According to a study conducted by Catriona M. Morrison from the Institute of Psychological Sciences in the University of Leeds, teens who are internet addicts are twice as likely to develop depression. The study which was published in Psychopathology tests a group of 1,100 young people aged 13 to 18 years old who were engaged in pathologic internet use. These young people experienced an adjusted incidence rate ratio for depression of 2.5 (95% CI 1.2 to 4.3).

The tested young people had no reported depression nine months prior to being part of the group. It would seem that as these young people developed internet addiction, they also developed a predisposition towards depression.

Researchers have been theorizing since the mid 1990's that excessive internet use is no different from other addictions. The questions used during the study included self-rating scales for depression as well as questions related to determining how addicted a person is to the internet. The baseline responses showed that 6.2% of the subjects were moderately addicted and .2% had severe internet addiction. Addicted subjects were more likely to use the Internet for entertainment (gaming, viewng sexually gratifyng websites, joining online communities and/or chatrooms) rather than for finding information or communicating with other people.

During follow-up, majority of the .2% that were severely addicted showed significant symptoms of anxiety. At least 8.4% scored 50 on the depression scale.

"The Internet now plays a huge part in modern life, but its benefits are accompanied by a darker side," said Dr. Catriona Morrison. "While many of us use the Internet to pay bills, shop and send emails, there is a small subset of the population who find it hard to control how much time they spend online, to the point where it interferes with their daily activities."

What the study could not rule out, however, was the possibility that the teens' incipient depression was what made them predisposed to internet addiction.