Teenagers aren't exactly known for their responsible decision making.
But some young people are especially prone to making rash, risky decisions about sex, drugs and alcohol. Individual differences in the brain's working memory — which allows people to draw on and use information to make decisions — could help explain why some adolescents are especially impulsive when it comes to sex, according to a study published Wednesday in Child Development.
"Working memory is the ability to keep different things in mind when you're making decisions or problem solving," explains Atika Khurana, an assistant professor of counseling psychology at the University of Oregon who led the study.
Khurana and her colleagues rounded up 360 adolescents, ages 12 to 15, and assessed their working memory using a series of tests. For example, the researchers told the participants a string of random numbers and asked them to repeat what they heard in reverse order.
"We basically tested their ability to keep information in mind while making decisions," Khurana says.
The researchers then tracked all the participants for two years, and asked about the teens' sexual activity. And through another series of tests and surveys, the researcher tried to gauge how likely each teen was to act without thinking, to make rash decisions and take risks.
There was a correlation between weaker working memory and the likelihood that a teen would have sex — including unprotected sex — at a younger age. And they were more likely to act without much deliberation. That trend held true even after the researchers accounted for the teenagers' age, socioeconomic status and gender.
Working memory develops throughout our childhood and adolescent years, Khurana says. But it seems this development can happen at different rates. This means some teens are more vulnerable than others to making unhealthy choices.
That's why basic sex education doesn't help all teenagers, Khurana notes. "You can give teenagers information about safe sex, but lot of times teens don't have the cognitive capacity to actually use that information and apply it in their lives."
The results add to a growing body of research that suggests that differences in teenagers' and young adults' brain development can affect their ability to make good choices, says Hugh Garavan, an associate professor of psychiatry at the University of Vermont who wasn't involved in the recent study. "But there are, of course, a lot of other factors in play. There are peer influences and personality factors. And there are genetic predispositions for impulsivity."
What scientists are still figuring out is how big a role working memory plays — and whether teenage brains can be trained to make more considered decisions.
"We know that working memory is malleable, and people can get better at it," Garavan says. Some researchers, including Khurana, are developing different activities and games that may help improve working memory. But at this point, there's little evidence to show whether these are effective.
The best parents can do try to be understanding — after all, some adolescents are biologically hardwired to act reckless, Garavan says.
The study also found that kids with very involved, engaged parents tend to make safer decisions about sex, regardless of the status of their working memories.
"So in this way, parental involvement can have a protective effect," Khurana says. "Especially for kids who have weaker working memories."