Females who identify as sexual minorities may face an increased risk of substance use that shows up as early as age 13, researchers said.

The pattern of increased substance use for youth who identify as sexual minorities is magnified significantly for females, according to a study published in the Journal of LGBT Youth.

“We saw this striking difference in substance use at age 13 and there was a rapid increase in the rate of cigarette and alcohol use over time,” said study lead author Sarah Dermody, Assistant Professor in Oregon State University in the US.

The researchers also noted that early adolescence is a critical period for prevention and intervention efforts.

For the study, 2,200 urban girls (heterosexual as well as those identifying as lesbian/gay or bisexual) were studied for substance use from age 13 to 20.

The researchers found that disparities in substance use between heterosexual and sexual minority girls were already present at age 13 and the difference in substance use increased as they entered their 20s.

“The findings suggest that early prevention and intervention efforts may be needed to reduce initial use and slow the escalation of substance use among the population,” Dermody said.