Your friend’s Facebook addiction is in the genes—namely a mutation that German researchers say is linked to excessive Internet use.
Researchers from the University of Bonn and the Central Institute of Mental Health in Mannheim identified the mutation as the T-variant (CC genotype) of the rs1044396 polymorphism on the cholinergic receptor, nicotinic, alpha 4 (CHRNA4) gene. The variant also is key in promoting nicotine addiction by changing the genetic makeup for the Alpha 4 subunit on the nicotinic acetylcholine receptor. As with nicotine from tobacco, acetylcholine acts as a neurotransmitter playing a key role in activating the brain's reward system.
The research team interviewed 843 people, of which 132 patients admitted to problematic online behavior; their thoughts, for example, revolved around the Internet during the day. Those patients provided DNA samples and completed an Internet Addiction Test Questionnaire.
The mutation “occurred significantly more frequently” in most of the 132 patients, the team concluded in findings published yesterday in Journal of Addiction Medicine.
"It was shown that Internet addiction is not a figment of our imagination," the study’s lead author Christian Montag, Ph.D, from the Department for Differential and Biological Psychology at the University of Bonn, said in a statement. “There are clear indications for genetic causes of Internet addiction.”
Women appeared more prone to the mutation than men, though researchers emphasized that more study is needed since previous research has found that men were more prone to Internet addiction. "The sex-specific genetic finding may result from a specific subgroup of Internet dependency, such as the use of social networks or such," Dr. Montag said in the statement.
Dr. Montag also acknowledged that studies involving larger groups of patients would also be needed to further analyze the connection between Internet addiction and the mutation, which has led to the discovery of a biological marker allowing for a neuroscientific characterization of online addiction.