Teenagers with unhealthy online habits may be at greater risk of depression, new findings from China hint.

While the study isn’t proof of a causal link, it is the first to approach the question of whether some forms of Internet use might trigger mental health problems down the road, according to the authors.

They rounded up more than 1,000 high school students in the city of Guangzhou and had them fill out two sets of questionnaires, spaced nine months apart, about their mental health and Internet use.

Among the 1041 students who had no signs of anxiety and depression at the outset, those who reported “unhealthy” Internet use were two and a half times as likely to have symptoms of depression at the second evaluation.

“This result suggests that young people who are initially free of mental health problems but use the Internet pathologically could develop depression as a consequence,” Lawrence T. Lam, of the University of Notre Dame Australia in Darlinghurst, and Zi-Wen Peng, of SunYat-Sen University in Guangzhou, write in the Archives of Pediatrics and Adolescent Medicine.

They define “pathological” Internet use according to Young’s Internet Addiction Scale, which includes 20 questions such as “How often do your grades or school work suffer because of the amount of time you spend on-line?” and “How often do you fear that life without the Internet would be boring, empty, and joyless?”

About six percent of the Chinese students were labeled as having “moderate” pathological Internet use, and two landed in the “severe” category.

Eight percent of the teenagers developed symptoms of depression over the course of the study, and those with “bad” online habits were at greatest risk. There was no link between Internet use and anxiety.

Although the study tested Internet habits that came before the symptoms of depression, it can’t say whether other psychological problems also played a role. For instance, a kid feeling slightly isolated might spend more time online, which could then fuel the sense of isolation.

Still, Dr. David A. Gorelick, who was not involved in the research, said the study had a strong design.

“It might lead mental health professionals and even parents to think more closely about the possible effect of pathologic Internet use in teenagers,” Gorelick, a psychiatrist with the National Institute on Drug Abuse in Baltimore, told Reuters Health.

From his work with adult substance abusers, Gorelick said addiction often causes addicts’ social lives to collapse, which might lead to depression. The same could be true for behavioral addictions, such as pathologic gambling, which are increasingly recognized by psychiatrists.

“As you get caught in the addiction, your behavior and thoughts start to focus on drug seeking and drug taking, and you start to neglect your other social responsibilities,” Gorelick said.

In his opinion, excessive Internet use could be “an early warning” that something is wrong. But he stressed that “Internet addiction” is still an unproven concept.

“There have been so few studies that we just don’t know if the phenomenon exists,” Gorelick said.

SOURCE:  Archives of Pediatrics and Adolescent Medicine, October, 2010.