Present at the Future by Ira Flatow Read Free Book Online Page B

Is the brain laying down the same kind of new pathways? Malenka says the general consensus among scientists is that “yes, a lot of these other kinds of compulsive, especially rewarding behaviors, or reinforcing behaviors like gambling, like overeating, like perhaps even video game playing, certainly effect these so-called reinforcement reward circuits, they do effect the release of this chemical messenger dopamine. Work done by Volkow and others has shown that it’s not only the release of dopamine but also how much is released and how fast it’s released that is important.
    “And it turns out, the highly addicting substances, like cocaine, can really cause a much more rapid, stronger increase in this chemical messenger than, for instance, what I do all the time, which is eatdoughnuts, or eat a quart of Häagen-Dazs ice cream, which is highly rewarding for me. But I can kick the habit when I choose to.”
    WATCHING THE CRAVING IN THE BRAIN
    Volkow agrees. She says it’s a “very interesting question that has started to intrigue many of the scientists; certainly, it has intrigued me for many years.” Using brain imaging, Volkow and her colleagues at the Brookhaven National Laboratory in Upton, New York, have watched the brain in action as it reacts to different stimuli, “specifically in pathological eating in obesity, versus those that we see in addiction.” And what she sees are both similarities and differences. The similarities: there is a marked disruption of the functioning of the dopamine system, which is directly affected by drugs, “but it’s also the one that motivates our behavior vis-à-vis natural activities like eating or doing social interactions or engaging in procreation—sexual behaviors.”
    The dopamine system becomes dysfunctional, she says, in both addiction and overeating. The dopamine is not released in as great a quantity as it was before, so that it does not produce that terrific sense of well-being—the high—as it used to. “And it is believed that one of the reasons why there is a motivation to either continue taking the drug or to compulsively eat is that it’s a mechanism to compensate for this deficit.” In other words, you eat more or take more drugs to stimulate more dopamine release. It takes more to achieve the “high.”
    On the other hand, what’s uniquely different in this case—eating versus drugs—in pathologically obese people “is that their brain is particularly sensitive to the pleasurable aspects associated with food. Evidently, that is the reason why they are favoring these particular stimuli—in this case, food—over other ones. So this is why some people become addicted specifically to a certain substance and others may become addicted to behavior, because each one of our brains responds with a different sensitivity to the rewarding effects of the stimuli.”

    THIS IS YOUR BRAIN UNDER STRESS…
    It’s well known that stress can make people relapse: I need that drink, just one bite of cheesecake. What link is there to addiction? “It turns out that the circuits in the brain that respond to stress,” says Malenka, “that release certain hormones in response to stress, are heavily interconnected with the exact circuits we’ve been talking about, the so-called reward circuits, the circuits that use dopamine. And work from many labs has shown that in humans as well as in animal models of addiction, stress is a very important factor in causing the continued use of a substance, as well as leading to relapse.” It appears that “the brain’s response to stress is actually pretty similar, under certain cases, to the brain’s response to certain drugs of abuse.”
    For example, in a classic set of experiments it’s been shown that “if you train an animal to self-administer a drug—this happens in human beings too—and then you take the drug away for many weeks or months, an acute stressful event can have that person or animal start using the drug