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In 2011, the American Society of Addiction Medicine redefined addiction as “a chronic disease of brain reward, motivation, memory, and related circuitry.” Nora Volkow, an eminent neuroscientist, psychiatrist, and director of the National Institute on Drug Abuse, is the leading researcher in the area of the addicted brain. The great-granddaughter of Leon Trotsky, Volkow is making her own mark on history with more than a decade of peer-reviewed research suggesting that addictive behaviors become compulsive because the brain’s control mechanism is disrupted. Here is what is happening in the addicted brain.

Salience and Reward

Salience is the relative importance of an object or behavior, and reward is the pleasurable feelings we derive from that object or behavior. Salience and reward are closely linked in the addicted brain. Addictive substances and behaviors are extremely high in salience to addicts, which means they focus their attention on them. When addicted people engage in addictive behavior, the nucleus accumbens, located deep within the brain, releases a big hit of dopamine, the reward neurotransmitter. Eating a chocolate bar gives you a little squirt of dopamine; eating a hot fudge sundae with cookies ’n’ cream ice cream, whipped cream, sprinkles, and nuts delivers a heftier dose of the neurotransmitter. And taking a drug like heroin causes a huge surge of dopamine. The reward that an addict gets from the dopamine gives that activity great salience, making it their singular focus.

Memory

People who have addictions remember the salience of the activity because the event is registered in both the amygdala and hippocampus. The brain’s emotional center, the amygdala, registers the intense salience and reward and locks it into the memory bank, the hippocampus.

Drive

Drive is what motivates addicts to continue in their behavior. It pushes them to repeat the behavior again and again. Drive originates in the orbitofrontal cortex (OFC) and the anterior cingulate gyrus (ACG), brain regions often associated with working memory. Further research is necessary to determine the degree to which working memory is involved in drive. What happens when an addict craves a drug, is that their OFC and ACG become hyperactive and boost drive intensely. If working memory is involved in drive, it may be like a broken record, replaying the desire to procure the reward, over and over. Indeed, these regions of an addict’s brain resemble those of people suffering from obsessive-compulsive disorders.

(Out of) Control

The control aspect in this process is located in the PFC, the home of working memory. For nonaddicts, the PFC helps them resist harmful behavior. For example, when you put your hand over the top of the wine glass rather than accepting another glass, your PFC has been activated to make that decision. But in the addict’s brain, this behavior is reversed: when a person is engaged in the addictive behavior, the PFC is turned down to low. As you would expect, this diminished activity is associated with less self-monitoring and behavioral control. It’s as if the Conductor has left the stage. The salience of how good the addictive substance or activity feels overrides the PFC’s ability to rein in the behavior. When an addicted person craves something, as opposed to being engaged in the behavior or using the substance, the PFC increases in activation. While the person is craving, the PFC recruits working memory to bring up the past memories of the salience and reward, as well as to strategize how to satisfy the urge. In the addicted brain, the working memory Conductor, which should be in control, is under the control of the addiction.

The Addiction Process

In the addicted brain, working memory is recruited as a key component of the addictive process, helping to satisfy the addiction rather than inhibiting it. For illustrative purposes, this image shows the addictive process linearly, though the various stages may not always occur in this sequence.

We got a firsthand glimpse into obsessive behavior when Ross bought a really cool first-person video game about a week before Christmas in 2003. During the day, Ross was a mild-mannered academic, but at night he morphed into an ex–Navy SEAL working in the top-secret Third Echelon subbranch of the National Security Agency. Ross was entrusted with saving the United States from a breakout war with China. He used his stealth and considerable military acumen to stalk enemies and infiltrate their headquarters, even rescuing the United States from the detonation of a nuclear bomb.

You would think Tracy would have been proud of all his hard work and his determination to see the mission through. But in spite of the fact that Ross had single-handedly prevented World War III, she was concerned that he was spending too much time in this fantasy world. He did, after all, skip all of his favorite Christmas activities: going to the German Christmas market in Edinburgh with its steaming mugs of glühwein, hiking in the snow, making Christmas cookies and candy, and caroling on Christmas Eve. The video game had turned Ross into a veritable Christmas Grinch.

For Christmas Day, Tracy banned him from playing. And although Ross found himself moping about and fretting nonstop about what might happen if the game’s shadowy criminal activated the nuclear device while he was celebrating the holiday, he realized that maybe Tracy was right: he had fallen into the grips of video game obsession. He snapped the disc in two and swore off video gaming for good, a pledge yet unbroken.

A lot of gamers are able to moderate the siren call of really awesome video games and do other things aside from assaulting the Sith Lord, winning the Grand Prix, or building a new civilization. But research shows that one in ten video gamers nationwide exhibit signs of addictive behavior. The web is full of stories from gamers who have become obsessed to the detriment of their work and relationships. Consider the following confession posted on a gaming website about addiction to a popular online game:

I had a wife, 3 houses, 3 cars, money in the bank. I stopped working. I went through a divorce. I had to sell a house. I had to sell a car. I have nothing in my bank account now, but good thing my game account is paid in full a year in advance. My credit is in ruins. I don’t care.

Marriages are ruined, children neglected, and financial futures destroyed. The Chinese government’s deep concern about the negative effect of Internet gaming addiction on many of its citizens may have been behind its ban of the popular online game World of Warcraft (WoW) in 2009.

That same year, a group of Taiwanese researchers led by Wei-Chen Lin undertook a groundbreaking study to discover what was happening in the brains of gaming addicts when anticipating a chance to play. They recruited ten heavy users of WoW who had made it to the top levels of the game by regularly playing over thirty hours a week. They also recruited ten nongamers who used the Internet less than two hours a day.

The researchers put them in an fMRI scanner and showed them a series of pictures, alternating between a neutral image and a WoW game image. It is important to note that they did not scan the participants while playing the game. They showed them pictures because they wanted to trigger a craving response in the brain.

As expected, the scans of the nongamer brains showed no difference between WoW images and the neutral images. When the WoW gamers saw the neutral images, their brains looked much like those of the nongamers. But when they saw the game images, the fMRI display screens lit up like a Christmas tree.

 The nucleus accumbens activated, anticipating the dopamine hit that came from playing the game—for example, when their character completed a quest, saved a friend, or slew a foe.

 The PFC powered up and put working memory to work to figure out how to get that dopamine hit by executing a plan to play the game.

The fact that this study looked at the brain activity when the participants were craving the addictive behavior as opposed to engaging in it explains why the PFC lit up. As we described earlier in the addicted brain model, craving changes the way the PFC and working memory function. The PFC and working memory, which moderate and control behavior in the nonaddicted brain, were in fact recruited in the craving process, enabling it, and finding a way to get that dopamine hit. When it comes to fulfilling a craving for an addictive substance or behavior, working memory becomes an enemy rather than a friend.