A new study from Pediatrics shows teenagers who spend too much surfing the internet are more likely to develop depression than teens are who categorized as normal surfers.

Researchers in Australia and China studied pathological or uncontrolled Internet use and later mental health problems in 1,041 teenage students in China. The students were free of depression and anxiety at the start of the study.

Sixty-two of the teenagers were classified at the start of the study as being moderately pathological users of the Internet, and two were found to be severely at risk for uncontrollable urges to go online.

Nine months later, the youngsters were evaluated again for anxiety and depression and 87 were judged as having developed depression. Eight reported significant anxiety symptoms.

Researchers say that their work suggests that teens who use the Internet pathologically may be about 2.5 times more likely to develop depression than  teens who are not addicted to the Internet.

Depression is common among teenagers; each year, an estimated 2 million teens and preteens develop clinical depression, and last year the federal government recommended that all teenagers be screened for depression. So parents may want to note the link between “Internet addiction” and depression, and keep a closer eye on children who depend on screen time as a pacifier or mood stabilizer. A recent study also found a correlation between video game use and ADHD. Like the “Internet addiction” study, no causal link has been proven, but one-third of children exceed the two hours of daily TV and computer screen time recommended by the American Academy of Pediatrics.