Teens who spend long hours watching television are at higher risk for depression as adults, a new study finds.

Participants faced significantly greater odds of being depressed seven years later, and the risk rose with each hour of daily television viewed, according to a report involving more than 4,000 teenagers.

The same association was found for exposure to other electronic media, the researchers noted.

"We cannot be sure it is cause-and-effect," stressed study author Dr. Brian A. Primack, an assistant professor of medicine and pediatrics at the University of Pittsburgh School of Medicine. "The reason that the study suggests it might be cause-and-effect is that the television viewing came first. It did not include people who had symptoms of depression when the study began."

His team published its findings in the February issue of the Archives of General Psychiatry.

The more than 4,100 adolescents in the study were first asked in 1995 about the number of hours they had spent the previous week watching television or videocassettes, playing computer games, or listening to the radio. They reported an average daily exposure of about 5.7 hours, including 2.3 hours of television viewing.

Seven years later, at an average age of almost 22, 308 (7.4 percent) of the young people had developed symptoms consistent with depression. The incidence of those symptoms was directly related with the number of hours of exposure to television and other electronic media reported at the start of the study, the researchers noted.

However, "while we were able to control for a lot of variables such as socioeconomic status and education, in the final analysis we cannot be sure it was cause-and-effect," Primack said.

Source: U.S. News & World Report
http://health.usnews.com/articles/health/healthday/2009/02/02/teen-tv-time-tied-to-adult-depression.html