Philadelphia Police Officer Wendy McGrody began a recent fifth-grade DARE lesson at Cramp Elementary in the Kensington/Fairhill neighborhood by navigating some tough questions. "If someone has an overdose, can they come back?" one student asked.

"When you overdose, your body technically shuts down, and you can die from it," McGrody answered. "Unfortunately, as you've been noticing in the news, there are a lot of people losing their lives because of heroin."

Javier Rodriguez, 11, said later that this knowledge made him "nervous." Daniel Cruz, 11, said he appreciated the fact that the police officer was "truthful." Emmorie Frazier, also 11, said that McGrody "likes kids. I can tell she likes her job."

One of the strengths of the DARE (Drug Abuse Resistance Education) program, in fact, seems to be the relationships that students develop with officers over 10 weekly lessons. DARE has come a long way from the 1980s and '90s, when it smacked of Nancy Reagan's "Just Say No" campaign, which was widely derided as being ineffective. Now, based partly on Pennsylvania State University research, the elementary and middle school curriculum uses "keepin' It REAL," interactive lessons that teach decision-making and other skills based on the four ways that teens turn down drugs: Refuse, Explain, Avoid and Leave.

Programs that emphasize emotional regulation and social skills may keep some kids from experimenting, said Kathleen Meyers, who studies prevention programs at the Treatment Research Institute in Philadelphia.

Teen drug use is in decline, with the exception of marijuana use, which seems to have flattened out, according to a 2016 survey funded by the National Institutes of Health.

"But there are still kids who are susceptible," said Dan Romer, research director of the University of Pennsylvania's Annenberg Public Policy Center. Because the majority of people with substance-use disorders began using during adolescence, experts continue to try to improve prevention education.

Not all prevention programs are backed by research. Many are one-size-fits-all, offered only in lower grades, if at all. New research suggests that high school is an important period. Recent studies also indicate that programs should identify kids who are at higher risk for addiction.

Teenage brains are still developing – and continue to evolve into their 20s, a bit like soft plaster slowly hardening. "This gives a special urgency to keeping kids away from alcohol and drugs during this period of plasticity," said Temple psychology professor Laurence Steinberg, author of Age of Opportunity: Lessons from the New Science of Adolescence.

One popular curriculum, cited as"evidence-based" by a 2016 surgeon general's report on addiction, was developed by a Cornell psychologist more than 30 years ago to discourage middle-schoolers from smoking. LifeSkills Training has since ballooned into an overall prevention program.

Surveys of eighth graders in Pennsylvania's Somerset and Cambria Counties have found drops of more than 50 percent in binge drinking since it was implemented in 2011 – "an overwhelming result," said Ronna Yablonski, executive director of the Cambria County Drug Coalition.

A recent study in the journal Addiction suggests that more needs to be done.

Researchers followed nearly 400 Philadelphia-area children for eight years beginning at ages 10 to 12. They found that those who combined alcohol, tobacco, and marijuana during adolescence were more likely to become addicted. Children with impulse-control issues and weak working memory were at a higher risk.

"The first thing that comes into mind dominates their thinking," said Annenberg's Romer, a coauthor. If those kids try to enjoy drugs, they can become a preoccupation. Targeting them with a specific curriculum before that happens, perhaps based on confidential screenings, might be key to improving prevention, Romer said.

A new program piloted in Canada is treading this path. Preventure trains educators to administer screenings at the start of the school year that will find students who display any of four personality traits – sensation-seeking, impulsivity, anxiety sensitivity, or hopelessness – linked to high-risk behavior. Those who do will attend workshops based on their profiles that use specific techniques and therapies for teaching them how to combat their vulnerabilities.

"We don't really talk about drugs and alcohol at all," said University of Montreal psychiatry professor Patricia Conrod, who created Preventure. "It's all targeting underlying risk factors."

Five international studies found major decreases in participants' binge drinking and use of marijuana and cocaine. Researchers also found a smaller ripple effect among students who were not part of the program, perhaps because recreational drug use is a social activity during adolescence.

Preventure, which isn't currently available anywhere in the United States, goes far beyond most prevention programs.

"Drug education is easier for people to do, and then that's not even that easy," Conrod said. "And this program is a lot heavier. It involves people taking responsibility and being willing to engage in these very difficult conversations with kids – talking about kids' depressive thoughts and how they're coping with them."

Meanwhile, Officer McGrody is having at least some of those difficult conversations in Kensington. Deanda Logan, principal of Cramp Elementary, thinks the DARE lessons help.

"Our children are very curious and will ask a lot of questions," Logan said in an interview.  "And to have a police officer who's friendly, who's here to support them, I think that's a powerful message."

The National Institute on Drug Abuse puts out a research-based guide on principles of adolescent substance-use disorder treatment. It notes that adolescents can benefit from a drug-abuse intervention even if they are not addicted to a drug.