Teens who drink, smoke cigarettes or use marijuana by themselves are more likely to have health and behavioral problems as young adults than those who do the same things with others, researchers reported Thursday.
The findings stem from a nine-year study of about 6,000 adolescents from California and Oregon who were involved in a drug prevention campaign for middle-school students. They were asked while in middle school and high school and at age 23 about their substance use and other issues.
Those who drank, used marijuana or smoked while alone were less likely to graduate from college, more likely to have substance-use problems as young adults and reported poorer physical health by age 23 than those who used the substances with other people, the study found.
The solitary substance users also reported more delinquent behavior such as stealing and acting out at school, and spent more time at parties and dating than peers who used the substances in social settings, the study found.
The findings by researchers with the nonprofit research organization RAND Corp. appeared in the journal Psychology of Addictive Behaviors.