Summary
       While the overall size of the brain increases little beyond early childhood, important structural and functional changes take place as one progresses from childhood to adulthood (Giedd et al., 1999). Recent evidence suggests that, as a result of the changes in brain function that occur during adolescence, alcohol affects adolescents differently than it affects adults (for review see Spear, 2000). Adolescent rats are more vulnerable than adults to the effects of alcohol on memory (Markweise et al., 1998), a finding that might stem from developmental changes in the impact of alcohol on the functioning of a part of the brain known as the hippocampus (Pyapali et al., 1999).
       It also appears that adolescents might be particularly vulnerable to the long-lasting effects of alcohol use. Preliminary data suggest that alcohol exposure during adolescence makes rats more sensitive to alcohol-induced memory impairments later in life (White et al., 2000). In humans, cognitive impairments have been detected in adolescent alcohol abusers weeks after they stop drinking. The causes of these long-lasting changes are unclear, but they might involve brain damage and/or alterations in normal brain development. In rats, alcohol exposure produces more extensive brain damage in adolescents than adults (Crews et al., 2000). In humans, alcohol abuse during adolescence has been associated with a decrease in the size of the hippocampus (DeBellis et al., 2000).
       The available evidence suggests that adolescents might actually be less sensitive than adults to some of the effects of alcohol. Adolescent rats are less vulnerable than adults to the sedative effects of alcohol, as well as to the effects of alcohol on balance and motor coordination (Little et al., 1996; White et al., 2001). While it is not known whether these differences occur in humans, the findings suggest that adolescents might be able to stay awake and mobile at higher blood alcohol levels than their adult counterparts, all the while being more vulnerable to alcohol-induced cognitive impairments and, perhaps, brain damage.