Research made national news this week that the cookies are more addictive than psychoactive drugs. That claim may be exaggerated, but the neuroscience of junk food addiction is nonetheless fascinating and relevant—mentally, physically, and socially.
"Nothing gets me high as that sandwich cookie does. But I love the filling most. I rub it on my roast, mix it in with my coffee, and spread it on my toast. I love the white stuff, baby. In the middle of an Oreo."
—Al Yankovic, "The White Stuff," 1992
The rat stands in a plastic maze. At the end are two rooms, each decorated in its own unmistakably unique, gaudy fashion. The rat knows them both. Inside one room, he has received injections of morphine or cocaine. In the other, he's gotten injections of a saline placebo. The rat has learned to prefer the drug room.
He even chooses to lounge in the drug room after the injection supplies have dried up. It's kind of like how you might hang out in the parking lot outside of an old high school, remembering the glory days; or at the apartment of an ex-lover, befriending the new tenants. Your ex-lover is dead, but it still feels good.
This is a paradigm called conditioned place preference. It's a standard behavioral model used to study the Pavlovian rewarding and aversive effects of drugs. Dr. Joseph Schroeder's rats are not pioneers.
Schroeder is an associate professor of psychology and director of the behavioral neuroscience program at Connecticut College. Last year, Jamie Honohan was a senior student researcher in Schroeder's lab and scholar in the college's Holleran Center, which focuses on social justice issues, public policy, and community action. Honohan was interested in the obesity epidemic—specifically, why there is more obesity in urban, low-socioeconomic-status populations, and the role of a lack of nutritious food.
So Honohan came to Schroeder with an idea for some research based on the rat conditioning model. What's a thing that both rats and humans like? Sewers, tunneling, hammocks, ... Oreos. That's it. Oreos are also cheap calories, widely available, and contribute to the obesity epidemic. Would feeding Oreos to the rats in this model have the same conditioning effect as giving them drugs?
Honohan, Schroeder, and some other students designed an experiment. In terms of behavior, the Oreos did it. The rats trained with Oreos spent just as much time in the Oreo room—as opposed to a boring rice-cake room, even after there were no Oreos or rice cakes—as did the rats trained with cocaine or morphine.
Then the researchers went a step further.
What if we cut open their brains, too, they wondered.
"We examined the nucleus accumbens," Schroeder explained to me, "which is the brain’s pleasure center. We measured the expression of a protein there [c-Fos]. So it basically tells whether that brain center is being turned on or not in response to a behavior. And we found that there was a greater number of neurons that were activated in the brain’s pleasure center in animals that were conditioned to Oreos compared to animals that were conditioned to cocaine [or morphine]."
"What that indicates," Schroeder says, "is that, perhaps, high-fat, high-sugar foods are stimulating the brains in the same way as drugs of abuse and can be considered as a potentially addictive substance."
That concept has been shown before, but remains important. In a 2010 study published in Nature Neuroscience, rats who spent 40 days eating bacon, sausage, cheesecake, and frosting—someone please market that combination; I mean please don't—became "addicted." They continued eating even in the face of electrical shocks. Non-addict rats did not. The researchers, at Scripps Research Institute in Florida, likened the brain activity in the addict rats to that of cocaine and heroin addicts.
"We make our food very similar to cocaine now," commented an unmoved Dr. Gene-Jack Wang at the time. Wang is a biomedical imaging researcher at Brookhaven National Laboratory. "[Now] we purify our food," he said. "Our ancestors ate whole grains, but we're eating white bread. American Indians ate corn; we eat corn syrup."
Wang also drew an interesting parallel between the social roles of processed food and cocaine. People have chewed coca leaves for 4,000 years, but the pure cocaine alkaloid was not isolated until the mid-19th century. It was more potent and addictive. American manufacturers were quick to put it in everyday products.
Like junk food, the ubiquitous coca extract products came to be most notoriously abused among underprivileged populations. Civil unrest and white panic around "negro cocaine fiends" at the end of the 19th century played a role in the removal of the alkaloid from Coca-Cola and its criminalization shortly thereafter. A century later, the still more potent, cheaper crack cocaine hit ghettos so disproportionately that African-American leaders like California representative Maxine Waters called for a Department of Justice investigation into the possibility that the drug's introduction was a CIA plot against inner-city black Americans.
The plot this time, according to journalist Michael Moss in Salt Sugar Fat (among others) has been squarely attributed to a manipulative food industry—companies like Nabisco, Kraft, General Mills, Mars, etc.—formulating products that play on "the hidden power of some processed foods to make people feel hungrier still."
Dana Smith is a doctoral candidate in the department of psychology at the University of Cambridge. She told me that while the junk food-cocaine analogy seems valid, her concern about the publicity around Schroeder's research this week is that media outlets—including NBC, CBS, ABC, Forbes, The Los Angeles Times, Chicago Tribune, and Gawker—have said Oreos are as or more addictive than cocaine.
"This study did not offer rats a choice between Oreos and cocaine," Smith said. So that conclusion is not a valid one.
“The data is so overwhelming the field has to accept it,” said Nora Volkow, director of the National Institute on Drug Abuse, in 2011. “We are finding tremendous overlap between drugs in the brain and food in the brain.”
The response at the time from American Beverage Association consultant Richard Adamson is emblematic of the industry position: denial and underplaying that junk food is addictive. “I have never heard of anyone robbing a bank to get money to buy a candy bar or ice cream or pop.”
Schroeder will fly to San Diego next month to present the Oreo rat study at the conference of the Society for Neuroscience. His findings do not constitute a novel idea, and some news bits about it may be hyperbolic, but the comparison between junk food and cocaine is in ways apt and important. The obesity message warrants continued hammering, as the epidemic costs the United States around $147 billion every year. (See: The average man's body.)
The idea of the food desert—that sometimes the only place to get food in your neighborhood is a 7-11—still hasn't landed with people who see obesity, like drug abuse, solely as the province of weak will. There is a web of educational and social factors to consider. This week's study and news cycle brings these ideas back into the conversation. Valid public health awareness can be born of exaggerated headlines on Facebook walls.
It's when we get into discussions of social justice and scale of abuse that the effects of junk food and recreational drugs can begin to be compared. “Even though we associate significant health hazards in taking drugs like cocaine and morphine," Honohan said, "high-fat/high-sugar foods may present even more of a danger because of their accessibility and affordability."
Finally and inevitably, there is the note that this study is an animal model. We are not rats. At the end of the day, though, we both love hammocks. And, Honohan noticed, just like so many humans confronted with an Oreo: Many rats “would break it open and eat the middle first.”