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Dickinson and Fritz study effects of age, alcohol

By Catherine Monson '12
March 10, 2010

Researchers know that if people start drinking alcohol early in life, they’re more likely to develop problems with addiction later on. Yet scientists don’t have a clear understanding of the role tolerance plays during adolescence — a piece of the puzzle that St. Olaf Associate Professor of Psychology Shelly Dickinson is working to fill in with her current research.

In 2009 Dickinson received a $50,000 grant from ABMRF/The Foundation for Alcohol Research to support a one-year research sabbatical. The grant has funded the instrumentation and animals she needs in order to examine how adolescent and adult mice respond differently to alcohol exposure. She hopes to publish her findings later this year.

“It’s really helped me as a student and as a scientist to delve into this experience on my own and acquire these lab skills and these research skills,” says Brandon Fritz '10, pictured with Shelly Dickinson.

Brandon Fritz ’10, a psychology major who worked on several research projects with Dickinson last summer, is assisting with the tests and analyzing data as an independent research credit. “It’s really helped me as a student and as a scientist to delve into this experience on my own and acquire these lab skills and these research skills,” he says.

Using a simple model similar to Pavlov's dog demonstration, the experiments test whether mice show a preference for the place — in this case, a certain type of floor material — that they associate with the effects of alcohol. “We know that adolescent mice will develop a preference for cues paired with a certain dose of alcohol,” explains Dickinson. But the more interesting result she has found through her research is that younger mice require a higher dose of ethanol in order to show place preference. This "conditioning" process -- the association of environmental cues and drug effects -- is thought to be important in craving and relapse in humans, says Dickinson.

Another variation of the experiment tests how mice respond to an environment that they encounter just before the ethanol injection. In this case, the mice develop conditioned place aversion, which means they actively avoid the floor paired with alcohol. Dickinson explains that this aversion is an indicator of a sharp, but short-lived, negative feeling that mice get from being injected with ethanol. She calls it a “state change,” where the mice pass from a sober state to intoxication in a short period of time and which is associated with the somewhat novel environment just experienced. In humans, a similar feeling might occur when a large amount of alcohol is consumed over a short period of time.

The significant discovery is that adolescent mice can develop a tolerance to this negative effect more quickly than adult mice. But does the same thing apply to humans? The neurochemistry of the human and mouse brain is very similar and suggests that the same would be true for people, but both Fritz and Dickinson note that any correlation between humans and mice is hard to prove.

“If this whole thing about developing tolerance to this negative effect is true in humans,” says Dickinson, “it could increase consumption, since negative effects tend to act as a brake, slowing consumption. We don’t know if this negative effect is there, or how much control over behavior that might have, but it seems to fit with the high rates of binge drinking in the late teens and early 20s.”

So far, the results of the research will propagate more projects. Next, Dickinson would like to examine how the neurochemistry of the brain is involved in alcohol-related behavior. For Fritz, the research project has been a big step toward a prospective career in behavioral neuroscience and the psychobiology of addictions. But whatever direction their research leads to, Fritz, who will present the research at this year's Midbrains Conference at St. Olaf, feels it is an important contribution to our understanding of the effects of alcohol. “We know what we should be looking for and what we should be paying attention to,” he says, “so essentially that’s why we do these studies.”

Contact David Gonnerman at 507-786-3315 or gonnermd@stolaf.edu.