It’s good that we’re learning more and more about the brain’s reward systems. I’ve spent months dissecting their role in hunger—and indeed, hunger is the subject of my upcoming AHS 2012 presentation!

(This is part VII of a series. Go back to Part I, Part II, Part III, Part IV, Part V, Part VI, or Part VII.)

Unfortunately, one side-effect of more brain science is more breathlessly ominous news releases claiming that the Vice of the Moment—whatever it is this week—is mediated by the same brain circuits that mediate drug addiction! EVERYONE FREAK OUT

“After a month of sugar binging and increased dopamine levels, the rats’ brains developed fewer dopamine receptors and more opioid receptors—changes similar to those observed in mice on cocaine and heroine.”
–Move Over, Heroin: “Sugar Addiction” May Be a Reality

“In a new study of mouse brains, scientists show that the patterns of gene regulation stimulated by salt cravings are the same gene patterns regulated by drug addiction.”
–Cocaine Addiction Uses Same Brain Paths as Salt Cravings

“People who frequently use tanning beds experience changes in brain activity during their tanning sessions that mimic the patterns of drug addiction, new research shows.”
–How Tanning Changes The Brain

    “Oh, no!” we think. “Eating sugar, or getting a tan, is just like being a junkie! Who will rescue us from the evil clutches of Toucan Sam and Cap’n Crunch? Or the siren song of the tanning bed?”
    “Oh, yes!” the regulators think. “We can politicize this issue by stigmatizing people as ‘addicts’, taxing and criminalizing their behavior, and using the profits to finance the same efficient and effective tactics* we’re using to fight the War on Drugs!”

(* = sarcasm)

Anyway, I don’t want to turn this into a political rant. OK, maybe I do, a little, having just paid my taxes, and having seen this incredible sentence in a peer-reviewed scientific paper:

Arch Dermatol vol 141, Aug 2005 pp. 963-966
UV Light Tanning as a Type of Substance-Related Disorder
Molly M. Warthan, MD; Tatsuo Uchida, MS; Richard F. Wagner, Jr, MD

“…Even if the issue of indoor UVL exposure is successfully addressed, the successful regulation of outdoor tanning with natural sunlight, a major source of UV exposure, would remain problematic.”

Yes, our self-appointed guardians of public health are sincerely disappointed that they haven’t yet found a way to make the sun illegal.

OK, I’m done.

The Role And Limits Of Reward

Given the fearmongering in the popular press, and the ongoing confusion in the paleo community, I want to emphasize two important points about the role and limits of reward. The first I’ve mentioned before, but I’ll mention it again, because it’s important:

• Any time we experience pleasure—any time we “like” something—that’s hedonic impact. (And it doesn’t require conscious appreciation of the fact.)
• Any experience we “like” is capable of producing a “want” for more—incentive salience.

Organizing the refrigerator. Petting a dog. A long shower after hard physical work. Greeting a friend or a lover. Being complimented. Successfully finishing a long, difficult task. Seeing wildlife outside your window. It doesn’t matter whether that pleasure is from a physical thrill, positive social interaction, the satisfaction of a job well done, or direct chemical stimulation—it’s all mediated by (gasp!) the same circuits that mediate drug addiction.

This is why drugs that act on the reward system are so addicting: they can directly stimulate the feeling of having done something pleasurable without the user having to actually do anything.

And it’s very likely that we find pleasure in these actions for a reason: they were survival traits throughout evolutionary time. Stated in scientific language:

Proceedings of the National Academy of Sciences, July 11, 2011
Relation of addiction genes to hypothalamic gene changes subserving genesis and gratification of a classic instinct, sodium appetite
Wolfgang B. Liedtke, Michael J. McKinley, Lesley L. Walker, Hao Zhang, Andreas R. Pfenning, John Drago, Sarah J. Hochendoner, Donald L. Hilton, Andrew J. Lawrence, Derek A. Denton

“Drugs causing pleasure and addiction are comparatively recent and likely reflect usurping of evolutionary ancient systems with high survival value by the gratification of contemporary hedonic indulgences.”

Therefore, saying that sugar, salt, tanning, or any other Vice Of The Moment “mimics the patterns of drug addiction” creates needless fear and distress, because it’s a tautology—it’s always true. It’s like saying “Did you know that your body is contaminated with DIHYDROGEN MONOXIDE?” Well, yes: that would be one name for ‘water’. (Read the Dihydrogen Monoxide FAQ for more information on this dangerous chemical.)

It’s also useful to remember that “addiction” is a matter of definitions and social norms. Even a behavior generally viewed as positive (e.g. cleanliness) is defined as pathological (obsessive-compulsive disorder) when practiced too frequently.

The second important point is easy to forget in the excitement of learning:

I offer the following analogy: the reward system is like the dashboard of a car.

As the driver of the car, we know some basic things just by sitting in the driver’s seat: is it running? Is the engine making a strange noise? Does it respond to our use of the steering wheel, gas, and brake? However, there is a lot we can’t know from direct sensory input, and the dashboard (with its associated gauges and warning lights) is how the car lets us know important things like coolant temperature, oil level, our exact speed, and how much gas is in the tank.

Continuing the analogy, if the gas gauge reads “empty”, the problem might not be that the gas gauge is faulty. We might actually be running out of gas! Similarly, if the coolant temperature keeps reading high, we shouldn’t just blame the gauge, or the temperature sensor, and keep driving. (“You’re fat because you lack the willpower to stick to a diet”…”everyone is fat primarily because they are trying to entertain themselves with food”…does this sound familiar?) The fact that we learn of a malfunction through the dashboard does not mean that a malfunctioning dashboard is the cause of our car troubles!

Similarly, just because we have a problem (for example, excessive hunger) that manifests itself through the reward system (e.g. “wanting” so much food that we start gaining fat), that doesn’t mean that a dysfunctional reward system is the cause of our hunger! We could have any number of metabolic, endocrine, or nutritional issues to which excessive hunger is a perfectly reasonable response. (A few examples: diabetes, hypothyroidism, vitamin insufficiency, some antidepressant and antipsychotic drugs.)

It’s tempting to explain away every aspect of a mind-bogglingly complex homeostatic system, like human metabolism, in terms of the few parts we understand. The result even looks like science, because of all the footnotes! However, I’ve found the temptation is best resisted.

Conclusion

• The brain’s reward system underlies all our motivations—not just the bad or “addictive” ones. Any choice we make that isn’t purely a rational product of our forebrain likely involves some measure of reward signaling.
• Just because a behavior we hope to change is signaled through the reward system doesn’t mean that it’s caused by a malfunction in the reward system. The reward system is the conduit by which our wants and needs are communicated to our conscious mind: it’s not the cause of our wants and needs.

I hope this article helps clarify the role and limits of reward!

Live in freedom, live in beauty.

JS

(To be continued! Or, go back to Part I, Part II, Part III, Part IV, Part V, Part VI, or Part VII.)

I’ve added a couple more books to my Recommended Reading list. As always, you can support gnolls.org at no cost to you by buying them (or anything else) through my Amazon referral links…

…and if you’ve ever wondered why this site is named gnolls.org, you need a copy of The Gnoll Credo. (Glowing reviews, signed copies, Amazon, B&N, international sales.)