Adolescence. Alcohol sensitivity, tolerance, and intake.

Research conducted in laboratory animals has shown adolescents to be less sensitive to numerous ethanol effects that may serve as cues to limit intake, including effects evident during intoxication (e.g., ethanol-induced motor impairment, anxiolysis, social impairment, and sedation), as well as during the post-intoxication period (e.g., "hangover"-associated anxiogenesis). Conversely, adolescents are more sensitive than adults to a few ethanol effects, including ethanol-induced social facilitation and impairments in hippocampal long-term-potentiation. These age-specific ethanol sensitivities are not simply related to developmental differences in ethanol pharmacokinetics. Instead, they appear related in part to an ontogenetic decline in expression of within session (acute) tolerance and to differential rates of development of neural systems underlying different actions of ethanol. Relatively high levels of ethanol intake often seen in adolescent rodents and their human counterparts may be related not only to an attenuated sensitivity of adolescents to negative cues that normally serve to limit drinking, but also their greater sensitivity to both the facilitation of social behavior by ethanol and the stimulation of ethanol intake by social experiences. Although data are sparse, studies in laboratory animals hint that under some circumstances chronic adolescent exposure to ethanol may influence ongoing neural maturation and later neural, cognitive, and behavioral functioning, including later sensitivity to and propensity to use ethanol. Recommendations for further research are discussed.