Researchers said alcohol-use disorders are known to be associated with abnormalities of the prefrontal cortex, thalamus and the cerebellar hemispheres in adults' brains.
The new study of those same brain structures in adolescents and young adults with alcohol-use disorders has found a smaller prefrontal cortex.
But scientists said they are still uncertain whether that represents a vulnerability to, or a consequence of, early onset drinking.
"This is the first study to examine the sizes of these brain structures in adolescents and young adults," said Michael De Bellis, professor of psychiatry and behavioral sciences and director of the Healthy Childhood Brain Development Research Program at Duke University Medical Center.
He said adolescents were defined as 13 to 17 years of age, and young adults were defined as 18 to 21 years of age. All of the study's subjects were recruited from substance-abuse treatment programs, and had co-existing mental-health disorders.
The research is detailed in the September issue of Alcoholism: Clinical & Experimental Research.