THURSDAY, Sept. 5 (HealthDay News) -- When it comes to photos of risky behavior posted on friends' social networking sites, it seems that what teenagers see, teenagers do, new research shows.
A study conducted by researchers at the University of Southern California found that when teens see pictures of their friends drinking alcohol or smoking on sites like Facebook and Myspace, they are more likely to drink or smoke themselves.
"Our study shows that adolescents can be influenced by their friends' online pictures to smoke or drink alcohol," principal investigator Thomas Valente, a professor of preventive medicine at the Keck School of Medicine at USC, said in a university news release. "To our knowledge, this is the first study to apply social network analysis methods to examine how teenagers' activities on online social networking sites influence their smoking and alcohol use."
The study, published online Sept. 3 in the Journal of Adolescent Health, involved nearly 1,600 male and female 10th-grade students from a school district in Los Angeles County. About two-thirds of the participants were Hispanic and about 25 percent were Asian.
The students, average age 15 years, were surveyed in 2010 and 2011 about their online and offline friendship networks. They were also asked how often they used social media sites, smoked and drank alcohol.
The investigators found that at the end of the study period, nearly 30 percent of the students had smoked and more than 50 percent had had at least one alcoholic drink. In addition, about one-third of students had at least one friend who smoked, consumed alcohol, or both.
Although the number of "friends" the teens had in their online networks was not considerably associated with their risky behavior, the researchers did find that exposure to friends' online photos of partying or drinking was significantly linked to both smoking and drinking. They noted that teens whose close friends did not drink were more likely to be influenced by exposure to risky behavior in photos posted online.
"The evidence suggests that friends' online behaviors are a viable source of peer influence," study first author Grace Huang, a graduate of the Keck School of Medicine of USC's Health Behavior Research program, said in the news release. "This is important to know, given that 95 percent of 12- to 17-year-olds in the United States access the Internet every day, and 80 percent of those youth use online social networking sites to communicate."
Nearly 50 percent of all the students reported visiting Facebook and Myspace on a regular basis. Between October 2010 and April 2011, Facebook use increased 75 percent, while Myspace use decreased 13 percent. On average, about one-third of the students had at least one friend who posted online messages about partying, and 20 percent said they had friends that posted pictures of partying or drinking.
The researchers pointed out, however, there were some differences between Facebook and Myspace users. Those who only used Facebook tended to have higher grades, speak more English at home and were more likely to have a higher social and economic status. These Facebook-only users were also less likely to be Hispanic and less likely to have ever smoked or have had an alcoholic drink.
Although Facebook use did not apparently affect smoking or drinking, the researchers found that greater Myspace use was associated with more drinking.
"Little is known about how social media use affects adolescent health behaviors," concluded Huang, who now is a post-doctoral fellow at the U.S. National Cancer Institute. "Our study suggests that it may be beneficial to teach teens about the harmful effects of posting risky behaviors online and how those displays can hurt their friends."
Although the study found an association between viewing online photos of risky behaviors and smoking and drinking among teens, it did not prove a cause-and-effect relationship.
The American Academy of Pediatrics has more about social media and kids.