During the stormy period of adolescence, teenagers undergo development to adulthood and begin to exhibit problematic behaviors or negative emotions. In adolescents, prefrontal development is still incomplete, and the amygdala, which controls fear and anger, plays a larger role in behavior; therefore, adolescents are more prone to exhibiting impulsive behaviors. In addition, adolescents’ bodies release testosterone, the male hormone, greater than are released during the juvenile period, and this hormone stimulates their aggression and anger to make them more aggressive [1]. Aggression is an intended behavior that harms or hurts others and includes the angry emotions that lead to aggressive behaviors [2].

Aggression increases during adolescence and then consistently decreases as one enters adulthood [3]. Aggression during adolescence has been reported to be associated with antisocial behaviors such as delinquency, addiction, and violence as well as with crime and school maladjustment. Families affect adolescents’ socialization and can thus play an important role in adolescents’ antisocial and criminal behaviors. Parents play the most important role in adolescents’ process of socialization [4]. Communication between adolescents and parents is known to be positively associated with adolescents’ achievement [5], self-esteem [6], and psychological health [7], and negatively associated with loneliness, depression [6], drug abuse, and delinquent behaviors [8]. Open and free parent-child communication helps prevent delinquent behaviors, whereas closed and repressive communication negatively affects the child and leads to delinquency [9].

Owing to the rapid development of information and communication technology in recent years, Internet games have become popular through high-speed Internet. Internet games have become a part of leisure activities enjoyed by children and adults, but addiction to Internet games can lead to a variety of social, physical, and psychological problems [10]. One study has shown that Internet gaming disorder (IGD) causes the same brain changes as those caused by alcohol and drug addiction [11]. The frontal lobe plays the most important role in self-recognition, behavior planning, information integration, and storing of emotions, impulses, and desire. It slowly develops between 12 and 20 years of age at the latest; thus, such brain changes affect adolescents more than they affect adults [12].

Middle school students are the most frequent users of Internet games. A survey of overdependence on the Internet has shown that adolescents occupy the highest proportion (30.6%) of the high-risk overdependence group among all age groups [13]. The risk factors of IGD that have been identified to date include stress, depression, anxiety, impulsiveness, aggression, and financial status. Of these, aggression is known as one of the causes of IGD [14-16].

Thus, this study was conducted to investigate whether or not open and free parent-child communication has a mediating effect on the risk of IGD among adolescents, since parents play a mediating role in adolescents’ delinquent and violent behaviors.

The mean aggression score measured by the AQ developed by Buss & Perry [19] was 57.34±15.00, which is somewhat lower than scores observed in previous studies [24]. The AQ defines aggression as the tendency to harm or hurt others, and aggression includes physical and verbal aggression toward others and dangerous ways of thinking and emotions. This reflects the impulsiveness or aggressive desire that adolescents experience during the process of adjusting to hormonal and environmental changes in the transitional period. The subjects in this study were first-year students in middle school. Assuming that they had not reached the peak of puberty, it is reasonable to argue that they had lower aggression scores than subjects in other studies that included the entire population of middle school students or included high school students. In a cohort study that included 5,151 adolescents aged 11-18, physical aggression reached a peak before and after the age of 15 years, and social aggression reached a peak before and after the age of 14. Adolescents tended to show low levels of aggression in early adolescence that gradually increased and then decreased with age [25].

Biological factors have been reported to affect aggression more significantly than environmental factors [26]. Brain imaging results have shown that aggression is associated with a reduced volume of gray matter in the medial prefrontal cortex and lateral frontal cortex. Reduced gray matter in the prefrontal region is associated with aggressive behaviors regardless of diagnosis of psychological disorder, and this suggests that aggression is affected by biological factors since many genetic factors come into play in the gray matter of the frontal cortex [27]. A long-term twin follow-up study showed that genetic factors play a major role in social aggression [28,29].

The DSM-5 diagnoses IGD when at least five of nine symptoms are observed. The score range for the IGUESS is 0-27 points with a cut-off point for the risk of IGD of 10 points or greater. In the IGUESS, two points are given for symptoms that occur “frequently.” Scores of 10 points or greater thus correspond to displaying five of the nine symptoms in the DSM-5 diagnostic criteria for IGD [21]. In this study, 9.0% of all subjects had the cut-off score of 10 points or greater.

A significant association was found between aggression during adolescence and the risk of IGD (r=0.32, p<0.001). This finding was consistent with a previous report that aggression affects the risk of IGD [30-32]. Thus, higher levels of aggression during adolescence indicate a higher likelihood of being included in the high-risk group for IGD.

This study investigated whether or not styles of parent-child communication can decrease the risk of IGD in the relationship between aggression and the risk of IGD and found that styles of mother-child communication had no mediating effects on the relationship between aggression and the risk of IGD, whereas styles of father-child communication did.

Analysis of the structural equation model showed that the total effect of aggression on the risk of IGD was 0.42, of which 0.29 was the direct effect and 0.13 was an indirect effect mediated by father-child communication. Standardized path coefficients of 0.1-0.3 indicate small effects, those of 0.3-0.5 medium effects, and those of 0.5 or greater large effects. Thus, father-child communication can be considered as having a medium to large effect on the association between adolescents’ aggression and the risk of IGD. Prospective randomized clinical trials are needed to investigate whether encouraging open parent-child communication contributes to reducing problematic behaviors including IGD.

Communication is a complex and dynamic interactive process. According to a theory comparing parental roles, in a traditional family the father plays an “instrumental role” as the family’s representative, whereas the mother plays an “expressive role” of satisfying emotional needs. During the process of raising children, the father plays a controlling role in his children’s behaviors, and the mother plays a nurturing role by providing affection through words, behavior, and physical contact. When playing with his/her father, a child can learn that physical violence such as kicking and biting is not socially acceptable as well as learn the proper balance between timidity and aggression [33]. Considering that parents have different impacts on their children depending on their genders, the risk of IGD may be more associated with fathers. In a British cohort follow-up study, fathers’ involvement and attitude in early adolescence had an important impact on children’s psychological health [34]. Although it is generally known that mothers have a significant impact on their children, the reason that fathers had a greater impact on the association between aggression and the risk of IGD may be that the study participants were in the first year of middle school. Further research is necessary to determine whether the results of this study are phenomena that occur during a specific period or throughout adolescence.

The effect of environmental factors on aggression varies depending on gender, with females affected relatively less by the environment [29]. To investigate the differences in the mediating effect of father-child communication on the association between aggression and the risk of IGD, a multi group structural equation model stratified by gender was analyzed. No sex differences were found, and styles of father-child communication were identified as a mediating factor for both males and females (results not provided).

This study has several limitations. First, since it is a cross-sectional study, it cannot analyze the chronological relationship between adolescents’ aggression, styles of parent-child communication, and IGD. Longitudinal studies must be conducted to understand the causal relationships between these variables.

Second, there is a possibility of misclassification since the diagnostic criteria for IGD have not been clearly established. However, the IGUESS, which classifies risk of IGD under conditions for further study in DSM-5, was used to increase the reliability and validity of such tests. Since the IGUESS is based on self-reported responses, the possibility of false positives and false negatives cannot be eliminated.

Third, the results of this study are based on subjects from four middle schools in Seoul who were selected by convenience sampling, and since the subjects were in their first year of middle school, the results cannot be generalized to the entire population of middle school students.

Previous studies evaluated the combined effects of parent-child communication styles in mediating effect on relationship between aggression and gaming addiction. However, we distinguished between mothers and fathers in parent-child communication to analyze the mediation effect using a structural equation model.

In this study, aggression during adolescence was associated with the risk of IGD. The mediating effect of father-adolescent communication observed in this study suggests that efforts for open and positive communication between fathers and adolescents are necessary.