In adults, prefrontal, thalamic, and cerebellar brain injury is associated with excessive ethanol intake. As these brain structures are actively maturing during adolescence, we hypothesized that subjects with adolescent-onset alcohol use disorders, compared with control subjects, would have smaller brain volumes in these areas. Thus, we compared prefrontal-thalamic-cerebellar measures of adolescents and young adults with adolescent-onset alcohol use disorders (AUD, defined as DSM-IV alcohol dependence or abuse) with those of sociodemographically similar control subjects.
Magnetic resonance imaging was used to measure prefrontal cortex, thalamic, and cerebellar volumes in 14 subjects (eight males, six females) with an AUD (mean age, 17.0 ± 2.1 years) and 28 control subjects (16 males, 12 females; 16.9 ± 2.3 years). All AUD subjects were recruited from substance abuse treatment programs and had comorbid mental disorders.
Subjects with alcohol use disorders had smaller prefrontal cortex and prefrontal cortex white matter volumes compared with control subjects. 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, indicating that males with an adolescent-onset AUD compared with control males had smaller cerebellar volumes, whereas the two female groups did not differ in cerebellar volumes. Prefrontal cortex volume variables significantly correlated with measures of alcohol consumption.
These findings suggest that a smaller prefrontal cortex is associated with early-onset drinking in individuals with comorbid mental disorders. Further studies are warranted to examine if a smaller prefrontal cortex represents a vulnerability to, or a consequence of, early-onset drinking.