A new study into the hows and whys of alcoholism sheds a bit of light on why some drinkers become addicted and others don't; or anyway, why some mice become addicted and some don't.
Jeff Weiner, Ph.D., professor of physiology and pharmacology at Wake Forest Baptist, and his colleagues used an animal model to look at the early stages of addiction and focused on how each animal responded to alcohol.
“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,” said Weiner, director of the Translational Studies on Early-Life Stress and Vulnerability to Alcohol Addiction project at Wake Forest Baptist. “We don't have a good understanding of what causes this vulnerability, and that's a big question.”
Typically, when a drug like alcohol is given to a mouse every day, the way the animals respond increases — they become more stimulated and run around more, Weiner said.
“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.”
Usually when researchers are studying a drug, they give it to one test group while the other group gets a control solution, and then they look for behavioral differences between the two, Weiner said. In this study, researchers focused on individual differences in how each animal responded to the alcohol.
“We found large variations in the development of locomotor sensitization to alcohol in these mice, with some showing robust sensitization and others showing no more of a change in locomotor activity than control mice given daily saline injections,” Weiner said. “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.”