Elizabeth Armstrong Moore/CNET

Internet addiction is real, researchers out of the University of Bonn say, and its source can be explained at the molecular level.

Researchers from the school's departments of psychology and neuroscience report in the September 2012 issue of the Journal of Addiction Medicine that a simple variation on the CHRNA4 gene results in a significantly higher prevalence of Internet addiction -- and particularly in women.

"Internet addiction is not a figment of our imagination," lead author Christian Montag says in a news release. "The current data already shows that there are clear indications for genetic causes of Internet addiction... If such connections are better understood, this will also result in important indications for better therapies."

The researchers interviewed 843 people about their Internet habits and found that 132 of them exhibited "problematic behavior in how they handle the online medium," so much so that "all their thoughts revolve around the Internet during the day, and they feel their well-being is severely impacted if they have to go without it."

Using DNA samples, they then compared the genetic makeup of these men and women to that of a control group, and found that the problematic group more often carried this genetic variation, which has also been linked to nicotine addiction.

As Montag explains it, nicotine from tobacco fits like a key into this receptor and activates the brain's reward system, and the Internet appears to play a similar role. He adds that larger studies should be carried out to further investigate this connection, because beyond simply validating it, understanding the mechanism could improve future therapies.