Students from lower-income neighborhoods who attended one of five high-performing Los Angeles County high schools were less likely to abuse marijuana than those who weren’t offered admission, UCLA researchers found.

Admission to the public schools was based on a random lottery system, which is designed to equalize applicants’ chances of being admitted. For the study, the researchers surveyed 1,270 students who had applied to at least one of the five schools in fall 2013 or fall 2014, and collected data from 2013 through 2017.

Students were asked in the surveys whether they used marijuana, and how frequently, from 9th through 11th grade. Those who were offered admission to or attended any of the five schools were less likely to misuse marijuana, had fewer peers who abuse drugs, spent more time studying, and were less likely to skip school.

The correlation between attending one of the schools and marijuana abuse was particularly consistent for boys. By 11th grade, boys who attended one of the schools were 50% less likely to abuse marijuana than their counterparts who weren’t offered admission.

“We concluded that schools play an important role in influencing adolescent behavior,” said the study's first author, Dr. Rebecca Dudovitz, an assistant professor at the David Geffen School of Medicine at UCLA and pediatrician at UCLA Mattel Children’s Hospital. “Investing in schools offers a tool for improving teen health.”

The schools analyzed in the study were considered high performing because their students’ performance on 2012 California standardized tests placed them in the top one-third of Los Angeles County schools. Each of the five schools also served primarily economically disadvantaged students and had more applicants for admission than slots available. Of the students surveyed, 694 were admitted to at least one school, and 576 were not; 52.6% of the students were female and 47.4% were male.

Although prior research has documented a link between a supportive school environment and health behaviors, the UCLA study is the first to use a random lottery to analyze the effects of students transitioning to a high-performing high school and to present detailed data on school environments and social networks.

The study is published today in JAMA Pediatrics; it was funded by the National Institute on Drug Abuse.