Rada, N.M. Aveda, and B.G. Hoebel. Daily Bingeing on Sugar Repeatedly Releases Dopamine In The Accumbens Shell, Neuroscience.
We’ve all had those moments when we go on a health kick and change our diet. We eat healthy foods during the day, but sometimes we get those insatiable sugar cravings at night. You think to yourself that you deserve a sugary treat for cutting back! One candy bar can’t hurt, right?
What if I told you that midnight snack could actually make your sugar cravings worse? Researchers at Princeton University have found that repeated binges of sugar cause chemical patterns in the brain 
similar to drugs. Here’s the theory: addictive drugs, the ones that give us highs and that addicts take compulsively, all have a common chemical effect. They increase the neurotransmitter dopamine in a specific part of our brain linked to addiction [1]. Dopamine also gets released in this part of the brain when we eat delicious food, like candy. However, unlike drugs, dopamine decreases during the course of a long meal and with repeated consumption [2]. We also have a chemical called acetylcholine that gets released towards the end of the meal and makes us feel full. We don’t have this control mechanism with drugs, and many addicts find themselves increasing drug intake with each use [3].
Normally our balance of these two neurotransmitters keeps us from overeating. However, previous research shows that under certain conditions rats can develop addictive behaviors towards sugary food [4]. These studies inspired researchers to investigate if sugar bingeing could cause addiction-like dopamine release in rats. One group of rats was allowed to ‘binge’ on sugar for an hour each day, a different group had access all day, while a third group was only allowed sugar twice.
The researchers found that unlike normal conditions, the binging rats had increased dopamine release every single day. Acetylcholine release
was also delayed in these rats, which means that their ‘stop eating’ signal was much slower. This pattern of increased dopamine and delayed acetylcholine mirrors the chemical pattern of drug addiction. Also like the dose escalation of drug users, these rats ate more sugar over time, even more than the rats who had access all day!
So what does this mean for us human sugar-eaters? “We aren’t necessarily saying that sugar is as dangerous as drugs like cocaine, but we should be thinking critically about how we eat,” suggests Rada, “consistent, bursts of sugar could be more harmful than we first thought”* [4]. So much of the diet industry focuses on what we consume instead of how and when. By understanding unhealthy eating habits on a neuronal level, we can figure out the best ways to eat healthy and avoid these addictive behaviors.
As a nation, we need to reassess our eating habits to combat the obesity epidemic. In this study the researchers don’t actually note if the bingeing rats were overweight. So we don’t know if this eating pattern leads to obesity, just that it has addictive qualities. But by knowing more about how eating affects our brain we can look to a healthier future.
Acknowledgements: Ray Miao (Motivation and Reward student), Ariel Ben-Ezra (friend and Motivation and Reward student), Molly Cohn (friend and government major), Laurie Sproul-Poisson (mother), and Professor Robinson all provided valuable feedback on this article.
Bibliography
Images:
- Keifer C. Photographer. A Fat Rat Named Drusilla Eating Candy and Cookies [Digital Image], Retrieved From http://nansenneuro.net/images/rat-candy.jpg
- Woman Snorting Donuts [Digital Image], Retrieved From http://mamasanity.com/wp-content/uploads/2014/10/woman-snorting-doughnuts.jpg
References:
- Rada P, Mark GP, Pothos E, Hoebel BG. (1991). Systemic morphine simultaneously decreases extracellular acetylcholine and increases dopamine in the nucleus accumbens of freely moving rats. Neuropharmacology, 30, 1133–1136.
- Di Chiara G, Tanda G. (1997). Blunting of reactivity of dopamine transmission to palatable food: a biochemical marker of anhedonia in the CMS model? Psychopharmacology, 134, 351–353; discussion 371–377.
- Mark GP, Rada P, Pothos E, Hoebel BG. (1992). Effects of feeding and drinking on acetylcholine release in the nucleus accumbens, striatum, and hippocampus of freely behaving rats. J Neurochem, 58, 2269 –2274.
- This is a quote paraphrasing the authors’ findings. They didn’t really say this, but it’s what their work is pointing towards.