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Dopamine Genes and Reward Dependence in Adolescents with Excessive Internet Video Game Play

Han, Doug Hyun MD, PhD; Lee, Young Sik MD, PhD; Yang, Kevin C. BA; Kim, Eun Young MD, PhD; Lyoo, In Kyoon MD, PhD; Renshaw, Perry F. MD, PhD

doi: 10.1097/ADM.0b013e31811f465f
Original Article

Excessive internet video game play (EIGP) has emerged as a leading cause of behavioral and developmental problems in adolescents. Recent research has implicated the role of striatal dopaminergic system in the behavioral maladaptations associated with EIGP. This study investigates the reward-dependence characteristics in EIGP adolescents as it potentially relates to genetic polymorphisms of the dopaminergic system and temperament. Seventy-nine male EIGP adolescents and 75 age- and gender-matched healthy comparison adolescents were recruited. Associations were tested with respect to the reward-dependence (RD) scale in Cloninger’s Temperament and Character Inventory and the frequencies of 3 dopamine polymorphisms: Taq1A1 allele of the dopamine D2 receptor (DRD2 Taq1A1) and Val158Met in the Catecholamine-O-Methyltransferase (COMT) genes. The Taq1A1 and low activity (COMTL) alleles were significantly more prevalent in the EIGP group relative to the comparison group. The present EIGP group had significantly higher RD scores than controls. Within the EIGP group, the presence of the Taq1A1 allele correlated with higher RD scores. Our findings suggest that EIGP subjects have higher reward dependency and an increased prevalence of the DRD2 Taq1A1 and COMTL alleles. In particular, the DRD2 Taq1A1 allele seems to be associated with reward dependence in EIGP adolescents.

From McLean Hospital Brain Imaging Center and Department of Psychiatry (DHH, KCY, IKL, PFR), Harvard Medical School, Belmont, MA; the Department of Psychiatry (YSL, EYK), Chung-Ang University Medical School, Seoul, South Korea; and the Department of Psychiatry (IKL), Seoul National University College of Medicine, Seoul, South Korea.

Received March 20, 2007; revised May 15, 2007; accepted May 17, 2007.

Send correspondence and reprint requests to Dr. Perry F. Renshaw, Brain Imaging Center, Mclean Hospital, 115 Mill Street, Belmont, MA 02478. e-mail:

© 2007 American Society of Addiction Medicine