited in the report by the top US public health authority, two randomized controlled trials are mentioned. The first one, conducted with college students, states that limiting social media use to 30 minutes a day for three weeks "significantly improved the severity of depression." Another study published in the American Economic Review indicates that deactivating Facebook for four weeks increased life satisfaction.
On the other hand, scientific literature presents a significant number of studies that report a neutral or even positive effect of screens. For instance, an umbrella review of over 100 meta-analyses and around 2,500 papers published in Nature in 2023 observes small effects that vary depending on the type of use and context. Martínez-González believes that in this work, "studies that are not combinable are mixed, with different exposure times, which weakens the effect." "It's the same haze that occurs with another frequently cited study, published in The Lancet Regional Health, which has numerous flaws. The lack of demonstration of effects does not mean in any case that they do not exist or that screens are harmless," he adds.
The qualitative leap in research has occurred with the transition from observational studies, which demonstrated a mere association, to intervention studies with randomized design and control group, the best way to achieve causal evidence without exposing participants to adverse effects.
In his presentations, Martínez often mentions an experimental study published in JAMA in 2024 conducted with cluster randomization, where groups of individuals are randomly assigned to different intervention groups. For two weeks, all devices of an entire family were replaced with a basic phone without internet, while another family continued using smartphones. Well-being was measured at the beginning and end of the experiment, showing a "positive impact on children's psychological symptoms, particularly in mitigating internalized behavioral problems and improving prosocial behavior."
He also refers to another intervention study from the University of Bath (UK) in 2022, which concluded that being without social media -Facebook, Twitter, Instagram, and TikTok- for a week leads to "significant improvements in well-being, depression, and anxiety." "I don't know any medical specialist who isn't alarmed by the increase in depression, anxiety, self-harm, anorexia, and suicide attempts in children and adolescents," expresses Martínez-González.
Parents' Protest in 10 Cities
Parents, teachers, and childhood experts will gather this Saturday at 11:00 in 10 Spanish cities to demand a legal minimum age for smartphone access and a "digital de-escalation" in schools.
The protest reflects a new social phenomenon that has garnered support across the political spectrum, from the anti-screen law proposed by Sira Rego (IU) being processed in Congress to the decree by Isabel Díaz Ayuso (PP) limiting devices in classrooms and prohibiting homework with tablets at home.
David Ezpeleta, vice president and head of the Neurotechnology and Artificial Intelligence Area of the Spanish Society of Neurology, notes that for about a decade, "coinciding with the widespread use of social networks and intensive use of new technologies, behavioral alterations and structural changes in the brain have been observed not only in young people but also from early childhood due to overexposure to the digital environment."
Contact with everyone within screens leaves a mark on the brain's wiring. "In the youngest, in preschool ages, alterations in myelination in neuronal connections in areas responsible for language and literacy have been observed," details Ezpeleta. Imaging tests, such as PET and CT scans, are used to quantify and indicate the impact of intensive and harmful use of the "digital pacifier," as shown in a study in JAMA Pediatrics with resonances illustrating this report.
Clinicians use magnetic resonance imaging to study nerve tracts, the extensions of neurons that connect different regions of the brain and the rest of the central nervous system. In preschoolers, more hours in front of screens are associated with less developed "internal highways" in the brain. The images show nerve tracts where this difference between preschoolers exposed to screens and those not exposed is observed. A lower number of these "neuronal highways" built throughout childhood can lead to "alterations in language development, attention, memory, and learning," explains Ezpeleta.
Leaving devices with children without parental control alongside the permissiveness to "wander through the content of networks" are actions that "damage the plasticity of a developing brain." Ezpeleta, like other researchers, and as stated in a recent editorial in the scientific journal Nature -"Do screens harm teenagers? What can scientists do to find answers"-, seeks not only the how but also the why, as well as the reversibility of effects on an immature organ.
"We must not demonize but educate in use, making it healthy and productive, both at home and at school," states the neurologist. And it is essential to remember, he points out, that "the time spent on digital devices takes away from other activities: physical exercise, social relationships..." In the same vein, the editorial in Nature highlights that "whether technology helps, harms, does both, or neither probably depends on each person's background, the social media platforms they use, and the content they view."
An example was recently published by a group of researchers from the University of Cambridge in an article in Nature Human Behaviour. They analyzed a sample of over 3,000 adolescents aged 11 to 19 in the United Kingdom, and their conclusion was that those with mental health problems spent an average of 50 minutes more per day on social media compared to those who did not suffer from them. According to Ezpeleta, this study once again highlights that "digital media has become an integral part of adolescents' lives." Therefore, "we must recognize the negative effects," urges the neurologist.
"If after 10 minutes of use, they are asked to stop, the device is taken away, and they become angry, we are facing an addiction problem that will affect their academic performance," he says. In the journal Dialogues in Clinical Neuroscience, several reviews also point to these brain effects.
Neurologist Ezpeleta argues that "excessive time with the mobile phone" should not be in vain, "but should be used for valuable things, such as expanding knowledge in a subject," without "subleasing capabilities to technology." Ezpeleta emphasizes the importance of "children and adolescents reading on paper, writing by hand, and underlining ideas." "This constitutes a neuroprotective factor, as we have verified," he emphasizes. A study from the University of Hong Kong, published in Early Education and Development, addressed changes in the brains of children under 12 through 33 studies using neuroimaging technology to measure the impact on over 30,000 participants. The conclusion is that screen time negatively influences the brain function necessary for attention, executive control abilities, inhibitory control, cognitive processes, and functional connectivity.
A healthy use of social media "does not harm the brain or make the user aggressive," Ezpeleta emphasizes. "But we know that many adolescents suffer if their post does not get likes or the expected feedback," says the neurologist, highlighting how anxiety disorders and disappointment can then arise.
"Source of Distraction in Class"
Regarding the impact on learning, the PISA 2022 report shows that students who used digital devices in school for one hour a day for recreational or learning activities scored better than those who did not use them, but results worsened after one hour for leisure and three hours for learning. The OECD does not demonize technology and considers it "a means to engage students in more interactive teaching," but also sees it as "a source of distraction in class that can be detrimental to learning."
In another study with random assignment and a control group conducted at the "highly competitive" U.S. Military Academy West Point, where "incentives to pay attention in class are particularly high," it was observed that "allowing the use of computers in the classroom reduced students' average performance on final exams by approximately one-fifth of a standard deviation."
Then there is the SAPA project, another study with nearly 400,000 participants recruited between 2006 and 2018 and between 2011 and 2018 in the U.S. "This study demonstrates a reverse Flynn effect," explains Martínez-González. "If throughout the 20th century the average IQ had increased generation after generation, with the widespread use of internet-connected mobile phones, we have become less intelligent, especially young people."
Titled Generación Zombi (Paidós), Javier Albares, a neurophysiologist and member of the Spanish Sleep Society and the European Sleep Research Society, has analyzed this issue from various perspectives. In his book, he reviews scientific literature dedicated to the effects and argues how "digital devices influence academic performance and the low quality and quantity of sleep, factors that multiply negative consequences." He also points out that "our ancestral physiology does not need screens, it is not adapted to the rapid changes in the digital world that have occurred in the last 20 years."
The impact on adolescents' psyche is a major concern, "and a significant one," warns Ezpeleta. Dysmorphia and eating disorders along with depression and aggressiveness "develop more easily behind closed doors in the room while browsing social media," he adds. In a review by Spanish researchers, published in Journal of Epidemiology and Community Health, the increase in levels of body dissatisfaction, higher incidence of anorexia, bulimia, sleep quantity and quality problems, as well as a higher risk of depression and suicidal behaviors, is analyzed.
Suicide Attempts
"I am completely convinced that there is causality," says one of the authors, Professor Almudena Sánchez-Villegas, dean of the Faculty of Medicine at the Public University of Navarra, who is working on a mental health project measuring the lifestyles of 2,050 adolescents. In the preliminary results, she has already found "a clear association between screen use and depressive and anxious symptoms and the risk of suicide," although longitudinal results from this cohort, which will be monitored, will need a couple of years to be seen.
Clinical psychologist Francisco Villar, coordinator of the suicide prevention program for minors at the Sant Joan de Déu Hospital in Barcelona, agrees with her. He mentions that in a decade, the number of minors admitted to psychiatric emergencies (the most severe cases) at this hospital has quadrupled: "Previously, we had 250 boys a year who had attempted suicide, and now there are 1,000. Since 2013, there has been a continuous increase that skyrocketed with Covid, but it predates it because in 2019 we were at 400. There are more girls now, and they are younger. I have no doubt that screens are behind this. There is increasing evidence showing their negative effects."
Villar sees the "causality" in his "daily clinical practice," where he encounters "new sources of suffering, different from those that existed a decade ago." "Abuse within the family existed then and exists now, but cases like a 12-year-old girl attempting suicide because she has a 50-year-old boyfriend who pretended to be her age on social media and has been harassing her for months were not seen before."