Should the Drinking Age Be Lowered from 21?

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We asked Dr. H. S. Swartzwelder, frequently cited expert on adolescent brain development and substance abuse, MADD consultant, and Choose Responsibility board member to respond to this question.

“It is true that the brain continues to develop into a person’s 20s, particularly the frontal lobes which are critical for many of the higher cognitive functions that are so important for success in the adult world—such as problem solving, mental flexibility, and planning.  

“It is also clear that alcohol affects the adolescent brain differently than the adult brain, but the story is not simple and the data should be interpreted cautiously as this complex science continues to evolve. Although alcohol affects some brain functions more powerfully during adolescence, it affects other functions less powerfully during the same period. For example, studies in animals clearly indicate that a single dose of alcohol can impair learning (and learning-related brain activity) more powerfully in adolescent animals than in adults. But on the other hand a somewhat higher dose will produce far greater sedation (and sedation-related brain activity) in adult animals than in adolescents. So, in terms of single doses of alcohol, the adolescent brain is not uniformly more or less sensitive to alcohol—it depends on the brain function that is being measured. Importantly, there has been little direct study of the effects of acute doses of alcohol on adolescent humans, compared to adults. One study found that a single dose of alcohol resulting in blood alcohol levels near 80mg/dl (the legal limit) impaired learning more powerfully among people in their early 20s than it did in people in their late 20s, but it will take more research to answer this question with authority in human subjects.

 
“Since the effects of single doses of alcohol can have markedly different effects on adolescents than on adults, it makes sense to ask whether this means that the adolescent brain is more or less sensitive to the effects of repeated doses of alcohol over time. In my view, the jury remains out on this question, but there are some studies in animals which suggest that the adolescent brain may be more vulnerable to long-term damage by alcohol than the adult brain. Similarly, there are some studies of humans who consumed large quantities of alcohol over extended periods of time during adolescence, and have relatively small hippocampi (a brain region critical for certain types of learning). All of these studies need to be fleshed out before the issue is settled, but, if nothing else, they give teens a very good reason to think carefully about drinking to excess…and this is probably the pivotal issue—how much is too much?  

“Most studies of the effects of chronic alcohol exposure in adolescence, compared to adulthood, have focused on relatively high doses. Studies of lower doses, and less severe chronic dosing regimens, will be needed to determine whether the adolescent brain is more sensitive to the long-term effects of mild to moderate drinking. There are plenty of studies indicating that early, unsupervised drinking can lead to trouble for teens—both immediately and down the road.   But this does not mean that an 18 year-old who has a beer or two every couple of weeks is doing irreparable damage to her brain. It is the 18 year-old (or 30 year-old, for that matter!) who downs five or six drinks in a row on his way to a dance that worries me.”