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A habit of binge eating may make an individual more likely to show other addiction-like behaviors, including substance abuse, according to a new study. 

A study conducted by Penn State College of Medicine researchers revealed a link between bingeing on fat and the development of cocaine-seeking and -taking behaviors in rats, indicating that conditions promoting excessive behavior toward one substance can increase the probability of excessive behavior toward another. 

"While the underlying mechanisms are not known, one point is clear from behavioral data: A history of bingeing on fat changed the brain, physiology, or both in a manner that made these rats more likely to seek and take a drug when tested more than a month later," Patricia Sue Grigson, professor at Penn State said. 

The authors used rats to test whether a history of binge eating on fat would augment addiction-like behavior toward cocaine by giving four groups of rats four different diets: normal rat chow; continuous ad lib access to an optional source of dietary fat; one hour of access to optional dietary fat daily; and one hour of access to dietary fat on Mondays, Wednesdays, and Fridays. All four groups also had unrestricted access to nutritionally complete chow and water. The researchers then assessed the cocaine-seeking and -taking behaviors.

Fat bingeing behaviors developed in the rats with access to dietary fat on Mondays, Wednesdays, and Fridays -- the group with the most restricted access to the optional fat.

This group tended to take more cocaine late in training, continued to try to get cocaine when signaled it was not available, and worked harder for cocaine as work requirements increased.

While the consumption of fat in and of itself did not increase the likelihood of subsequent addiction-like behavior for cocaine, the irregular binge-type manner in which the fat was eaten proved critical. Rats that had continuous access to fat consumed more fat than any other group, but were three times less likely to exhibit addiction-like behavior for cocaine than the group with access only on Mondays, Wednesdays and Fridays.

"Indeed, while about 20 percent of those rats and humans exposed to cocaine will develop addiction-like behavior for the drug under normal circumstances, in our study, the probability of addiction to cocaine increased to approximately 50 (percent) for subjects with a history of having binged on fat," Grigson said.

The findings of the study appear in Behavioral Neuroscience.