The neural circuit in our brains that causes us to compulsively overeat and become addicted to sugar has been identified. And researchers have found that they can target it in mice without interrupting normal feeding behaviour.
"Although obesity and Type 2 diabetes are major problems in our society, many treatments do not tackle the primary cause: unhealthy eating habits," one of the lead researchers of the study, Kay Tye from the Massachusetts Institute of Technology, said in a press release.
"Our findings are exciting because they raise the possibility that we could develop a treatment that selectively curbs compulsive overeating without altering healthy eating behaviour."
Compulsive overeating is a reward-seeking behaviour, which means that it’s similar to drug addiction. Because of this, Tye and her team suspected that the region of the brain that controls uncontrollable eating may be similar to the ones implicated in other addictive behaviours. Specifically, they suspected a bunch of cells linking the lateral hypothalamus - the region of the brain involved in hunger - to the ventral segmental area - where the brain's reward circuitry is located.
To test whether this was the case, the researchers used optogenetics, a technique where neurons are genetically modified so that they can either be activated or inhibited when scientists shine different coloured lights on them.
They found that, when the cell circuit in question was activated, mice spent more time sticking their noses into a feeding hole to receive a sugar treat, even when they were well-fed. They were so obsessed with getting more treats that even being given an electric shock to punish the behaviour didn't stop them wanting more.
But when the same pathway was inhibited in the brain, the mice stopped this compulsive sugar-seeking behaviour. And, importantly, this didn’t stop normal food consumption, which suggests that different neural circuits control healthy eating and addictive eating.
The team believes that the addictive neural circuit may have arisen in our evolutionary history make sure that our ancestors binged on anything they could get while food was scarce.
"However, in our modern day society, there is no scarcity of palatable foods, and high-sugar or high-fat foods are often even more available than fresh produce or proteins," said Tye in the release.
"We have not yet adapted to a world where there is an overabundance of sugar, so these circuits that drive us to stuff ourselves with sweets are now serving to create a new health problem. The discovery of a specific neural circuit underlying compulsive sugar consumption could pave the way for the development of targeted drug therapies to effectively treat this widespread problem."