Behavioral tolerance is a common occurrence following exposure to drugs of abuse, characterized by reduced drug effect on a behavioral parameter, either via altered metabolism of the drug or via altered functionality, where the effects of the drug decrease in spite of unaltered concentration. Consequently, the user will escalate drug intake, to maintain the desired effect, with devastating results. There are multiple classes of tolerance, defined by the timeframe and pattern (e.g. constant versus intermittent) of exposure. Perhaps surprisingly for many readers, acute and rapid functional tolerance can occur within minutes of the first drink (this is addressed below) [1]. Importantly, the presence of enhanced acute behavioral tolerance to alcohol in humans can serve as a marker for the likelihood of the future development of alcoholism [2]. Thus, the teenager who can “drink his friends under the table” could be at greater risk for alcoholism than his buddies. Chronic tolerance is the decrease in sensitivity that develops as a result of repeated exposures to a drug and is measured in days or weeks rather than minutes [1]. Much remains to
