*The following is excerpted from an online article posted on HealthDay.
Over the last four decades, more American teenagers have decided to say no to drugs and alcohol, a new report shows.
"There has been a steady increase in the proportion of students graduating high school who report never having tried alcohol, marijuana, tobacco or any other drugs," said study author Dr. Sharon Levy. She directs the adolescent substance use and addiction program at Boston Children's Hospital.
For example, while about 5 percent of high school seniors had embraced abstinence in 1976, that figure had risen to 25 percent in 2014, according to the most recent poll of nearly 12,000 students.
Surveys conducted among 8th and 10th graders between 1991 and 2014 unearthed a similar trend, with abstinence jumping from roughly 25 percent to almost 60 percent among the former, and from 10 percent to more than 40 percent among the latter.
There was also a jump in total abstinence during the month leading up to each survey, rising from just over 20 percent among high school seniors in 1976 to more than 50 percent by 2014. Among 8th graders, that jump was from about 65 to about 85 percent, while among 10th graders month-long abstinence rose from about 50 to roughly 65 percent, the findings showed.
Levy said the downward trends didn't catch her off-guard, even if "the findings may surprise people because we constantly hear bad news about drug use and the opioid epidemic."
She explained that both drinking and smoking -- the number one and number three most common substance use habits -- have been sliding in popularity across the board for a while now, even though pot use has held steady.
But why? That remains "the million dollar question," said Levy, "and for sure it doesn't have one simple answer."
Overall, she credited public health efforts for giving rise to a new cultural climate that encourages teens to shun substance use because it's dangerous and unhealthy, rather than because it's immoral or forbidden.
Still, Levy warned that the good news "is quite precarious."
For example, "while fewer teens overall are using substances, those who do face a landscape of more dangerous substances [like opioids] compared to their parents' generation," Levy said.
Investigators also found that white and Hispanic teens were less likely to choose abstinence, compared with their black peers. And because girls are more likely than boys to "misuse" prescription drugs -- particularly pain medications -- they were also less likely to be fully abstinent, despite less frequent alcohol, marijuana and tobacco use.
"This is a good reminder that parents, primary care providers and other trusted adults should be talking to kids about avoiding prescription medications, knowing how addictive they can be," Levy said.
What's more, she stressed that "there are always lurking threats to our progress." In particular, Levy pointed to the soaring popularity of e-cigarettes and the steadfast appeal of marijuana, both of which are increasingly perceived as safe.
The study findings were published online in the journal Pediatrics.