Finding might yield new insights into eating disorders, experts say
WEDNESDAY, Dec. 10 (HealthDay News) -- Science is verifying what many overeaters have suspected for a long time: sugar can be addictive.
In fact, the sweetener seems to prompt the same chemical changes in the brain seen in people who abuse drugs such as cocaine and heroin.
The findings were to be presented Wednesday at the American College of Neuropsychopharmacology's annual meeting, in Nashville.
"Our evidence from an animal model suggests that bingeing on sugar can act in the brain in ways very similar to drugs of abuse," lead researcher Bart Hoebel, a professor of psychology at Princeton University, said during a Dec. 4 teleconference.
"Drinking large amounts of sugar water when hungry can cause behavioral changes and even neurochemical changes in the brain which resemble changes that are produced when animals or people take substances of abuse. These animals show signs of withdrawal and even long-lasting effects that might resemble craving," he said.
Dr. Louis Aronne, director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City, added: "The big question has been whether it's just a behavioral thing or is it a metabolic chemical thing, and evidence like this supports the idea that something chemical is going on."
A "sugar addiction" may even act as a "gateway" to later abuse of drugs such as alcohol, Hoebel said.
The stages of addiction, as defined by the American Psychiatric Association, include bingeing, withdrawal and craving.
For the new research, rats were denied food for 12 hours a day, then were given access to food and sugar (25 percent glucose and 10 percent sucrose, similar to a soft drink) for 12 hours a day, for three to four weeks.
The bingeing released a surge of the neurotransmitter dopamine each time in the part of the brain involved in reward, the nucleus accumbens. "It's been known that drugs of abuse release or increase the levels of dopamine in that part of the brain," Hoebel said.
But it wasn't only the sugar that caused this effect, Hoebel explained -- it was the sugar combined with the alternating schedule of deprivation and largesse. After three weeks, the rats showed signs of withdrawal similar to those seen when people stop smoking or drinking alcohol or using morphine.
The scientists next blocked the animals' brain endorphins and found withdrawal symptoms, anxiety, behavioral depression and a drop in dopamine levels. In other words, they confirmed a neurochemical link with the rats' behavior.
But longer periods of abstinence didn't "cure" the rats. Instead, there were long-lasting effects with the animals: They ingested more sugar than before, as if they were craving the substance and, without sugar, they drank more alcohol.
The researchers speculated that some of these brain changes may also occur in people with eating disorders such as bulimia and anorexia, although more research needs to be done to confirm the effects in humans.
"Some say it's easy to lose weight -- you just have to shut your mouth, stop eating so much," Aronne said. "I tell them a good way to overcome global warming is if people made less carbon dioxide by breathing less. Obviously, that's absurd. You can't do it because you feel uncomfortable.
"The same thing is true of eating," he added. "Fattening food has an impact on the regulating mechanism that breaks down your sense of fullness, makes you feel an urge to go back and get that blast of sugar and this creates the vicious cycle of weight gain that we're going through."
Visit Overeaters Anonymous for more on food addiction and eating disorders.
SOURCES: Louis Aronne, M.D., director, Comprehensive Weight Control Program, New York-Presbyterian Hospital/Weill Cornell Medical Center, New York City; Dec. 4, 2008, teleconference with Bart Hoebel, Ph.D., professor of psychology, Princeton University, Princeton, N.J.; Dec. 10, 2008, presentation, American College of Neuropsychopharmacology annual meeting, Nashville
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