By Rob Hotakainen Tribune News Service

WASHINGTON – American teens are using fewer illicit drugs, with the exception of marijuana, according to a new study funded by the National Institute on Drug Abuse.

Nora Volkow, the institute’s director, says that’s good news for the nation and proof that drug prevention efforts have worked.

But she says there may be another explanation.

“The development of very, very fancy video games has resulted in a pattern of compulsive use of these games that may serve as a substitute for drug-taking,” Volkow said in an interview. “I’m speculating, but it needs to be tested.”

The study, to be released Tuesday, found that most teens preferred marijuana over tobacco and e-cigarettes in 2016.

And teens who lived in states where medical pot is legal were more likely to use marijuana edibles, researchers said.

Overall, marijuana use dipped among eighth- and 10th-graders in the last year and remained stable among seniors, the study found.

Six percent of the seniors said they use marijuana every day, while nearly 1 in 4 said they had used the drug in the last month.

By comparison, 1.8 percent of high school seniors said they smoked a half-pack of cigarettes or more every day, while 10.5 percent said they had smoked tobacco in the last month.

And e-cigarettes were slightly more popular with high school seniors, with 12.5 percent saying they had used electronic vaporizers in the past month.

The survey found a decline in the use of alcohol by teens, as well. Among seniors, 37.3 percent said they had been drunk at least once, down from the peak high of 53.2 percent reported in 2001.

Volkow said it came as a surprise that pot use had declined among eighth- and 10th-graders, especially since more states have voted to legalize either medical or recreational marijuana.

But she said it was not time to give up on prevention efforts.

“When 6 percent of high school seniors are using marijuana daily and new synthetics are continually flooding the illegal marketplace, we cannot be complacent,” she said.

Among seniors who lived in states that allowed medical pot and who reported using marijuana in the past month, 40.2 percent had consumed marijuana in food.

That compared to 28.1 percent of high school seniors who used edibles in states without medical marijuana laws.

The study, the 2016 Monitoring the Future annual survey, focused on 45,473 students in 372 public and private schools across the country.

Lloyd Johnston, the survey’s lead investigator from the University of Michigan’s Institute for Social Research, called the declining use of drugs among teens “encouraging and important.”

“But we need to remember that future cohorts of young people entering adolescence also will need to know why using drugs is not a smart choice,” he said. “Otherwise we risk having another resurgence of use as was seen in the ’90s.”

Officials said the survey, which has been taken each year since 1975, included a representative sample from all 48 U.S. contiguous states. As a result, students from Alaska and Hawaii were not included.