Protects young adult brains from alcohol use

with citations
A more recent argument advanced in favor of the 21 year-old drinking age is that the adolescent brain is affected differently by alcohol. A drinking age of 21, the logic goes, will lead to a healthier population by keeping alcohol out of the hands of those it can harm the most. Brain scans and measurements of alcohol affected areas of the brain in young adolescents with alcohol abuse disorders show lower rates of brain activity during memory tasks and less developed brain structures than in non-drinking peers.

However . . .

When these groups argue that the vulnerable period of adolescence ends around the age of 20 they are not taking into account that, in the field of neurology, adolescence does not end until around the age of 25. Thus, even if the current drinking age was keeping young adults from drinking, it would still not have the protective factor that its advocates claim. Moreover, exactly how alcohol’s effects are differentially felt by the adolescent brain versus the adult brain, though increasingly scrutinized, is less clear. As a result, when drinking age 21 advocates do stress the harm associated with drinking, those claims tend to be conveniently overstated. The truth is in the only study that we’ve been able to find that compares drinkers who started drinking either after 21 or before 21, but still controls for years of drinking and quantity of consumption, researchers found the two groups to be indistinguishable in terms of long-term cognitive impairments.