Adding video gaming to the list of recognized behavioral addictions could help millions in need. It could also pathologize a normal behavior and create a new stigma.

Science fiction is replete with notions of losing oneself inside a digitally generated alternate reality. But for millions around the world, that dystopic vision could be very real.

Mounting neurological evidence suggests that video games may act like traditional substances of abuse. But some researchers remain unconvinced that gaming can constitute an “addiction.” Image courtesy of Shutterstock/eranicle.

Many governments already see excessive, compulsive playing of online video games, such as League of Legends and World of Warcraft, as a serious adolescent public health issue and have established treatment facilities, especially in China and South Korea (1). The adverse effects of teens’ “addiction” to the games are not just time lost studying or socializing with their peers. Some evidence associates video game addiction with depression, attention-deficit/hyperactivity disorder (ADHD), and obsessive-compulsive disorder (2). Whether there is a cause-and-effect relationship remains unclear.

As in the case of patients diagnosed with other addictions, so-called Internet Gaming Disorder (IGD) affects those around them, too: in extreme cases, it has reportedly resulted in household violence by children against their parents, who are trying to take away their games, according to Philip Tam, a psychiatrist with the not-for-profit Network for Internet Investigation and Research Australia in Sydney. “A lot of child psychologists say, we’ve got parents living in fear of their kids,” says Tam.

Whether video games can produce a true addiction in a clinical or scientific sense is still highly controversial. Can a game be considered an intoxicant? The neurological evidence is growing that games may act like traditional substances of abuse, with compelling similarities between the effects of drugs and of video games on the minds of users (2). But many worry that labeling teenagers “addicts” will pathologize behavior that is normal, and lead to false epidemics of other compulsive behaviors, such as sex and eating.

“I don’t know that there’s any consensus in this field right now,” says Nancy Petry, a professor of medicine at the University of Connecticut in Farmington, who was on the American Psychiatric Association committee that considered adding IGD to the latest diagnostic manual but decided to wait. “Personally, I think it really likely is a mental disorder, but I think we need to better quantify what it is we’re studying.”

Subtle Distinctions Throughout the 1970s and 1980s, the word “addiction” in a medical setting referred strictly to substances, such as alcohol, tobacco, and drugs, if it was used at all. Before 2013, “addiction” did not appear in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM), the working dictionary of mental health. Alcohol and substance abuse were simply called alcohol- or substance-related disorders, and a diagnosis hinged on the presence of symptoms such as craving, tolerance, and withdrawal. On the other hand, pathological gambling was considered an inability to resist impulses, along with disorders like pyromania (setting things on fire), kleptomania (compulsive stealing), and trichotillomania (compulsive hair-pulling). But over the past 15 years, the idea that it is possible to become addicted to a behavior has gained traction, especially after neuroimaging began to show that behaviors such as gambling could activate the brain’s reward system in the same way as drugs. “I think there are some people that are still holding out,” says Howard Shaffer, professor of psychiatry at Harvard Medical School in Boston, and director of the Division on Addiction at the Harvard-affiliated Cambridge Health Alliance. “But I think the evidence is pretty overwhelming now that all kinds of things can change neurochemistry. It simply doesn’t require the ingestion of drugs.” The DSM has begun to reflect that. The authors of DSM-5, released in 2013, created a category for “substance-related and addictive disorders” that included gambling disorder, the first behavioral addiction to appear in the same class as substance addictions (3). Video games were also considered for inclusion, but the working group decided there wasn’t enough evidence—yet (4). But the group did identify IGD in an appendix as worthy of more study and proposed a set of criteria for diagnosis. “I would say that it certainly merits exploration,” says George Koob, director of the National Institute on Alcohol Abuse and Alcoholism. Classification as a psychiatric diagnosis in the DSM requires clearing a very high bar, one in place to prevent the proliferation of mental disorders, Petry notes. “Certain things that were once considered mental disorders—like homosexuality—no longer are, and that’s a good thing.” Petry is one of many researchers who say that more data are needed to show both that IGD persists in patient’s lives and that it is a unique condition, not caused by preexisting, underlying mental health issues. “I don't think that body of research has made that clear,” says Chris Ferguson, a professor of psychology at Stetson University in DeLand, Florida. “Some people who are depressed stay in bed all day, but we wouldn’t say that they have a bed addiction.” Thousands of people attend the annual League of Legends video game world championship competition in person and millions more view it online. Image courtesy of Flickr/Chris Yunker.

Pathways of Addiction Arguments for video game addiction dovetail with the recent evolution in the concept of addiction itself: evidence that what causes the patient to lose control is not the substance itself, but the underlying neural circuitry that fires when presented with the reward the substance provides. At the center of this understanding of addiction is the brain’s reward system, in which using the substance triggers release of the neurotransmitter dopamine, which influences neurons in the nucleus accumbens, as well as other brain areas, such as the prefrontal cortex. Repeatedly activating these complex circuits modifies neural connections until these circuits respond to mere anticipation of the reward—as in Pavlovian conditioning—and produces the classic symptom of craving. Over time, the changes in dopamine receptors and the functioning of these pathways can diminish the sense of pleasure and produce tolerance. At the same time, dopamine exposure forges changes in other brain areas, such as the amygdala, and this can lead to a boost in negative emotions, such as fear and stress in the drug’s absence, leaving addicts seeking the drug simply to escape the pain of withdrawal. These changes in neural circuitry wrought by drug use persist, says Nora Volkow, director of the National Institute on Drug Abuse, and they go some way toward explaining why so many addicts relapse (5). This model treats addiction as a brain disease, not a moral failing. As with other diseases, individuals may be more or less prone to it based on a complex—and so far, largely undetermined—mix of genetic and environmental factors. Although the neurobiological approach does have its critics (6), proponents, including Volkow and Koob, suggest the model could explain addiction in general and its emotional side effects, leading to new medications to treat addiction, some of which are being tested (7). “In drugs, the person gets activated when they see that syringe or they see that dealer,” says Volkow. In video games, it may be the burst of speed from a successful trick or the cry of a defeated enemy. “It is exactly the same circuitry that gets involved,” she says. In 2001, a key study in Neuron led by Hans Breiter of Massachusetts General Hospital in Boston used fMRI to show that gambling could activate reward centers in the same way as a substance (8). Neuroimaging studies of video gamers are more recent, but show many similarities, Volkow adds. One 2011 fMRI study led by Simone Kühn, of Ghent University in Belgium, of 154 14-year-olds found that frequent gamers had more gray matter in the left ventral striatum, a change that may result from increased dopamine release that also shows up in those addicted to gambling (9). With video games, as with gambling, the intermittency of the reward only heightens its conditioning power. “You don’t know when you will be able to kill the adversary or find the treasure that the video game is offering—but there is that moment when you do,” says Volkow. “That becomes reinforced. Because it’s actually something that you did well, dopamine goes up and it keeps you going.” Nor does the challenge need to be especially complex or gory. “Candy Crush is a very interesting game,” Volkow offers, referring to the mobile game published by Activision Blizzard, in which players try to arrange a grid of brightly colored candies into rows and columns; align them in the right pattern and they disappear with a visual poof, a chime, and a cascade of new candies to take their places. Volkow recalls boarding a flight this summer: “I would say 30% of the plane was playing this Candy Crush. And they would have these little sounds and colors. So you get conditioned to that sound and the color, and those become reinforcing. And that’s exactly how our brain works.” Some developers take it even further, notes Philip Tam, with trained psychologists on staff to “tweak the gameplay, not make it too hard, to keep [players] in the zone” (10). In an influential 2001 article on the gaming industry website Gamasutra, then-psychology graduate student John Hopson deconstructed game design through the lens of behavioral psychology, introducing developers to language, such as “reinforcers” (game rewards: for example, advancing to higher levels or collecting new tokens or treasures) and “contingencies” (the game rules that govern when reinforcers are handed out) (11). Hopson presaged the increasingly complex rewards and achievement systems that nearly all big-budget games now implement, and that Hopson himself would later apply in games such as Destiny as a researcher for game studio Bungie (see www.gdcvault.com/play/1016539/Behavioral-Game). There is little to no research, however, on whether these specific awards systems contribute to cases of video game addiction. Another way in which games may provoke an addiction-like cycle is through the march of technology: as manufacturers and developers create more powerful equipment and deliver better graphics, gamers take part in more immersive and novel experiences, mirroring—intentionally or not—drug users seeking stronger and stronger substances. “Today’s World of Warcraft is tomorrow’s Pong,” says Shaffer.

Virtual Realities Concern about video game addiction is perhaps most prominent in east Asia, where many feel that games offer such a vivid alternative reality that young, developing brains are being altered in unprecedented ways by spending so much time there, and that these changes may be components of a new type of addiction. Tae Kyung Lee, a psychiatrist at Korea’s National Mental Health Center in Seoul, who oversees a government-funded treatment clinic for adolescent gamers (see Sidebar), bases his therapy around the observation that many of his patients who can’t control how long they play also have a disrupted sense of time in the game, implying a sort of virtual time warp. “Just 3 or 4 hours passes in real time, but they feel they have spent thousands of years finishing the game,” he says. Even when they’re not playing, many gamers also experience artifacts from virtual worlds—sounds, vision, or trained reactions—bleeding into the real world. In 2010, Angelica Ortiz de Gortari was a Master’s degree student in Stockholm researching internet addictions. “I’m no hardcore gamer,” she says, “but I used to play.” For research, she picked up Resident Evil, a survival horror series in which players fend off zombies and biological terrors. Then one day in a supermarket, she looked down the aisle at a distant item and found herself involuntarily trying to call up a virtual sniper scope to see further, just as she would in the game. Struck by her reaction, Ortiz de Gortari refocused her thesis to understand what had happened, which she refers to as game transfer phenomenon (GTP). In her interviews, she found that gamers reported a wide variety of examples of virtual worlds bleeding into real life. One person reported seeing floating health bars above their opponents while playing soccer; others said they felt their bodies begin to strafe from side-to-side as if controlled by a joystick. In a 2015 study of 2,362 gamers, Ortiz de Gortari, now at the University of Liège in Belgium, and her coauthors reported that 97% of the gamers reported having experienced GTP (12). And in a study published in 2016, she and her colleagues found that people with severe GTP are more likely to have problematic or addictive gaming habits (13). The connection is still tentative, says Ortiz de Gortari; it’s not clear that addiction and GTP share the same neurological pathways. Nevertheless, in 2015, the South Korean Ministry of Health and Welfare created a public service announcement urging gamers to look for signs of GTP in their lives as a marker of addiction (see https://www.youtube.com/watch?v=D7Suuxeqjo4). Ortiz de Gortari says new virtual reality gaming, for example with Oculus Rift and Sony PlayStation headsets, could lead to increased GTP and other cognitive and perceptual changes. But the intensity of the experience might push virtual reality gamers to shorter overall sessions, a sort of self-regulating effect.