Compulsive Eating is Similar to Alcohol and Drug Addictions

Compulsive eating has been described as a type of addiction since excessive overeating can affect the same reward system in the brain that is altered by substance abuse. Although compulsive eating is not currently classified as a distinct psychiatric disorder, recent research has not only revealed that compulsive eating shares similar characteristics with alcohol and drug addictions, but clinical treatment methods for compulsive drug disorders may also help treat compulsive eating behavior.

A new study by researchers from the Ernest Gallo Clinic and Research Center, an affiliate of the University of California, San Francisco, has discovered that ezlopitant, a drug compound known to suppress alcohol cravings, has the potential to suppress sugar intake as well.

Ezlopitant is a type of neurokinin 1 (NK1) receptor-antagonist—a class of medications that have novel antidepressant, anxiolytic, and antiemetic properties. NK1 receptor-antagonists have the ability to suppress the neurotransmitter known as substance P, which is involved in the brain’s reward circuitry. The reward circuitry, when conditioned to substance abuse, manages dopamine levels in the brain that process drug cravings and rewards through its neurotransmission. In this reward circuitry, substance P is released in response to a stimulus; in order to generate an effect, this neurotransmitter must bind with a NK1 receptor. By introducing ezlopitant to this environment, substance P is prevented from binding to the NK1 receptor, and the craving is suppressed.

While ezlopitant has been effective in suppressing the neurotransmission that governs alcohol cravings, researchers Selena Bartlett and colleagues have now found that the same brain pathways may share a link with compulsive eating.

The researchers attribute foods that are high in sugar to be the driving force behind overeating compulsions. In their study, Bartlett and her team sought to identify if the NK1-receptor systems involved in drug cravings also plays a role in sugar cravings. The researchers used three groups of rats that had access to different water solutions. The water sources contained plain water, sugar water, water with saccharin, water with salt, or water mixed with ethanol. After allowing the rats to self-administer the various water solutions, the rats were administered the NK1-receptor antagonist ezlopitant. As a result, the rats showed significantly less motivation to seek and consume the water containing sugar, saccharin, or ethanol. In fact, ezlopitant decreased the rats’ appetite for the sugar- and saccharin-sweetened water even more than the ethanol solution. Furthermore, the ezlopitant did not interfere with the rats’ normal locomotor activity, or their tendency to consume the plain water or salty solution.

The study’s findings are the first to identify the NK1-receptor as playing a significant role in compulsive eating. The researchers purport that the NK1-receptor system involved in sugar cravings is also related to the same reward circuitry for drug cravings. Although their latest experiment with ezlopitant involved an animal sample, the researchers hope to further investigate the NK1-receptor antagonist in human trials.

The researchers’ study was published on September 1 in the online scientific journal PLoS ONE.

Source: Medical News Today, Addiction, Compulsive Eating May Be Linked By Biochemical Pathway, September 2, 2010

Tags: compulsive eating, Food Addiction, treatment