People Who Lack Interest in Food May Be More Prone to Drug Addiction
Food addicts are less likely to be interested in cocaine and vice versa, according to a study by Yale School of Medicine researchers who found that the same neurons that control overeating also drive the appetite for the illicit drug.
Because of the way the brain's reward circuits are set up, it's been previously suggested that the root of obesity may stem from a kind of overlap in the brain - food can become a type of 'drug of abuse' similar to cocaine. Overeating that may help to contribute obesity is often lumped together with an increased pleasure-seeking drive, reports Medical Daily. But this study flips that common wisdom on its head, finding just the reverse.
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"Using genetic approaches, we found that increased appetite for food can actually be associated with decreased interest in novelty as well as in cocaine, and on the other hand, less interest in food can predict increased interest in cocaine," said study lead Marcelo O. Dietrich.
The reward centers located in the midbrain are the key to this work. Dietrich and his colleague Tamas L. Horvath studied two sets of transgenic, or genetically altered, mice. In one set, they knocked out a signaling molecule that controls hunger-promoting neurons in the hypothalamus. In the other set, they interfered with the same neurons by eliminating them selectively during development using diphtheria toxin.
The mice were then tested to measure how they responded to novelty and anxiety, and how they reacted to cocaine.
"We found that animals that have less interest in food are more interested in novelty-seeking behaviors like drugs and cocaine," Horvath said. These findings only applying to mice, but with more research, this type of connection could apply to humans as well.
Scott Sternson, who studies the neurological processes behind hunger at Howard Hughes Medical Institute, told ABC News that the findings are unexpected and mean that scientists need to think more carefully about the wiring of the brain's reward system when it comes to food.
"It will really cause people to look at a new connection between how your body senses your energy levels and how that might affect your response to a drug of abuse like cocaine," he said.
Horvath and his team argue that the hypothalamus, which controls vital functions such as body temperature, hunger, thirst fatigue and sleep, is key to the development of higher brain functions. The impaired function of these hunger-promoting neurons could alter the higher brain functions, resulting in changes in motivated and cognitive behaviors, Horvath said.
"There is this contemporary view that obesity is associated with the increased drive of the reward circuitry," Horvath added.
"But here, we provide a contrasting view: that the reward aspect can be very high, but subjects can still be very lean. At the same time, it indicates that a set of people who have no interest in food, might be more prone to drug addiction."
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