Alcohol on the Mind: The Effects
of Drinking on the Adolescent Brain
By Jerry Gabriel
September 2000

Scientists have noted over the years a litany of consequences associated with underage drinking. According to Dr. Enoch Gordis, director of the National Institute of Alcohol Abuse and Alcoholism, the list includes: "interference with learning, social, and other competencies, fatal traffic crashes, [alcohol-related] injuries, homicide, suicide, and early, more frequent, and less safe sexual activity."

We can now add to this list that evidence has shown that alcohol is actually damaging the brains of adolescents who drink heavily. Two recent studies, each published in the journal Alcoholism: Clinical & Experimental Research, have examined the effects of alcoholism and binge drinking on the minds of adolescents; the results do not bode well for the underage keg culture.

A recent study showed that teens who drink heavily and over a long period of time showed "deficits in retrieval of verbal and nonverbal information and [visual spatial] functioning," performing poorly on "tests of learning and memory,... planning, and cognitive flexibility." This study of 33 15- and 16-year-olds with protracted alcohol use--a measure the researchers defined as over 100 lifetime alcohol episodes--was conducted by Dr. Sandra Brown and her colleagues at the University of California at San Diego's Department of Psychology.

Follow-up fMRI studies, says project scientist and research fellow Dr. Susan Tapert, have confirmed the earlier findings: "With regard to the posterior parietal regions (upper back of the brain), we found a large area back there that did not appear to become active during a task that requires intensive activation in this area."

Why would heavy drinking be more dangerous at 15 years than just a handful of years later, at 20?

This, says Tapert, is the question their team is interested in understanding. It is their belief that the processes of myelination and synaptic pruning that continue through late adolescence might hold the answer to the question. Both of these processes work to refine connections in the brain "that make thinking more efficient."

"We think, but don't know for sure," Tapert says, "that it may be more dangerous for a 15-year-old to drink heavily than for a 20-year-old because these finishing touches on brain development haven't completed and could be interrupted or disturbed."

Dr. Aaron White and his colleagues at Duke University's Department of Psychiatry have recently added to this conversation through a study of binge-drinking in adolescent rats. The researchers were essentially testing whether binge-drinking "enhances responsiveness to the memory-impairing effects of ethanol in adulthood." That is to say, if some alcohol has deleterious effects on memory, can we expect a lot of alcohol to exacerbate the situation?

In the study, rats were injected with ethanol either as adolescents or adults, and then, 20 days after the final injection-when all animals were adults-the animals were trained in a spatial working memory task involving food rewards. Though there were no appreciable differences in the memory of the two groups of rats on five minute and one hour delays. But the rats treated with ethanol as adolescents proved to exhibit "larger working memory impairments during an ethanol challenge"-a later injection of alcohol-"than subjects in the other...groups."

The implications of this seem to be that binge-pattern exposure to alcohol during adolescence makes the brain more sensitive to alcohol in the future. Though White admits that it's tricky business drawing conclusions about human adolescents from rodents, he does say that "the findings from our studies with rodents fit very nicely with findings from Dr. Brown's research and the research of others. There is a story emerging from both the human and non-human literatures, and the story is that alcohol abuse during adolescence can have long-lasting consequences on brain function and cognitive abilities."