WEDNESDAY, Oct. 25, 2017 (HealthDay News) -- As substance abuse has declined among American teens, so have behavioral issues tied to criminal violence, a new study shows.
The researchers analyzed data from more than 210,000 teens, 12 to 17 years old, who took part in an annual federal government survey from 2003 to 2014.
During that time, abuse of alcohol, nicotine and illegal drugs by teens fell 49 percent. At the same time, behavioral problems -- such as fighting, assault, stealing, selling drugs or carrying a handgun -- dropped 34 percent, according to the study by researchers at the Washington University School of Medicine in St. Louis.
"We've known that teens overall are becoming less likely to engage in risky behaviors, and that's good news," said study author Richard Grucza, a professor of psychiatry.
"But what we learned in this study is that the declines in substance abuse are connected to declines in delinquency," he said in a university news release. "This suggests the changes have been driven more by changes in adolescents themselves more than by policies to reduce substance abuse or delinquent behavior.
"It's not clear what is driving the parallel declines," Grucza said. "New policies -- including things like higher cigarette taxes and stricter anti-bullying policies -- certainly have a positive effect. But seeing these trends across multiple behaviors suggests that larger environmental factors are at work. These might include reductions in childhood lead exposure, lower rates of child abuse and neglect and better mental health care for children."
Heroin and opioid abuse among adults have become epidemic in many parts of the country, but teens' use of these drugs has fallen, the study found.
"Opioid problems continue to increase among adults," Grucza said. "But among the 12- to 17-year-old population, we saw a drop of nearly 50 percent."
Based on the data from the survey, the annual U.S. National Survey on Drug Use and Health, the researchers estimated that the number of teens with substance abuse disorders fell by nearly 700,000 from 2003 to 2014.
Because a person can be addicted to nicotine while abusing alcohol or marijuana, the researchers estimated that the total number of substance-use disorders among teens fell by about 2 million.
The study was published Oct. 25 in the journal Psychological Medicine.
The U.S. National Institute on Drug Abuse offers resources for teens.