WEDNESDAY, June 4 (HealthDay News) -- Alcoholics Anonymous and Narcotics Anonymous offer benefits to adolescents, even if they eventually stop attending meetings, says a study that included 160 teens enrolled at two treatment centers in California.

The teens, with an average age 16, stayed from four to six weeks at the centers, which were focused on abstinence and used a 12-step model. The teens were reassessed at six months, and one, two, four, six, and eight years after they left the centers.

"We found that most of the youth attended at least some AA/NA meetings post-treatment," John F. Kelly, associate director of the MGH-Harvard Center for Addiction Medicine at Massachusetts General Hospital, said in a prepared statement.

"Those patients with severe addiction problems and those who believed they could not use alcohol/drugs in moderation attended the most. The NA and AA focus on abstinence/recovery probably resonates better with these more severely dependent individuals who also typically need ongoing support," said Kelly, who's also an assistant professor in psychiatry at Harvard Medical School.

While many of the study participants eventually stopped going to AA/NA meetings, they seemed to benefit from their time with the organizations.

"We found that patients who attended more AA and/or NA meetings in the first six months post-treatment had better longer term outcomes, but this early participation effect did not last forever -- it weakened over time," Kelly said.

"The best outcomes achieved into young adulthood were for those patients who continued to go to AA and/or NA. In terms of a real-world recovery metric, we found that for each AA/NA meeting that a youth attended, they gained a subsequent two days of abstinence, independent of all other factors that were also associated with a better outcome."

Kelly noted that even a little exposure to AA/NA can go a long way.

"During the first six months post-treatment, even small amounts of AA/NA participation -- such as once per week -- was associated with improved outcome, and three meetings per week was associated with complete abstinence. This suggests youth may not need to attend as frequently as every day, sometimes recommended clinically, to achieve very good outcomes," Kelly said.

The study was published online in the journal Alcoholism: Clinical and Experimental Research and was expected to be in the August print issue.

More information

The Nemours Foundation has more about teens and alcohol.