New research indicates that even moderate drinking by adolescents on a regular basis can cause potentially lasting changes to the part of the brain that affects memory. 

Much of the previous research focused on behavioral effects of alcohol consumption. The new study looked at long-term effects of “intermittent” drinking on the circuitry of an adolescent brain.

The study investigated the biological mechanisms behind these long-term effects, says Scott Swartzwelder, the lead scientist on the new study, published Monday in the journal Alcoholism: Clinical & Experimental Research, and a professor of psychiatry at Duke University in Durham, N.C.

Dr. Swartzwelder is careful to say “adolescent” instead of “teen.” As a society, we think that adolescence is over once someone hits 18, he says. But from a neuroscientist’s perspective, the brain isn’t fully developed until age 25 and can exhibit these negative effects of alcohol consumption until then, he says.

Dr. Swartzwelder’s team gave rats 10 doses of alcohol over their 16-day period of adolescence in a roughly “two days on, two days off” pattern that imitates how adolescents drink intermittently, he says. The rats were given doses that were the equivalent of “maybe a solid five drinks” for humans, not enough to cause them serious impairment, Dr. Swartzwelder says.

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