Alcohol and Adolescent Brain Development
Adolescence is a time of transition, physically, socially, and emotionally. The adolescent brain is in transition as well. Although important structural and functional changes take place in the brain from childhood to adulthood (Giedd et al., 1999), during adolescence such changes are widespread. During adolescence, the brain undergoes a major remodeling involving the formation of new connections between nerve cells, as well as the pruning of existing synaptic connections. These changes affect the processes involved in planning and decisionmaking, impulse control, voluntary movement, memory, and speech production, among others (Rubia et al., 2000). Similar changes occur in those parts of the brain that seem to affect how a person responds to alcohol and other drugs (Spear, 2000; Teicher et al., 1995). As a result, alcohol appears to have different effects on adolescents than adults (Spear, 2000).
Animal studies suggest that alcohol may have a greater impact on adolescent than adult memory (Markweise et al., 1998; Pyapali et al., 1999) and that these effects may be long lasting. Preliminary studies suggest that rats exposed to high levels of alcohol during adolescence may be more sensitive to alcohol-induced memory impairments later in life (White et al., 2000). Human studies have detected cognitive impairments in adolescent alcohol abusers weeks after they stopped drinking (Brown et al., 2000).
Although the causes of these long-lasting changes are unclear, they may in some cases involve alcohol-induced injury to the nervous system. In rats, exposure to high amounts of alcohol produces more extensive brain damage in adolescents than adults (Crews et al., 2000). In humans, adolescent-onset alcohol abuse has been associated with a reduction in the size of the hippocampus (DeBellis et al., 2000).
Research also suggests that adolescents are less sensitive than adults to some of alcohol's effects. For example, adolescent rats, on their first exposure to alcohol, are less susceptible than adult rats to alcohol's sedative effects, as well as its effects on balance and motor coordination (Little et al., 1996; White et al., 2001). It is not known whether these differences occur in humans. However, the findings suggest that adolescents might be able to stay awake and mobile at higher blood alcohol levels than adults with an equivalent history of alcohol exposure while, at the same time, experiencing greater alcohol-induced cognitive impairments and, possibly, more injury to the brain following high alcohol exposure levels.
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Last reviewed: 9/23/2005