In the United States, adolescent alcohol abuse is widespread. Among adolescents, 20% engage in binge drinking, defined as more than 5 drinks in a row. That same study found that 16% engage in extreme binge drinking, defined as more than 10 drinks in a row. A study in 2006 found that adolescents who binge-drink are at a much higher risk of developing alcohol use disorder (AUD), a chronic relapsing brain disorder characterized by an impaired ability to stop or control alcohol use despite adverse social, occupational, or health consequences. While the sheer magnitude of alcohol abuse in young people is concerning, it’s crucial to determine what risk factors contribute to the development of AUD and what preventative measures (if any) can be taken.
When trying to find risk factors associated with disorders like AUD, it is important to consider both neurobiological state and environmental circumstances. Adolescents are at an age where they are constantly undergoing a wide range of hormonal, behavioral, and neuronal changes in their brain. This period of growth is a delicate time for the brain, and disruptions in neurological function can have wide-reaching and previously unforeseen effects. Scientists have been studying the effects of various drugs (i.e. marijuana, nicotine) on the adolescent brain, but an often-overlooked and unexpected drug affects millions of teenagers each year: anesthesia. A study looked at the effects of adolescent anesthesia-exposure on alcohol use.
One of the most common and safest anesthetics used in operation rooms is isoflurane. Isoflurane is given to patients via inhalation. In this study, rats were used to test the hypothesis that isoflurane exposure on adolescents would change how the rats responded to alcohol. While the rats were in adolescence, scientists administered one 40-minute dose of oxygen, as a control, or isoflurane. Afterward, the rats were given a series of tests related to alcohol use while they were still adolescents and again as adults.
Scientists found that adolescent anesthesia-exposure resulted in less aversion to bad tasting liquids, like salt water. Adolescent control rats disliked salt water as expected, but the anesthesia-exposed adolescent rats never exhibited aversion to any concentration of salt water given.
But how did the rats respond to alcohol? Isoflurane-exposed rats actually consumed more alcohol than the controls. Interestingly, in adulthood, the isoflurane-exposed rats consumed less alcohol than the controls. The scientists were not sure of the reason, but hypothesized that it may be because those rats were more anxious after being exposed to isoflurane in adolescence.
Scientists also found that anesthesia-exposed rats were in some ways able to “hold their liquor” better than their unexposed counterparts. Anesthesia-exposed rats were able to pass motor tests more easily while under the influence of alcohol as adolescents and as adults. Anesthesia-exposed adolescent rats given alcohol also socialized more while control rats given alcohol socialized less. However, when testing alcohol-induced memory impairment, adolescents who were anesthesia-exposed and then given alcohol exhibited lack of short-term memory, or a higher likelihood of a “blackout event”. Adolescent control rats given the same dose of alcohol exhibited no memory loss.
It is important to note that this study only included male rats and was focused on early-mid adolescent anesthesia exposure. This life stage is equivalent to 10-18 years in humans. This study could not be replicated in humans for ethical reasons, but suggests that a single exposure to general anesthesia during adolescence can affect how an individual responds to alcohol.
Do you like podcasts? We have one! It’s called Science Decoded. We did an episode about this study, and interviewed the lead author. Check it out here! If you don’t have Spotify, that’s totally fine. There are lots of ways to listen.