Adolescents who are addicted to the internet are more likely than non-addicted teens to engage in self-injurious behaviors like hitting themselves, pulling their own hair, or pinching or burning themselves, according to a study released Thursday.

Researchers surveyed 1,618 adolescents between 13 and 18 years old from the Guangdong Province in Southeast China about their self-injurious behaviors and gave them a test designed to gauge internet addiction.

While only about 10 percent of the students surveyed were moderately addicted to the internet, and less than 1 percent were severely addicted, those students were 2.4 times more likely to have self-injured one to five times in the past 6 months than students with normal internet habits, Dr. Lawrence T. Lam from University of Notre Dame, Darlinghurst, New South Wales, Australia, and colleagues found.

Additionally, the moderately-to-severely internet-addicted students were almost five times more likely than non-addicted students to have self-injured six or more times in the past 6 months, they report in the journal Injury Prevention.

The link between internet addiction and self-injurious behavior in adolescence remained “strong and significant” after the researchers accounted for other variables that have been previously associated with self-injury, including depression, family dissatisfaction, or stressful life events, suggesting that internet addiction is an independent risk factor for self-injurious behavior.

Since the mid 1990s, internet addiction has been classified as a mental health problem with symptoms similar to other addictions. Experts interpret internet addiction, among other things, as feelings of depression/nervousness/moodiness when not online, which only go away when the addict gets back online. Fantasizing or being preoccupied about being online are other signs of internet addiction.

Lam urges parents to be on the look out for signs of internet addiction. Internet addiction, Lam told Reuters Health, may not simply be a matter of time spent in front of a computer screen.

“To assess whether a young person is using the internet excessively,” Lam noted, “we still have to look into other signs and symptoms. For example, if someone feels an urge to get online to check the email or visit any sites, knowing that he or she has just checked the mail two minutes ago, then I would say that exhibits an addictive symptom.”

While acknowledging that self-injurious behavior is linked to borderline personality disorder, Lam and colleagues seem to favor the idea that internet addiction and self-injury are both manifestations of impulse control disorders.

Source: Injury Prevention 2009:15; 403-408.