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Imagine a website that reviewed narcotics. Imagine that people who were really into methamphetamine or heroin could go to one of dozens of sites to weigh the pros and cons of each drug. Imagine these sites specifically targeted kids. What would the reviews on a site like this sound like? Perhaps a little like this?“The drugs here are addictive beyond reason, making us yearn for one more hit, one more shot, or one more snort. No matter what time it is, no matter where we&#x27;re supposed to be or what we&#x27;re supposed to be doing, these drugs can keep us in our chairs for days at a time, locked away with our pipes and needles just tripping the hours away. Addiction in drug form awaits those who read this list.”
 

 
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 This is the text from an actual game reviewing website, except with drug terms switched for the gaming ones. In the world of gaming and other screen-based media, addiction isn’t a warning—it’s a selling point. The most addictive apps are the ones you have to get. Binging on whiskey every weekend is very unhealthy, but binging on “<a href="https://www.epicgames.com/fortnite/en-US/buy-now/battle-royale">Fortnite</a>”? Ah, that’s just good fun.Or is it? A new field of research is suggesting that age-old concerns about the detrimental effects of screen time might be well-founded. It turns out that video games and other entertainment might not be as different from <a href="https://www.pbs.org/wgbh/nova/video/addiction/">drug use</a> as you think.<h2>The link between screens and addiction</h2><a href="https://www.npr.org/sections/health-shots/2017/08/09/542215646/video-games-may-affect-the-brain-differently-depending-on-what-you-play">Worries about TV and video games rotting your brain</a> have been around as long as TV and video games. Overall, the evidence has been mixed as to how valid these concerns are. There is some evidence that screen usage contributes to attention deficit disorders, but it’s hard to study something as variable as the notion of screen time. Does typing a Word document count? How about talking to your grandmother on Facetime?“The definition of the word ‘screen’ has evolved considerably,” says Dimitri Christakis, a psychology professor at the University of Washington and director of a children’s center at Seattle Children’s Hospital. “To the point where it’s almost a meaningless construct.” Christakis’s work separates media consumption by pace and violence. He’s found that viewing high-paced, violent entertainment in the first few years of life is strongly associated with ADD and ADHD by age seven.Scientists have seen links between screens and attention problems before, but the effects are hard to understand. Some say that media simply replaces more beneficial activities. Others say that children become desensitized to its speed or violence and crave even more. Christakis frames media use as a resetting of the brain’s internal clock. It’s not clear if this effect is different when applied to video games versus television, but by focusing on the pace of media—rather than the type—his team sees a much more straightforward connection.Of course, you can’t ethically test these ideas in humans, so Christakis and his team came up with an experiment in which mice pups are raised alongside near-constant stimulation. He takes a baby mouse and, for 42 days, plays audio from a number of dizzying cartoons, like “Pokémon” or “The Powerpuff Girls,” and shows flashing lights that catch their attention without upsetting them. Then he runs them through a series of tests and mazes. The results show they are now less able than normal mice to pay attention to new objects and remember things.
 

 
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 Then, in 2016, he added a new twist to the mix: cocaine. By giving cocaine to the mice and then looking at their brains, he saw surprising connections between drug use and overstimulation. For instance, the over-stimulated mice that had cocaine were more tolerant of the drug, wanted more of it—in that they went back to it when given the choice—and were more hyperactive. But even more than that, the mouse brains looked a lot like human drug users’ brains—namely, in the networks that manage the release of a chemical called glutamate.“You can think of them, from a layman’s perspective, as a ‘Go’ signal,” says Susan Ferguson, a neurologist and addiction expert who co-wrote the study.Glutamate is released when the brain creates new connections between regions and is important for a number of brain functions, including learning and plasticity. When it comes to drug use, some of those connections might increase the pleasure of a drug and some might decrease it, making the brain crave more. Both can heighten addiction. In chronic drug users, those networks seem to be on a hair trigger—meaning they are constantly ready to create new connections. Ferguson says that the over-stimulated mice brains looked more like those of chronic drug users than the normal mice that got cocaine, especially in the connections between the decision-making pre-frontal cortex and the reward-regulating striatum.Mouse addiction isn’t a perfect analogue for human addiction, but the implications are still frightening. First, certain types of fast-paced media might be truly addictive. Second, overstimulation and screen addiction might lead to other types of addiction. And lastly, screen addiction might make permanent changes in the brain.
 

 
 

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 Certain types of fast-paced media might be truly addictive.
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 It’s not the first time someone has linked screen time to addiction (though it is the first time anyone has looked at the underlying physiology in animals). Most notably, in 2014, the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) added “internet gaming disorder”—which includes symptoms of addiction to gaming—to its appendix, meaning it soon might be a diagnosable disorder.But many experts and clinicians have complained that the description is just too vague and it’s not clear where the line is. In fact, addiction of any kind can be hard to spot. Loosely speaking, psychologists say addiction a) requires sufferers to feel a compulsion to do the activity, b) get withdrawals if they don’t, c) abandon other activities to do it, d) be aware it’s hurting them and still continue it, and d) perhaps even build up a tolerance to it. Screen addiction can fit these descriptions, and when it’s bad, it can destroy lives.“In my clinic I’ve had seen pre-adolescents and adolescents where the parent has tried to take away their video gaming console and they have had an outburst that destroyed the house,” says Christopher Hammond, a psychologist and researcher with Johns Hopkins University. “I’ve had teens where their phones were taken away and, as a reaction, the teen has made a suicide attempt.”Like many experts, Hammond doesn’t like the vagueness of the DSM-5 definition, but says it is crucial to recognize that something is going on in these kids. He says that from his work, it’s clear that drug addiction, gaming addiction, and ADHD all share a relationship to regions in the pre-frontal cortex and the striatum involved with reward processing.It’s similar to what Ferguson saw in the mice (though Hammond has not looked at that study seriously). The primary difference between drug addiction and screen addiction in the brain seems to be that, in the former, the reward is triggered by an outside chemical and, in the latter, by the brain itself. She says the trick to a really addictive game is that it continually allows you to become incrementally better, improving and thus triggering a rewarding dopamine release—to the point where the brain’s own reward becomes all-consuming. The brain gets addicted to its own chemicals.Interestingly, it’s not that different from what many experts say happens in drug addiction. Yes, the drug provides a high, but the addiction comes from the brain itself. Plenty of people do drugs without becoming addicted, just as lots of people use screens without craving those dopamine hits.It’s hard to know exactly how this plays out in the brain, and it gets complicated quickly. Just as with the mice, in some cases, a substance user gets more enjoyment from drugs than other people (often called sensitization). In others, they get less (referred to as tolerance). Most drugs create a mix of the two. Opioid painkillers, for example, create tolerance to their pain-killing effects while sensitizing cardiac function. Thus a patient needs ever more drugs to numb the pain but ever fewer to slow their heart rate and breathing. The combination can be deadly.Both of these effects were also present in the over-stimulated mice. Studies suggest that all of these changes can cause long-term damage to the brain’s ability to create new connections. Brain plasticity—the ability to build new networks and learn new things—may not be an infinite resource. Some research suggests that when glutamate builds too many networks related to drugs, it limits the networks involved in other types of learning. And the earlier addiction happens, the worse it tends to be.
 <figure class="richtext-image full-width"><img alt="grand-theft-auto_1920x1080.jpg" class="richtext-image full-width" height="450" width="800"
 src="https://www.pbs.org/wgbh/nova/media/images/grand-theft-auto_1920x1080.width-800.jpg"/><figcaption>A screenshot from a scene in the video game &quot;Grand Theft Auto&quot; Photo credit: <a href="https://www.flickr.com/photos/videogamephotography/16219539616">Videogame Photography / Flickr (CC BY 2.0)</a><div class="credit"></div></figcaption>
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 It’s clear that screen-addicted brains look a lot like drug-addicted brains in mice. And it’s likely that the former leads to the latter. But is an obsession with “Grand Theft Auto” or watching 20 straight hours of “Riverdale” truly an addiction? Isn’t that just cheapening the word? Here the answers are fuzzier.“The word ‘addiction’ is part of the controversy—it’s a very charged word,” Hammond says. “How do you compare someone who compulsively plays video games or uses their screen devices 10, 12 hours a day to someone who is using marijuana on a daily basis or perhaps using heroin?”Many psychologists have argued that using the word for what amounts to a bad habit—no matter how destructive it may be to someone’s life—minimizes the experience of chronic drug users who already have trouble making society treat their illness seriously. Others say we need to hold screen addiction to the same high standards we use for, say, alcoholism.
 

 
 

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 Some say we need to hold screen addiction to the same high standards we use for, say, alcoholism.
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 “I certainly believe that things like video games, social media, gambling, et cetera, can be genuinely addictive,” says Mark Griffiths, a behavior addiction professor at Nottingham Trent University. “[But] by my definition, very few people are genuinely addicted to video games or are genuinely addicted to social media.”Griffiths was a key voice in helping the World Health Organization recognize gaming addictions and agrees it’s serious. But he worries it’s being oversold. In a rare nationally representative survey on the subject, he and others found that 4% of adolescents are at risk for gaming addiction, which is four times the rate for gambling addiction. But he says the actual number of addicted gamers is far lower, perhaps just half a percent. If the real numbers were higher than gambling, you’d expect to see more people seeking help from addiction groups and doctors. True addiction wreaks havoc on people’s lives.“Healthy enthusiasms add to life and addictions take away from it,” he says. “Addiction is something that just completely compromises everything you do in your life.”There is one place where he agrees with the UW team. The key to any behavioral addiction is the pace. Faster gratification is more addictive. Slot machines are far more addictive than playing the lottery because the dopamine hit is so fast. A “World of Warcraft” game that takes days or weeks to explore and understand is less addictive than “Candy Crush,” with its constant gratification. Similarly, the problem with social media isn’t the screen, it’s the pace at which we are seeing messages.
 

 
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 This is the key thing for parents to remember. It’s not the amount of screen time that’s important as much as the type. Hyper-fast or violent content—whether it’s games or cartoons or even social media—offer more rewards to the brain and are thus more potentially addictive. Look for shows that are educational and take their time.Second, there may be a few crucial windows early in life where addiction can set in—especially in kids under two. But drug addiction tends to be stronger the earlier you are exposed, so caution is the best principle. And if you are worried that your kid might be spending too much time with fast-paced media, find another outlet for them in the real world that’s social and at which they can excel.Christakis agrees but sees a much more worrying picture. Unlike gambling or drugs, screens are ubiquitous and are even being given to babies (though the American Academy of Pediatrics <a href="https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/American-Academy-of-Pediatrics-Announces-New-Recommendations-for-Childrens-Media-Use.aspx">recommends</a> avoiding screens altogether—other than video chatting—for children younger than 18 months). In his latest work he’s seen signs of what he considers addiction in children as young as two. And regardless of whether you are comfortable with the word, he says, we have to be more vigilant of what kinds of media developing minds encounter.

New research shows that age-old concerns about the detrimental effects of screen time hold true.

Erik Vance

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