Previous research has shown that alcohol-use disorders (AUDs) are associated with abnormalities of the prefrontal cortex, thalamus and the cerebellar hemispheres in adults.
These same brain structures are known to be actively maturing during adolescence. An examination of adolescents and young adults with AUDs has found that a smaller prefrontal cortex is associated with early-onset drinking. Results are published in the September issue of Alcoholism: Clinical & Experimental Research.
"This is the first study to examine the sizes of these brain structures in adolescents and young adults," said Michael D. De Bellis, professor of psychiatry and behavioral sciences and director of the Healthy Childhood Brain Development Research Program at Duke University Medical Center, as well as corresponding author for the study.
"Studies on adults with alcoholism have generally shown smaller brain sizes, but this is after many years of very heavy drinking," added Susan Tapert, associate professor of psychiatry at the University of California at San Diego. "Before this study, it really wasn't clear that adolescents, with briefer drinking histories, would show any differences in brain size. However, with nearly one in three high-school seniors binge drinking at least once per month, it is critical that we understand precisely how drinking affects the brain of these young people."
Researchers used magnetic resonance imaging to measure prefrontal cortex, thalamic, and cerebellar volumes in 14 subjects (8 males, 6 females) with AUDs, and in 28 (16 males, 12 females) sociodemographically similar individuals without AUDs, known as "controls." 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 subjects with AUDs were recruited from substance-abuse treatment programs, and had co-existing mental-health disorders. Controls were recruited from the community via advertisement.
"Our findings show that adolescents and young adults with AUDs had a smaller prefrontal cortex and prefrontal cortex white-matter volumes compared with controls," said De Bellis. "Right, left and total thalamic, pons/brainstem, right and left cerebellar hemispheric, total cerebellar, and cerebellar vermis volumes did not differ between groups. There was a significant sex-by-group effect, in that males with an adolescent-onset AUD compared to control males had smaller cerebellar volumes, whereas the two female groups did not differ in cerebellar volumes. Also, prefrontal cortex volume variables significantly correlated with measures of alcohol consumption. Taken together, these findings suggest that a smaller prefrontal cortex is associated with early-onset drinking in individuals with co-morbid mental disorders, which are very common in adolescents with drinking and drug problems."