Depression like characteristics of 5HTTLPR polymorphism and temperament in excessive internet users.
BACKGROUND
Excessive internet use (EIU) has been reported to be comorbid with depression and the manifestation of its symptoms. This study examines the characteristics of excessive internet users that are similar to those of patients with depressive disorders in terms of serotonin transporter gene expression and harm avoidance.


METHODS
91 male adolescents with EIU and 75 healthy comparison subjects were recruited. Between group comparisons were made on genetic polymorphisms of the serotonin transport gene and with respect to novelty seeking and harm avoidance (HA) of Cloninger's Temperament Character Inventory.


RESULTS
The homozygous short allelic variant of the serotonin transporter gene (SS-5HTTLPR) is more frequent in the EIU group (chi(2)=4.38, df=1, p<0.05). The HA and Beck Depression Inventory (BDI) scores were significantly higher in the EIU group than in the healthy comparison group (t=7.03, df=164, p<0.01; t=2.12, df=164, p=0.04). EIU subjects expressing SS-5HTTLPR also showed higher HA (HA1, HA2, HA4, and total HA) and Young's internet addiction scale scores than EIU subjects expressing the other serotonin transporter gene allele variants (t=2.47, df=89, p=0.01; t=2.33, df=89, p=0.02; t=2.17, df=89, p=0.03; t=2.25, df=89, p=0.03; t=2.93, df=89, p<0.01 respectively).


CONCLUSIONS
The EIU group had higher SS-5HTTLPR frequencies, harm avoidance, and BDI scores. SS-5HTTLPR expression was closely related to harm avoidance in EIU. The results of this study suggest that EIU subjects may have genetic and personality traits similar to depressed patients.
Department of Psychiatry, Chung-Ang University Medical School, Seoul, South Korea.
Young Sik
YS
Lee
Doug Hyun
DH
Han
Kevin C
KC
Yang
Melissa A
MA
Daniels
Chul
C
Na
Baik Seok
BS
Kee
Perry F
PF
Renshaw
D000293:Adolescent; D000483:Alleles; D003863:Depression / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D040261:Harm Reduction; D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D013694:Temperament
C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins