Cravings for chocolate reflect something more than a desire for comfort—namely an addiction triggered by a brain chemical, according to newly-published research.
The result is irresistibility to chocolate that is comparable to a drug addiction. Surges of a natural, opium-like chemical produced by the dorsal neostriatum—a brain region primarily linked to movement—contributes to generating intense consumption sweet treats and other “palatable” food, according to a study in rats by four University of Michigan, Ann Arbor investigators published in the journal Current Biology.
"The brain has more extensive systems to make individuals want to overconsume rewards than previously thought," Alexandra DiFeliceantonio, the study’s corresponding author and a doctoral candidate in the lab of another co-author, Kent Berridge, Ph.D., said in a statement. "It may be one reason why overconsumption is a problem today."
DiFeliceantonio's team found that rats ate more than twice the number of chocolate M&Ms they would otherwise eat after being injected with a synthetic form of the endorphin encephalin, a natural drug-like chemical produced in the neostriatum.
Researchers saw the same surge in M&M eating in another group of rats examined for how much enkephalin they produced naturally. Investigators concluded that enkephalin increased the rats’ desire and impulse to eat the M&Ms, but did not necessarily cause the animals to like the chocolate-coated candies more.
In humans, the neostriatum is active when obese people see foods and drug addicts see drug scenes. "It seems likely that our enkephalin findings in rats mean that this neurotransmitter may drive some forms of overconsumption and addiction in people,” DiFeliceantonio said.
Future research by the group of investigators will include the similarity of brain response using fast food rather than M&Ms as the stimulus.
[Read the study, "Enkephalin surges in dorsal neostriatum as a signal to eat," here: http://www.cell.com/current-biology/abstract/S0960-9822(12)00942-6]