Is Food Addictive?

By Neuroskeptic | March 11, 2013 12:20 pm

Can food be addictive? Is obesity sometimes a form of substance abuse?

 

In a new paper, neuroscientist and Director of the National Institute on Drug Abuse, Nora Volkow, muses on ‘The Addictive Dimensionality of Obesity’

Volkow and her coauthors start out with a disclaimer – “we do not claim that obesity is the result of food addiction” – but despite this, they go on to argue that the two conditions have an awful lot in common. The key to both afflictions, we’re told, is the neurotransmitter dopamine

The phenomenological and neurobiological overlaps between obesity and addiction can be predicted on the basis that drugs of abuse tap into the same neuronal mechanisms that modulate the motivation and drive to seek and consume food… brain dopamine pathways play central roles in obesity and also in addiction…

It’s dopamine that makes both drugs and food fun –

Drugs of abuse work by activating the dopamine reward circuit, which, if chronic, in vulnerable individuals, can result in addiction. Certain foods, particularly those rich in sugars and fat, are also potently rewarding and can trigger addictive like behaviors in laboratory animals and humans… [likewise] the ingestion of palatable food releases dopamine in the striatum, in proportion to the ratings of meal pleasantness, and activates reward circuitry.

But there can be too much of a good thing. Overindulgence makes the dopamine, and the enjoyment, wear off. Users then consume more and more, to chase the high –

Both addicted and obese subjects [compared to non-addicts / to thin people] exhibit less activation of reward circuits when given the drug or the palatable food, respectively… it was suggested that blunted dopamine activation by consumption (of drug or food) could trigger overconsumption to compensate for the blunted response of the reward circuit.

And it goes on in this vein. Volkow et al’s is a good paper as far as it goes. It’s an interesting and accessible review of the relevant literature. The dopamine theory of addiction is extremely popular today, and this article is a fine statement of it. Leaving aside the question of how true this is, what worries me is the implications of this idea.

If you view addiction as essentially about reward (pleasure), surely that means that anything pleasurable could also be addictive? Or to put it another way, if you’re saying that addiction is the direct consequence of over-indulgence in a reward, then aren’t you saying that reward itself is ultimately what’s addictive?

After all, drugs and food aren’t the only rewarding things. Indeed, according to Volkow et al, everything good in life is a reward and they all act on dopamine. Here’s what the authors call a ‘bow-tie diagram’ which I think is a nice illustration of their approach (and its limitations):

If everything from food to friends to music are rewarding because they trigger dopamine release, then surely all of those things could be ‘addictive’. If ‘reward’ is essentially monolithic, and the various kinds of rewards differ only in how powerful they are, then everything’s addictive to a degree. The more fun, the more (potentially) addictive. The better something is, the worse it is.

This seems to me to be the logical conclusion of this approach to addiction. Let’s call this (very widespread) approach neuropuritanism.

The funny thing is that this idea – for all its medical, neurobiological, scientific language – actually undermines the concept of addiction as a ‘disease’ and reduces it to what amounts to a moralfailing – it casts addiction as over-indulgence. The Sin of Gluttony, if you will.

ResearchBlogging.orgVolkow ND, Wang GJ, Tomasi D, & Baler RD (2013). The Addictive Dimensionality of Obesity. Biological psychiatry PMID: 23374642

CATEGORIZED UNDER: Uncategorized
  • aneon

    Your sentence “The better something is, the worse it is” is very biased and surely not the logical conclusion, which is “The better something is, the worse it is potentially”. This “potentially” is the most important word here, as it draws the line between health and disease. Leaving it out seems somewhat dishonest…

    To go further, we all agree that this theory is very simple: greater pleasure => (greater reward greater dopamine) => greater risk of addiction. Too simple ? mmh maybe. But by calling the tenants of this neuroscientific theory “neuropuritanists” (which sounds like a moral judgment in itself, btw), you completely miss the point. You need scientific arguments to convince people that this theory is false, nothing else…

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Thanks for the comment.

      It’s true that anything addictive is only ‘potentially’ harmful, but if we accept that pleasurable = addictive, that would imply that the more addictive something is, the more tempted people would be to indulge to excess, and therefore to make the potential harm into an actual harm. So in fact the ‘potentially’ is redundant because the more rewarding/addictive something is, the less likely it is to remain only a potential harm.

      On the second bit, I never said it was true or false – but it is somewhat puritanical.

      • aneon

        Thank you for you reply and for the blog, as I have been reading you for long time with renewed pleasure each time – but without addiction, or so I hope ;)

        I wasn’t clear enough: I wanted to highlight the potentiality of the addiction, not the potential harm caused by an established addiction. Most of us won’t fall addict only because something is very pleasurable, but persons with addictive personalities may be far more prone to become dependent of wonderful things rather than just-decent things… In my opinion, the right way to understand this widespread theory we are discussing is to state that addiction is a risk, and never a fatality; and the amount of pleasure is only one of the associated risk factors (among the personality type, history, you-name-it, …). Am I a neuro-puritan for believing this may have some valid neurological grounds ?

  • http://twitter.com/Dave__M Dave

    The notion of reward as a synonym for pleasure is, some would argue, untenable. Reward is by no means the same thing as pleasure. In fact, some argue that the definition of reward is vague and inconsistent (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2759361/pdf/fnbeh-03-013.pdf).

    Dopamine is linked to the motivational aspects of ‘reward’ rather than the pleasure-inducing elements of positive reinforcement. For instance, manipulation of the dopamine system (pharmacological and/or genetic) is known to alter the degree of effort a subject is willing to exert in order to receive a reinforcer (food or drug reinforcers), however, 6-OHDA lesions leave the affective responses to sucrose in tact. Thus, it appears dopamine is not primarily involved in the pleasurable response to reward.

    There is no requirement to link dopamine to the hedonic components of reinforcer receipt in order to identify a role for dopamine in the motivational responses to both drugs of abuse or food. In this sense, it’s far less controversial to identify similarities between obesity and addiction whilst being able to avoid shoehorning the obese into the shoes of the addict.

    As a footnote, I’m not convinced proponents of the dopamine theory of addiction principally view addiction as ‘essentially about reward (pleasure)’. In fact, there are theories arising from dopamine studies (cf Robinson and Berridge, 1993) which argue that addiction is a problem of wanting (motivation) rather than pleasure ((hedonics) see above). These theories are by no means free from controversy. However, they provide a wonderful demonstration of the incredible complexity of the dopamine debate.

  • Tommy T

    In my intro to psychology class we recently have been learning about neuroscience. I would agree that dopamine could be a cause in addiction to food to people because it releases a “pleasurable and rewarding sensation” which people get when they eat because they are hungry. Depending on what the person is eating when they get those feelings may cause an addiction especially with fast food.

  • http://twitter.com/EdwardLPlatt Edward L Platt

    You raise an interesting question. If “everything from food to friends” triggers the release of dopamine, how are addictive stimuli different from other rewarding stimuli.

    I have to second the above poster and point out that I’ve never heard anyone who actually studies the connection between dopamine and addiction suggest that dopamine represents pleasure. The two common claims I’ve heard are that dopamine (in the reward pathway) represents incentive salience, or that it represents the error between predicted and received reward.

    When discussing dopamine and addiction, you have to consider time. Yes, all those things trigger dopamine release, but how does that response change after repeated exposures?

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      It’s true few people would explicitly argue that ‘dopamine = pleasure’ straightforwardly. But I get the impression that this is an idea that lurks in the background of much of dopamine neuroscience, you can see it in e.g. the quote:

      “the ingestion of palatable food releases dopamine in the striatum, in
      proportion to the ratings of meal pleasantness, and activates reward
      circuitry…”

      • http://twitter.com/Dave__M Dave

        Most people do explcitly argue that dopamine is not pleasure in affective neuroscience, though. Few would argue against the idea that, in the normative state, most people want what they like.

        Evoked dopamine release in the nucleus accumbens shell habituates in response to palatable foods in non-food deprived rats.

  • Aiyana

    It is said what causes addiction is caused by whatever the addictive substance may be and that substance prevents normal neurotransmitter activity, because of that new behavior is formed. One neurotransmitter that plays a major role in addiction is Dopamine. Dopamine is a chemical messenger which is similar to adrenaline aka Serotonin. Dopamine affects brain processes that control movement, emotional response, and ability to experience pleasure and pain. So when we do that potentially addictive activity i.e. eating our favorite foods we get a pleasurable experience of it and the dopamine that is produced makes you crave it more. The same goes for using narcotics and other illegal drugs. Those drugs bind to dopamine receptors in place of dopamine and directly stimulate those receptors, acting as a dopamine antagonist. When dopamine or dopamine antagonist frequently stimulate the dopamine receptors your dopamine levels actually decrease and make it harder and harder to experience that pleasure you once had. This is why it is said drug addicts are always trying to “chase their first high”.

  • Rolf Degen

    I once read that there is a big difference in the quantity of dopamine released by drugs and by natural behaviors. The quotation is this:

    “For one thing, says longtime addiction researcher Roy Wise of NIDA, drugs are far more powerful than any “natural” pleasure when it comes to the amounts of dopamine released.”

    “Behavioral Addictions: Do They Exist?” (SCIENCE VOL 294 2 NOVEMBER 2001)

    So if this diffference is true, it could be a principal one that separates the two domains.

  • http://twitter.com/jjodx JJ

    That makes me think of the work of Serge Ahmed who showed that rats prefer sweet food over cocaine… He also suggested that such addiction to sweet food might explain the number of obese people…

  • http://twitter.com/infinidiv infinidiv

    As interesting as this finding may prove to be in treating eating
    disorders or helping people without a disorder not to overindulge on a
    daily basis… I don’t really find the concept itself particularly new
    and exemplifies one of my issues with neuroscience in general. Don’t get
    me wrong, I am a neuroscientist myself (my defense is in may), but many
    of the findings in neuroscience are actually more of a new view on
    something already known. That does not make it useless by far. It will
    help us in the long run to deal with such issues better. But considering
    the long-known association of depression and eating disorders for
    example, it is clear that the association of “making yourself feel
    better” from food is something we have been dealing with for a while…
    there are just more of those people around today apparently, or maybe
    just more food. So while the finding is interesting, I don’t think it is
    ground-breaking, or that with will drastically change how we try to
    help people with such a problem.

  • http://jayarava.blogspot.com Jayarava

    I don’t imagine eating to satisfy hunger is addictive at all. One feels hungry and eats until satiation ensues and then stops. There is a feedback mechanism and when it works well people are not obese.

    However when we eat for reasons other than hunger – which so many of us do now, then the feedback mechanism gets broken. If we eat (only) for pleasure, for comfort, to dampen anxiety, out of boredom, then I imagine this pleasure/dopamine thing works just like addiction. David J Linden makes this case in his book “Pleasure”.

    From my perspective it’s not the pleasure that is bad, but the pursuit of pleasure in place of anything more meaningful – the Benthemite idea that pleasure = happiness. I think this is neopuritanism – it’s more thought out and not against pleasure per se, but against the pursuit of pleasure as a means to happiness.

  • http://www.facebook.com/nick.stuart.545 Nick Stuart
  • petrossa

    I guess the ‘we are not animals’ meme still reigns strong. Good survival tactic for any animal to eat a much as it can when there is plenty since you never know when your next meal will be. That that therefor is an integral part of our hardwire since forever is blatantly so obvious it’s insulting to the intelligence to read such pseudo-scientific nonsense as this paper.

  • hnarf

    Even if staying strictly within the confines of a dopamine payoff model of addiction, it seems to me that beyond the mere ability to produce pleasure, the question of tolerance also needs to be taken into account when considering whether some particular activity deserves to be considered potentially addictive – whether, or to what extent, repeated indulgence reduces the “hedonic payoff” of a given degree of stimulus, thus requiring stronger stimulus to reach the same level of pleasure, as seems to be the case with both food and addictive drugs, but probably much less so with other dopamine inducing things like, to take examples from the chart, friends, music or nature. Beyond that there is of course also the question whether increased stimulus will continue to produce increased payoff at all, or whether, or how quickly, one reaches a peak after which continued activity becomes increasingly unpleasant.
    Activities for which tolerance develops quickly, but where pleasure increases with increased stimulus to a great degree will almost certainly be more addictive than activities which satisfy these conditions less, even if their dopamine payoff is the same or even slightly higher.

  • Stephan Guyenet

    I respectfully disagree with Dr. Volkow that obesity is a form of addiction (or at least resembles it closely on a neurobiological level). That being said, most would categorize binge eating as a form of food addiction, and binge eaters do have a high prevalence of obesity (though most obese are not binge eaters).

    Reward is not inherently harmful, in fact it is good by and large– that’s why the mechanism evolved. Reward (motivation, pleasure, reinforcement) is designed to cause us to seek out natural stimuli that increase the probability of survival and reproduction. That’s why food and sex are so rewarding.

    The problem occurs when the rewarding stimulus is too strong– when it goes beyond an organism’s hard-wired tolerances. Processed food, pornography, and drugs of abuse are all “superstimuli” that hit reward pathways with enough force to exceed natural tolerances and cause pathology in susceptible people. Even among people who do not become addicted to these “unnatural” rewards, they can still drive behavior. For example, many people drink alcohol responsibly, while a minority become addicted. Beer, wine and spirits wouldn’t even exist if ethanol didn’t act on reward pathways. Ethanol would be a lab solvent and nothing more. The same is true of hyperpalatable processed foods– they can drive eating behavior whether or not they cause addiction.

  • Pingback: That Was the Week That Was (#311) | The Honest Courtesan()

  • Body Wisdom Videos

    What a misleading article. You state that “addiction is about reward”. Addiction is not about reward, it is a decline in reward, along with extreme sensitization to the substance or activity. In other words addiction is what occurs to brain when chronically high levels of dopamine in the nucleus accumbens cause an accumulation of deltafosb leading the addiction phenotype of craving and continued use despite negative consequences. This involves multiple complex changes. See Nestler.

    Either you don’t understand the basics of addiction neuroscience or your intent is to confuse the lay public.

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      I don’t think you’ve understood the point of this post. What I’m asking is, what makes something addictive? Is something addictive because it is highly rewarding (in which case addiction is “about” reward)? That seems to be the message of some of the addiction literature. Or alternatively, could something be highly rewarding and not addictive, & vice versa?

  • Pingback: Food Addicts Anonymous? | Neurobites()

  • Pingback: URL()

  • Pingback: The Neurobiology Of Abuse, Addiction And Chemical Dependency - AWAREmed Addiction Training()

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Neuroskeptic

No brain. No gain.

About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

ADVERTISEMENT

See More

@Neuro_Skeptic on Twitter

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »