Brain Structure in Adolescents and Young Adults with Alcohol Problems: Systematic Review of Imaging Studies

Aims: Alcohol-dependent people who are middle-aged or older have a widespread loss of cortical grey and white matter, particularly in the prefrontal cortex (PFC). We examine if brain abnormalities are detectable in alcohol use disorders before the fifth decade (i.e. < 40), and the brain structural differences associated with alcohol abuse/dependence in adolescence. Methods: Case-control studies comparing brain structure in alcohol-abusing/-dependent individuals with normal controls in which the mean age of participants was < 40 were identified using Medline, EMBASE and PsychInfo. Studies in which mean age was over and under 21 were considered separately. Results: Twelve papers fulfilled inclusion criteria, five in the adolescent (14-21) and seven in the young adult age range. Two independent groups reported hippocampal and prefrontal volume reductions in adolescents, although this was consistently observed only in females. In young adults (aged 21-40), there were grey matter deficits in the PFC in both sexes. Adult women appeared to, particularly, exhibit white matter differences, evident as reduced area of the corpus callosum. Hippocampal volume reduction was observed in one study of young adults study but not another. Conclusion: The available data suggest that quantitative structural abnormalities of the brain are detectable in young alcohol abusers. There is overlap between the abnormalities seen in adolescents and young adults, although hippocampal volume loss is most consistently seen in the former group. The adolescent hippocampus may be particularly susceptible to alcohol, potentially because of an interaction between adolescent brain development and alcohol exposure.