Sarah Wiehe
assistant professor of pediatrics
IU School of Medicine

There are hundreds of millions of cell-phone subscribers in the United States, and it?s a good bet that a sizable and growing chunk of those subscribers are teenagers. So it makes sense that researchers are turning to that ubiquitous teen accessory as they try to track the relationship of teenagers? activities to potentially harmful health-related behaviors such as smoking or sexual activity.

In a paper published in the Journal of Adolescent Health, researchers from the Indiana University School of Medicine reported on a pilot study that evaluated the feasibility of using cell phones equipped with global positioning systems (GPS) to track where 14- to 16-year-old girls spend their time.

"We didn't know if the kids would take the cell phones with them or would leave them at home," says Sarah Wiehe, an assistant professor of pediatrics at the IU School of Medicine and a scientist affiliated with the Regenstrief Institute. "But they did carry the phones, and the GPS data revealed that they were spending more time away from home, school, and surrounding areas than anticipated."

The girls traveled the farthest from home in the evenings on weekends or holidays. The greatest percentage of time spent more than 1 kilometer (.62 miles) away from home was also during these times. The GPS technology was also useful for teens who didn't wander as far by showing more detailed information on where they spend time inside their neighborhoods.

This information on teen travel patterns is important, Wiehe points out, because previous studies that have looked at the effect of environment on teens have focused only on home, school and nearby areas.

Wiehe explains that although researchers know that a teenager's environment has an influence on his or her health, they don't have a very clear idea of why this association exists.

"What in the environment is contributing to behavior choices such as drug use? With GPS we know where the teens are and when they are there, but we don't know what they are doing. Now that we know the technology works, that the girls took their phones with them, we need to learn the characteristics of the environments in which they find themselves," says Wiehe.

Based on the success of the initial project, which was supported by the IU School of Medicine, the researchers have received funding from the Robert Wood Johnson Foundation to enroll 160 urban teenage girls in a study to track their movements in spring, summer, fall, and winter. They hope to learn much more about how teenage girls interact with their many environments in ways that affect their health.

"We are at the tip of the iceberg when it comes to seeing where and how teens spend time. As a doctor charged with keeping kids healthy, I am hoping our studies will result in interventions," says Wiehe. Those interventions might be as simple as text messages promoting healthy behavior sent at the time when teenagers are most likely to take a health risk. Or maybe "something we haven't even thought of yet that will encourage good choices," says Wiehe.

Wiehe's co-authors on the study include Shawn C. Hoch and Jeffery S. Wilson of the Department of Geography at Indiana University - Purdue University Indianapolis; Gilbert C. Liu and Aaron E. Carroll of the IU School of Medicine and Regenstrief Institute; and J. Dennis Fortenberry of the IU School of Medicine.