Michael J. Cleveland, research assistant professor at the Prevention Research Center and the Methodology Center at Pennsylvania State University, and colleagues found higher levels of parental knowledge and disciplinary consistency leading to a lower likelihood of substance use.
The researchers surveyed 9,417 ninth-grade students during the spring semester, and then again the following spring semester from 27 rural school districts in Pennsylvania and Iowa.
In ninth grade, the researchers asked the students to name five of their closest friends and the researchers identified social networks within the schools by matching up the mutually exclusive friendships.
Overall, the researchers identified 897 different friendship groups, with an average of 10 to 11 students in each group.
"Among friendship groups with 'good parents' there's a synergistic effect -- if your parents are consistent and aware of your whereabouts, and your friends' parents are also consistent and aware of their (children's) whereabouts, then you are less likely to use substances," Cleveland said in a statement. "But if you belong to a friendship group whose parents are inconsistent, and your parents are consistent, you're still more likely to use alcohol. The differences here are due to your friends' parents, not yours."
The findings were published in the Journal of Studies on Alcohol and Drugs.