Saturday, April 9, 2011

A Small Post On The Neurobiology of Binge Eating Disorders

Indulge me for a moment. Here is one of my favorite pieces of music: Chopin's Etude No. 3 in E major. (right click to open in new window). The best youtube quote about it: "Too beautiful to be an etude."

One more indulgence. A quote from A Room with a View by E.M. Forster. For springtime.

From her feet the ground sloped sharply into view, and violets ran down in rivulets and streams and cataracts, irrigating the hillside with blue, eddying round the tree stems, collecting into pools in the hollows, covering the grass with spots of azure foam. But never again were they in such profusion; this terrace was the well-head, the primal source whence beauty gushed out to water the earth.
Standing at its brink, like a swimmer who prepares, was the good man. But he was not the good man that she had expected, and he was alone.

The brain is named in beautiful words, intimidating words, but beautiful nonetheless. We'll start with the animal models of binge eating (1), which seem to have something in common with the human experience. Animals seem more likely to binge in cases of prior food restriction (and the bingeing can continue for long periods after restriction is over), and in periods of anxiety.

Daily binge eating on a "palatable sugar solution or fat diet" will repeatedly release the feel-good chemical dopamine from its home, the nucleus accumbens. Sugar-bingeing rats will have increased dopamine1 receptor binding in the nucleus accumbens, and decreased dopamine2 receptor binding in the dorsal striatum. This pattern is very similar to changes observed with drug dependency. There are also changes in opiate receptor expression in binge eating rats, and if you inject opiate into the nucleus accumbens, it will stimulate binge eating.

Some facts about binge eating in humans - the definition is that someone will eat an "objectively large amount of food" accompanied by feelings of loss of control. 30% of obese individuals attending weight control programs have the disorder. Obese binge eaters will eat significantly more calories than obese nonbinge eaters in order to feel full, or even when asked to eat normally.

In a study on humans, Wang et al discovered that food stimulus significantly increased dopamine signals in binge eaters in the basal areas of the brain, whereas non binge-eaters did not show the same increase.
Previous studies had shown that exposure to "palatable food stimuli" was associated with an increase in striatal dopamine release, and this release was correlated with ratings of "meal pleasantness" following consumption of favorite food. As with the other studies of folks with eating disorders, low dopamine levels (associated with an increase in receptors, to compensate) has been shown to be present in binge eaters.

People with binge eating disorder tend to overeat compulsively and have some impulsivity (also seen in substance abusers), and food is a potent reinforcer of the behavior, and fasting can enhance the rewarding effects (thus my little caveat about IFing and eating disorders).

Here's the evolutionary psychiatry money quote from the Wang article: "Some ingredients in palatable food such as sugar and corn oil can result in impulsive ingestion in patterns reminiscent of those seen with drug intake in addiction." DING DING DING DING.

And the sweet taste of sugar, without the nutritional component, can also induce release of dopamine (um… diet coke addiction, anyone?).

So I don't think I venture far out on a limb to suggest that eating disorders are addictive, or that certain types of extremely palatable food (sugar and corn oil, and in my clinical experience, for some people, wheat) are addictive. Abstinence with support is the tried and true method to help addictions. Hard, though, to get the appropriate sort of universal support when your government (and therefore any trained nutritionist or dietician or doctor of the conventional stamp) is telling you to eat corn oil and grains and carbs to lose weight and to be healthy in general.

Oh! Totally forgot to link yesterday in this blog - a new Psychology Today post is up. Click for me if you please!

6 comments:

  1. "And the sweet taste of sugar, without the nutritional component, can also induce release of dopamine (um… diet coke addiction, anyone?)"

    Thats a shocking realisation, I do indeed find myself somewhat addicted to diet soda.

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  2. It starts with just the perception of the stimuli and is in reinforced by the leptin receptors on the tongue. All artificial sweeteners do this along with sugar grains wheat and corn oil. Great reminder Dr Deans and we are clicking for you.
    Dr. K

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  3. Dr. Deans, thank you very much for the lovely Chopin Etude. Here is another gem of an etude, played by the amazing Arthur Rubinstein. A delightful film excerpt.

    http://www.youtube.com/watch?v=C90Mz4hvAzI&feature=channel_video_title

    Congratulations on another super article at Psychology Today. I hope you are reaching many.

    Your thoughts on our relationship to food and our own thinking and behavior about food and food habits are a delight to read and most useful in looking at my own habits in new ways.

    Thank you for you kind work in offering your blog and the articles. They are a blessing.

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  4. Emily I found something Germaine to your practice and mine as a neurosurgeon. Arch Gen Psychiatry, 2011; 68:128-137. Feb 2011. Not surprising to me at all considering how many scans I see that verify this

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  5. I'm on my phone waiting for my husband to come and change my tire (flat, nail, raining, I'm in heels for work, that's why you get married...) but is that the brain shrinkage study? Scary. There was a good analysis in psychiatric times this week. Do I have your email? Shoot me a comment with it and I won't publish and I can send you the text of the other article. If it is not the shrinkage study ignore this! But it must be...

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  6. Hello,

    This is the perfect blog for anyone who wants to know about this topic. Neurobiology looks at the brain and the nerve cells that connect to form the brain, which branch of biology that is concerned with the anatomy and physiology of the nervous system....

    Drug Discovery

    ReplyDelete