Think of the human brain during adolescence as a city still under construction. Roads are being paved, bridges are going up, and entire neighborhoods are being wired for electricity. It is the most dynamic period of development the brain will ever experience. Now imagine that during the busiest phase of that construction, something starts interfering with the blueprints. That, in essence, is what Dr. Gerald Deehan, an associate professor in the experimental concentration in the Department of Psychology at East Tennessee State University, has devoted his career to understanding.
Dr. Deehan studies how alcohol exposure and stress during adolescence can alter the developing brain in ways that carry into adulthood, and potentially lay the groundwork for alcohol use disorder later in life.
“Your brain’s going to react in a certain way with alcohol or experience, and that can produce alterations in how the brain functions,” Dr. Deehan said. “If this is happening during a dynamic period of development, some of the circuits that are developing are being exposed to such things, and then those changes get cemented in place as development ends.”
Picture wet concrete. Pour it, shape it, and it will hold whatever impression is made before it sets. The adolescent brain works in a similar way. It is not finished hardening yet, which makes it especially vulnerable to experiences that should not be there.
Dr. Deehan points to a pattern that stands out in the research: the vast majority of adults who meet the criteria for alcohol use disorder report that they first started drinking during adolescence. That is not a coincidence. Most people’s first encounter with alcohol is not something harsh but something sweet, something carefully masked behind flavor. That reward is what starts the engine.
“You know, you might try something like a screwdriver, a drink that’s something to mask the alcohol,” Dr. Deehan said. “That reward side of things kind of is initiating the use.”
Over time, for some people, the motivation shifts. Instead of chasing a good feeling, the brain begins craving alcohol just to feel normal, dysphoric and withdrawn without it. Researchers call this negative reinforcement, and it is one of the hallmarks of addiction.
Dr. Deehan’s current research adds another layer: stress. Most people carry some level of stress most of the time, and adolescence is no exception. Stress can precede drinking, follow it, or run alongside it, and the relationship is less a straight line than a feedback loop. Each can amplify the other, and for a brain still under construction, that cycle may leave a lasting mark.
“We’re trying to figure out whether the stressful aspect leads to higher levels of consumption later in life,” Dr. Deehan said. “Your brain is developing in adolescence, and we want to look at factors that may affect that development in such a way that it predisposes the person to higher levels of alcohol use later on.”
Another dimension of Dr. Deehan’s research centers on cues, the people, places, smells, and situations the brain learns to associate with drinking. Think of walking into a place where you have always had a drink, or catching a familiar scent that the brain has quietly filed away next to the memory of alcohol. That association can trigger cravings all on its own. Dr. Deehan’s lab studies how these cue associations form during adolescence and how powerfully they drive alcohol-seeking behavior later in life, even long after the original exposure.
“You see a pretty significant effect just in response to the flavor, just the smell,” Dr. Deehan said. “You walk into a house and you smell your mom’s cooking, and now you’re getting hungry. It works the same way.”
“There’s so many different things that can contribute,” Dr. Deehan said. “Some people can drink alcohol socially and maintain a level that does not impede their life, while others don’t.”
As addiction continues to affect communities across the country, Dr. Deehan and his lab at ETSU are working to unravel the complex web of factors that shape a person’s relationship with alcohol long before adulthood.
