A study of mice suggests why some people may be more susceptible than others to alcohol addiction. The findings may one day lead to improved treatments, according to the researchers from Wake Forest Baptist Medical Center in Winston-Salem, North Carolina.

The researchers studied how individual mice responded to alcohol. Lead author Jeff Weiner, Ph.D., explained when mice are given alcohol every day, they tend to become more stimulated and run around more, Science Daily reports.

“In high doses, alcohol is a depressant, but in low doses, it can have a mellowing effect that results in greater activity,” he said. “Those low dose effects tend to increase over time and this increase in activity in response to repeated alcohol exposure is called locomotor sensitization,” Dr. Weiner said in a news release.

One group of mice was injected with the same amount of alcohol every day for three weeks, while another group received a saline injection. They found a large variation in the development of locomotor sensitization to alcohol. “Surprisingly, when all of the alcohol-exposed mice were given an opportunity to voluntarily drink alcohol, those that had developed sensitization drank more than those that did not. In fact, the alcohol-treated mice that failed to develop sensitization drank no more alcohol than the saline-treated control group,” Weiner said.

“We know that some people are much more vulnerable to alcoholism than others, just like some people have a vulnerability to cancer or heart disease,” Weiner added. “We don’t have a good understanding of what causes this vulnerability, and that’s a big question. But if we can figure it out, we may be able to better identify people at risk, as well as gain important clues to help develop better drugs to treat the disease.”

The findings appear in the Journal of Neuroscience.