LOS ANGELES — Teenagers who see friends smoking and drinking alcohol in photographs posted on Facebook and Myspace are more likely to smoke and drink themselves, according to a new study from the University of Southern California (USC).
"Our study shows that adolescents can be influenced by their friends' online pictures to smoke or drink alcohol," said Thomas W. Valente, Ph.D., professor of preventive medicine at the Keck School of Medicine of USC and the study's principal investigator. "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 appears in the Sept. 3, 2013, online edition of the Journal of Adolescent Health.
Valente and his team surveyed 1,563 10th-grade students from the El Monte Union High School District in Los Angeles County in October 2010 and April 2011 about their online and offline friendship networks and the frequency of their social media use, smoking and alcohol consumption. At the time of the study, El Monte was the ninth largest city in the county, with a population of about 113,500.
The researchers found that the size of one's online network of friends was not significantly associated with risky behavior. Exposure to friends' online pictures of partying or drinking, however, was significantly associated with both smoking and alcohol use. Teens whose close friends did not drink alcohol were more likely to be affected by increasing exposure to risky online pictures.
"The evidence suggests that friends' online behaviors are a viable source of peer influence," said Grace C. Huang, Ph.D., MPH, a graduate of the Keck School of Medicine of USC's Health Behavior Research program and the study's first and corresponding author. "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."
Students who responded to the survey were evenly distributed across gender and on average 15 years old. About two-thirds were Hispanic/Latino and about one-fourth were Asian, which closely reflects the ethnic distribution of El Monte. In April 2011, nearly 30 percent of respondents had smoked and more than half had at least one drink of alcohol. Roughly one-third of students reported having at least one friend who smoked and/or consumed alcohol.
Almost half of all students reported visiting Facebook and Myspace regularly. Between October 2010 and April 2011, Facebook use (75 percent) increased while Myspace use (13 percent) decreased. On average, 34 percent of students had at least one friend who talked about partying online and 20 percent reported that their friends posted party/drinking pictures online.
In line with earlier studies, the researchers observed differences between Facebook and Myspace users. Facebook-only users had higher grades, spoke more English at home and were more likely to have a higher socio-economic status. They were less likely to be Hispanic and less likely to have ever smoked or drank alcohol. While Facebook use did not seem to affect smoking or drinking, the study found that higher levels of Myspace use was associated with higher levels of drinking.
Further research might examine how online and offline friendships differ in terms of activities and interactions they have with each other, Huang said.
"Little is known about how social media use affects adolescent health behaviors," said Huang, who now is a post-doctoral fellow at the 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."
The study was supported by the National Institute on Alcohol Abuse and Alcoholism (1RC1AA019239-01) and National Cancer Institute (T32 CA-009492028). Co-authors include Jennifer B. Unger, Ph.D.; Daniel Soto, MPH; Kayo Fujimoto, Ph.D.; Mary Ann Pentz, Ph.D.; and Maryalice Jordan-Marsh, Ph.D.
Huang, G.C., Unger, J.B., Soto, D., Fujimoto, K., Pentz, M.A., Jordan-Marsh, M., & Valente, T.W. (2013). Peer influences: The impact of online and offline friendship networks on adolescent smoking and alcohol use. Journal of Adolescent Health. Published online Sept. 3, 2013; doi: 10.1016/j.jadohealth.2013.07.001
ABOUT KECK MEDICINE OF USC
Keck Medicine of USC is the University of Southern California's medical enterprise, one of only two university-owned academic medical centers in the Los Angeles area. Encompassing academic, research and clinical entities, it consists of the Keck School of Medicine of USC, one of the top medical schools in Southern California; the renowned USC Norris Comprehensive Cancer Center, one of the first comprehensive cancer centers established in the United States; the USC Care faculty practice; the Keck Medical Center of USC, which includes two acute care hospitals: 411-bed Keck Hospital of USC and 60-bed USC Norris Cancer Hospital; and USC Verdugo Hills Hospital, a 158-bed community hospital. It also includes outpatient facilities in Beverly Hills, downtown Los Angeles, La Cañada Flintridge, Pasadena, and the USC University Park campus. USC faculty physicians and Keck School of Medicine departments also have practices throughout Los Angeles, Orange and Riverside counties.
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