Internet addiction: Associated with lower health-related quality of life among college students in Taiwan, and in what aspects?

Accepted Manuscript Internet addiction: Associated with lower health-related quality of life among college students in Taiwan, and in what aspects?

Kae-Chyang Chern, Jiun-Hau Huang PII:

S0747-5632(18)30116-X

DOI:

10.1016/j.chb.2018.03.011

Reference:

CHB 5415

To appear in:

Computers in Human Behavior

Received Date:

15 October 2017

Revised Date:

25 February 2018

Accepted Date:

07 March 2018

Please cite this article as: Kae-Chyang Chern, Jiun-Hau Huang, Internet addiction: Associated with lower health-related quality of life among college students in Taiwan, and in what aspects?, Computers in Human Behavior (2018), doi: 10.1016/j.chb.2018.03.011

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ACCEPTED MANUSCRIPT Title Internet addiction: Associated with lower health-related quality of life among college students in Taiwan, and in what aspects?

Authors and affiliations Kae-Chyang Chern1, Jiun-Hau Huang1,2,3,*,§ 1Institute

of Health Policy and Management, College of Public Health, National Taiwan University,

Taipei, Taiwan 2Institute

of Health Behaviors and Community Sciences, College of Public Health, National Taiwan

University, Taipei, Taiwan 3Department

of Public Health, College of Public Health, National Taiwan University, Taipei,

Taiwan

*Corresponding author. Jiun-Hau Huang, SM, ScD, Institute of Health Behaviors and Community Sciences, College of Public Health, National Taiwan University, 17 Xu-Zhou Road, Taipei 10055, Taiwan, Tel/Fax: +886-2-3366-8054, E-mail: [email protected] §Contributed

equally to this work as first author.

ACCEPTED MANUSCRIPT Title Internet addiction: Associated with lower health-related quality of life among college students in Taiwan, and in what aspects?

Abstract Internet use has been integrated into college students’ daily lives for learning and social purposes. However, little is known about whether those with Internet addiction (IA) had lower health-related quality of life (HRQOL) in physical, psychological, social, and environment domains. Survey data from 1,452 college students in Taiwan were collected using proportional stratified sampling (response rate=84.2%). IA, including 5 IA manifestations, and HRQOL were assessed by Chen Internet Addiction Scale and World Health Organization Quality of Life (WHOQOL-BREF) Taiwan version, respectively. College students with IA reported significantly lower HRQOL in all 4 domains (B=-.130, -.147, -.103, and -.085, respectively). Furthermore, 3 IA manifestations, namely compulsivity (B=-.096), interpersonal and health problems (B=-.100), and time management problems (B=-.083), were significantly associated with lower physical HRQOL; compulsivity was also associated with decreased psychological (B=-.166) and environment (B=-.088) HRQOL; lastly, interpersonal and health problems owing to Internet use was associated with lower social HRQOL (B=-.163). These findings warrant further research into the mechanisms through which IA relates to HRQOL in youths. Multi-faceted tailored interventions are needed to target early IA manifestations, thereby preventing IA and associated health consequences.

Keywords Internet addiction; Internet addiction manifestations; Health-related quality of life (HRQOL); WHOQOL-BREF; College students; Taiwan

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ACCEPTED MANUSCRIPT 1. Introduction Internet use has been interwoven into the fabric of our daily lives for various purposes. However, excessive Internet use can also be pathological and addictive, commonly referred to as “Internet addiction (IA)” [1]. Further, it has been proposed that, like patients with substance use disorder, excessive Internet users are affected by core symptoms of addictions, such as salience, tolerance, and interpersonal conflict. [2]. According to an editorial calling for more attention to IA and recommending its inclusion in the DSM-5, IA has been regarded as one of the most serious public health issues in South Korea, and China’s government has even enacted laws to regulate adolescent Internet use behavior [3]. Notably, college students have been documented to be particularly vulnerable to IA, given their psychological and developmental characteristics of late adolescence and ready access to the Internet [4]. A national survey in Taiwan reported that more than 99.5% of people aged 15–24 were Internet users [5]. Prior research among adolescents and youths, including college students, has also found that their prevalence of IA ranged from 5.9% to 26.8% [6-12]. With rapid advances in Internet technologies and high Internet penetration rates in Taiwan, there is reason to be concerned that IA may worsen in the college student population owing to their increasing dependence on the Internet for learning and social purposes. Numerous studies have demonstrated harmful health effects of IA across different aspects of health. First, physical health could be affected because IA was often associated with a number of unhealthy lifestyles, including poor diets,[8] physical inactivity [13], drinking behavior [13, 14], and late-night Internet use [15, 16]. Further, as an addiction itself, IA could have detrimental effects

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ACCEPTED MANUSCRIPT on one’s psychological health, especially in the presence of its commonly co-occurring psychiatric disorders, such as attention-deficit/hyperactivity disorder (ADHD) and depression [17, 18], which may further exacerbate psychological health [19, 20]. In addition, IA has also been found to be related to lower life satisfaction with family, friends, school, and living environment [13, 21, 22], suggesting that IA could have adverse effects on the social and environmental aspects of health. However, despite the above findings showing various harmful effects of IA, little empirical research has systematically examined the relationships between IA and health from a holistic perspective. According to the World Health Organization (WHO), health is defined as a complete state of physical, mental, and social well-being [23]. In consistence with this definition and holistic approach, measures of health-related quality of life (HRQOL) have been developed and increasingly used in health research [24]. Moreover, the concept of HRQOL has also been recommended to be incorporated into addiction research, because addictions, much like a chronic condition, have features that can affect various aspects of people’s quality of life [25]. In view of the integral role of Internet use in the daily lives of college students, it is instrumental to employ HRQOL to comprehensively evaluate the relationships between IA and health using the WHO’s framework for assessment of health. To our knowledge, however, there is a scarcity of literature investigating the relationships between IA and HRQOL in the college student population. Therefore, the present study aimed to bridge this gap by systematically examining the associations between IA and HRQOL with standardized measures. On the basis of the literature reviewed above, this study hypothesized that

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ACCEPTED MANUSCRIPT IA would be negatively related to all domains of HRQOL. Further, this study also hypothesized that various IA manifestations would be differentially related to different domains of HRQOL. These findings could provide insights into possible mechanisms through which IA may negatively relate to HRQOL, and inform future research and prevention programs to mitigate the effects of IA among college students.

2. Methods 2.1 Participants Undergraduate students aged 18 years or older were recruited from 2 of the largest comprehensive universities in Taiwan, one being public and the other private. To ensure the representativeness of the academic diversity within the universities, proportional stratified cluster sampling was employed to draw a random sample, using discipline-based colleges (e.g., liberal arts, social sciences, engineering, biomedical and life sciences) as strata and student classifications within each department as clusters. All students in the sampled clusters were invited to participate in this study, and 1,452 students voluntarily completed the survey (response rate=84.2%). After 13 responses were removed because the participants accidentally skipped 1 or more pages of the questionnaire, a total of 1,439 valid surveys were included in the final analyses. Also, the clustering effect was assessed and found negligible across sampled clusters, with the intracluster correlation coefficients [ICCs] for the HRQOL measures all being below .05; more methodological details have been reported elsewhere [26].

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ACCEPTED MANUSCRIPT 2.2 Measures 2.2.1 Internet addiction: Chen Internet Addiction Scale Internet addiction was measured by the 26-item Chen Internet Addiction Scale (CIAS), a standardized, validated, and widely used instrument to assess IA in prior research [7, 9, 27]. This scale consists of 5 IA manifestations, including: Compulsivity (5 items), Withdrawal (5 items), Tolerance (4 items), Interpersonal and Health Problems (7 items), and Time Management Problems (5 items). Each item was rated on a 4-point Likert-type scale from “not at all fit” to “very fit” (scored from 1 to 4) [28], resulting in a total score of 26-104. In prior research, the cut-off score of ≥64 has exhibited satisfactory psychometric properties for screening college students with IA [29], and hence was also used to classify IA in this study among college students. In addition, in order to further illuminate the ways in which IA might affect college students’ HRQOL, we also examined the relationships between the 5 IA manifestation scores and HRQOL. 2.2.2 Health-related quality of life: WHOQOL-BREF In this study, health-related quality of life (HRQOL) was measured by the World Health Organization Quality of Life assessment short version (WHOQOL-BREF), one of the most widely used HRQOL instruments that could be applied in diverse cultural settings for international comparisons [30, 31]. The WHOQOL-BREF consists of 26 items and encompasses 4 domains that are essential for the assessment of quality of life—1) Physical (7 items; e.g., “Do you have enough energy for your daily life?”); 2) Psychological (6 items; e.g., “Do you often have negative feelings?”); 3) Social (4 items; e.g., “Are you satisfied with your personal relationships?”); and 4)

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ACCEPTED MANUSCRIPT Environment (9 items; e.g., “Do you have enough money for whatever you need?”)—with internal consistency Cronbach’s α between 0.70-0.77 and test-retest reliability correlation between 0.760.80 [30]. As per the WHOQOL-BREF manual, the mean score of items within each domain was multiplied by 4 to create the domain score, ranging from 4 to 20, with a higher score indicating higher HRQOL [24]. 2.2.3 Background variables ADHD and depression were evaluated in this study, as they have both been reported to be comorbid with IA in prior research [17]. ADHD was measured by the short version of Adult ADHD Self-Report Scale (ASRS), and a dichotomous variable was created as per its guidelines [32]. The severity of depression was assessed by the Patient Health Questionnaire (PHQ-9), and a total score greater than 5 and 10 indicates “mild” and “moderate to severe” depression, respectively, in this study [33, 34]. Moreover, college students were asked whether they had been diagnosed with any physical or mental disorders (excluding the aforementioned ADHD and depression) as they might affect their HRQOL. Similarly, given that smoking, unprotected sex, and heavy episodic drinking commonly occur in college students [35] and have also been found to affect their HRQOL [36], participants were asked whether they had participated in these risk behaviors in the past year. Lastly, a number of important background characteristics of the college student population were also adjusted for in the analyses, such as gender, year in university, region of origin, in a stable relationship, type of university, grade point average, sexual orientation, religion status, and monthly disposable income.

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ACCEPTED MANUSCRIPT 2.3 Procedure In sampled classes, researchers explained the survey procedure and stressed that each student’s responses were anonymous and confidential. Voluntary completion of the survey constituted the informed consent to participate. To enhance the response rate, each participant was offered a small gift and a chance to win a cash prize worth around US$3.50. All survey data were gathered in March 2013. The study protocol was reviewed and approved by the Research Ethics Committee of [omitted for blind review as instructed]. Data analyses were performed using SPSS 20.0. Descriptive analyses were conducted for all variables. Then, the bivariate associations of IA status and 5 IA manifestation scores with 4 HRQOL domain scores were evaluated by t-test and Pearson’s correlation, respectively. Finally, 2 sets of multivariate linear regression models were estimated to evaluate the associations: (1) between IA (yes/no) and 4 HRQOL domain scores; and (2) between 5 IA manifestation scores and 4 HRQOL domain scores. Both sets of multivariate models controlled for the aforementioned background variables.

3. Results Data from 1,439 college students were included in the analyses. The mean age of participants was 20.51 (SD=1.82), more than half (58.4%) were females, slightly more students were in their junior year (30.2%), nearly 8 in 10 students (78.3%) were from the local area, 38.0% were in a stable relationship, and approximately half (51.5%) had a GPA in the top 40%. According to the

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ACCEPTED MANUSCRIPT ASRS and PHQ-9 scales, 12.4%, 41.7%, and 16.6% were classified as having ADHD, mild, and moderate to severe depression, respectively. Lastly, 22.2% and 1.0% reported having been diagnosed with any physical and mental disorders, respectively. As shown in Table 1, 33.9% of the sampled college students were classified as having IA according to the CIAS, and these students reported significantly lower HRQOL scores in all 4 domains. With regard to 5 IA manifestation scores, all of them had significantly negative correlations with all 4 HRQOL domain scores. Table 1

Internet addiction (IA), 5 IA manifestation scores, and their associations with 4 HRQOL

domain scores among sampled college students (N = 1,439) Variable

n

%

Internet Addiction

Physical M p (SD)

Psychological M p (SD)

< .001

No

951

66.1

Yes

488

33.9

Social M (SD)

< .001

p

Environment M p (SD)

< .001

< .001

12.82 (1.64) 11.85 (1.88)

13.65 (2.29) 12.19 (2.30)

13.92 (2.07) 12.82 (2.32)

14.32 (1.88) 13.57 (2.03)

r

r

r

r

IA M (SD) Manifestations Compulsivity 10.79 (2.85)

-.278

< .001

-.330

< .001

-.261

< .001

-.196

< .001

Withdrawal

11.92 (2.84)

-.207

< .001

-.245

< .001

-.210

< .001

-.145

< .001

Tolerance Interpersonal and Health Time Management

9.69

(2.24)

-.220

< .001

-.266

< .001

-.184

< .001

-.135

< .001

15.23 (3.72)

-.317

< .001

-.324

< .001

-.306

< .001

-.211

< .001

10.96 (3.20)

-.275

< .001

-.256

< .001

-.234

< .001

-.174

< .001

aEach

of the 4 HRQOL domain scores ranges from 4 to 20. score of each IA manifestation is as follows: compulsivity (5-20); withdrawal (5-20); tolerance (4-16); interpersonal and health problems (7-28); time management problems (5-20). cp derived from t-test or Pearson’s correlation test, as appropriate. bThe

In Tables 2 and 3, multivariate linear regression analyses examined the associations of IA (yes/no) and 5 IA manifestation scores, respectively, with 4 HRQOL domain scores. We found that college students with IA (Table 2) reported significantly lower HRQOL in physical, psychological,

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ACCEPTED MANUSCRIPT social, and environment domains (B = -.130, -.147, -.103, and -.085, respectively), after controlling for the background variables. Similarly, 3 of 5 IA manifestations were also found significantly associated with lower HRQOL in different domains (Table 3). Specifically, compulsivity, interpersonal and health problems, and time management problems were significantly associated with decreased physical HRQOL (B= -.096, -.100, and -.083, respectively); compulsivity was also negatively associated with HRQOL in the psychological (B = -.166) and environment (B = -.088) domains; lastly, interpersonal and health problems were linked to lower social HRQOL (B = -.163). Finally, since the relationships between background variables and HRQOL were similar in the multivariate regression models shown in Tables 2 and 3, we only reported below significant results in Table 2. Males had significantly higher physical (B = .065), but lower social (B = -.136) HRQOL than females. Compared with freshmen, juniors and seniors had significantly lower HRQOL in the physical (B = -.097 and -.080, respectively) and social (B = -.102 and B = -.146, respectively) domains; seniors also reported significantly lower psychological HRQOL (B = -.090). Students from out of town had significantly lower HRQOL in the environment domain (B = -.079), and those in a stable relationship reported significantly higher psychological (B = .097) and social (B = .147) HRQOL. Students with ADHD reported significantly lower physical (B = -.062) and social (B = -.061) HRQOL. Lastly, significantly lower HRQOL in all 4 domains were found among students with “mild” (B = -.282, -.299, -.238, and -.225, respectively) and “moderate to severe” (B = -.379, -.441, -.301, and -.293, respectively) depression.

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Table 2

Multivariate linear regression models: associations between Internet addiction and 4 HRQOL domain scores Variable Background Variables Gender Female (ref) Male Year in University 1st (ref) 2nd 3rd 4th Region of Origin Local (ref) Out of town In a Stable Relationship No (ref) Yes ADHD No (ref) Yes Severity of Depression None (ref) Mild Moderate to severe Internet Addiction No (ref) Yes 2 R Adjusted R2 F

Physical B

ΔR2

Psychological B

.211*** -.065*

ΔR2

.271*** -.024

--.003 -.097** -.080*

-.000 -.037 -.090**

--.026

-.014

-.021

Social B

-.097***

ΔR2

Environment B

.210***

.152***

--.136***

--.004

--.040 -.102** -.146***

--.009 -.042 -.064

--.012

--.079**

-.147***

--.007

--.062*

--.044

--.061*

--.008

--.282*** -.379***

--.299*** -.441***

--.238*** -.301***

--.225*** -.293***

.015*** --.130***

.018*** --.147***

.009*** --.103***

.225 .210 14.899***

.290 .276 20.879***

ΔR2

.006** --.085**

.219 .204 14.370***

.158 .141 9.595***

Abbreviations: HRQOL, health-related quality of life; ADHD, Attention-deficit/hyperactivity disorder; B, standardized regression coefficient; * p < .05; ** p < .01; *** p < .001. All models controlled for type of university (public/private), grade point average, sexual orientation, religion status, monthly disposable income, diagnosed physical disorder, diagnosed mental disorder (excluding depression and ADHD), and past-year heavy episodic drinking, smoking, and unprotected sex.

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Table 3

Multivariate linear regression models: associations between 5 IA manifestation scores and 4 HRQOL domain scores

Variable Background Variables Gender Female (ref) Male Year in University 1st (ref) 2nd 3rd 4th Region of Origin Local (ref) Out of town In a Stable Relationship No (ref) Yes ADHD No (ref) Yes Severity of Depression None (ref) Mild Moderate to severe IA Manifestations Compulsivity Withdrawal Tolerance Interpersonal and Health Time Management R2 Adjusted R2 F

Physical B

ΔR2

Psychological B

ΔR2

.211*** -.069*

.271*** -.022

-.009 -.083* -.064*

-.009 -.028 -.081**

--.022

-.015

-.018

Social B

-.093***

ΔR2

Environment B

.210***

.152***

--.136***

--.004

--.027 -.087** -.135***

--.001 -.033 -.055

--.010

--.077**

-.150***

--.001

--.050

--.037

--.049

--.001

--.255*** -.349***

--.282*** -.421***

--.213*** -.273***

--.208*** -.274***

-.096* -.016 .022 -.100** -.083*

.025*** .000 .000 .008*** .003* .248 .231 14.528***

-.166*** .005 -.016 -.042 -.011

.036*** .000 .000 .001 .000 .309 .293 19.654***

-.074 -.027 .060 -.163*** .021

ΔR2

.018*** .000 .000 .011*** .000 .240 .223 13.898***

-.088* .016 .016 -.075 -.010

.012*** .000 .000 .003* .000 .166 .147 8.786***

Abbreviations: HRQOL, health-related quality of life; ADHD, Attention-deficit/hyperactivity disorder; B, standardized regression coefficient; * p < .05; ** p < .01; *** p < .001. All models controlled for type of university (public/private), grade point average, sexual orientation, religion status, monthly disposable income, diagnosed physical disorder, diagnosed mental disorder (excluding depression and ADHD), and past-year heavy episodic drinking, smoking, and unprotected sex.

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ACCEPTED MANUSCRIPT 4. Discussion The current study sought to bridge the gap in the existing literature on the relationships between IA and the 4 domains of HRQOL in college students. It is worth noting that, even after controlling for a comprehensive set of background variables that may affect students’ HRQOL, this study still found significant independent associations between IA and HRQOL. As hypothesized, IA was negatively related to all 4 domains of HRQOL. In addition, our findings also provided empirical support for our other hypothesis that various IA manifestations were significantly and differentially related to lower HRQOL in different domains. 4.1 IA associated with lower HRQOL in all 4 domains This study found that around one in three college students was classified as having IA according to their self-reported CIAS score. Even more worrisome is that these college students with IA reported significantly lower HRQOL in all 4 domains, suggesting that IA permeated through all aspects of HRQOL in their lives. As the Internet continues to fulfill the needs of information, entertainment, and social interactions, Internet use becomes an indispensable part of our daily lives, especially for college students, whose learning and social networking involve Internet use. Clearly, a delicate balance needs to be maintained between Internet use and misuse in this population. Therefore, student counseling professionals should pay more attention to this issue and provide timely assistance to those exhibiting early manifestations of IA. Notably, while this study systematically examined the relationship between IA and HRQOL, caution needs to be used when interpreting the causality and temporality of the results because of the cross-sectional design

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ACCEPTED MANUSCRIPT of this study. More empirical research is also warranted to further explore the relationships between IA and lower HRQOL as found in this study and to help develop effective IA prevention programs. 4.2 3 IA manifestations associated with lower HRQOL in the physical and social domains This study found that 3 specific IA manifestations (i.e., compulsivity, interpersonal and health problems, and time management problems) were associated with lower physical HRQOL among college students. A possible explanation is that students with higher compulsivity may have impaired control over Internet use, thereby developing the other two types of IA problems manifested through unhealthy lifestyles, such as poor diets and sleep deprivation, which may lead to lower physical HRQOL. This line of argument is corroborated by an auxiliary analysis, showing significant positive correlations among these 3 IA manifestations. It is also noteworthy that a longitudinal study in Hong Kong found that among all IA behaviors, problems related to time management, such as staying on-line longer than originally intended, had been consistently reported to be the most common issue among the participants during the six-year study period (42.4% to 47.7%) [11]. Such findings, combined with our empirical results, underscore the significance of the time management problem manifestation as we develop IA intervention programs to prevent worsened physical HRQOL associated with IA. In addition, students showing interpersonal and health problems owing to Internet use also reported lower social HRQOL. Since this IA manifestation encompasses interpersonal problems, it is reasonable that it is linked to lower social HRQOL. Understandably, college students immersed in the cyberspace may become increasingly isolated from face-to-face interactions and social

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ACCEPTED MANUSCRIPT activities in real life, thus gradually lowering their social HRQOL. Conversely, given the crosssectional nature of this study, it is also likely that students with lower social HRQOL may lack interpersonal skills to begin with, and hence may find solace in the cyberspace to escape from reality or to cope with their loneliness, which may further exacerbate their IA and existing interpersonal problems, leading to a vicious circle. Therefore, longitudinal research is needed to elucidate the possible mechanisms of the relationships as discussed above. More intervention initiatives are also merited to help students enhance their interpersonal and life skills to mitigate these IA problems and to prevent declined physical and social HRQOL associated with IA. 4.3 IA-related compulsivity associated with lower HRQOL in the psychological and environment domains College students with elevated compulsivity regarding Internet use also reported lower psychological and environment HRQOL. Similar to other compulsive disorders, compulsivity concerning Internet use may cause feelings of anxiety, which may harm college students’ psychological HRQOL. Besides, college students with higher compulsivity may spend larger expenditures on Internet-related activities such as online games and cybersex chats. Consequently, they may feel financially insufficient (i.e., a facet of environment HRQOL), which could be linked to lower environment HRQOL. Conversely, those with poor psychological HRQOL may innately have compulsive personality traits and hence are more prone to develop IA and related compulsivity manifestations, thereby linking lower psychological HRQOL to compulsivity. However, it is worth noting that previous longitudinal studies among adolescents [19] and adults [20] have both

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ACCEPTED MANUSCRIPT demonstrated that compulsive Internet use predicted poor mental health and well-being (i.e., depression, loneliness, and stress), respectively, whereas poor mental health did not predict the development of compulsive Internet use. These findings appear to support the temporality and directionality of IA-related compulsivity being an upstream cause and leading to poor psychological HRQOL. Additional research can help shed more light on their relationship. Regardless of the causality, the negative associations found in this study between IA-related compulsivity and HRQOL in various domains highlight the need for intervention programs to sensitize college students to their potential compulsive Internet use, and to provide guidance to facilitate better self-regulation. In addition, since cognitive behavioral therapy (CBT) has been shown to be an effective treatment for compulsive disorders [37], mental health professionals may consider offering CBT to college students exhibiting IA-related compulsivity to help ameliorate its impact and associated declines in psychological and environment HRQOL. 4.4 Potential synergistic harmful effects of IA and depression on HRQOL In an ancillary analysis (data not shown), chi-square comparisons found that IA was significantly associated with severity of depression, corroborating the comorbidity between IA and depression reported in prior research [6, 17]. An additional Cochran-Armitage trend test also found that as the severity of depression increased, so did the risk of IA (p < .001). More worrisome is that, as demonstrated in this study, depression was strongly linked to lower HRQOL, but above and beyond depression, IA was also associated with decreased HRQOL in all 4 domains. Besides, IA also independently explained a significant proportion of the HRQOL variance in all 4 domains,

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ACCEPTED MANUSCRIPT hence warranting the inclusion of IA as a risk factor in future investigations of college students’ HRQOL. Notably, depression has been rated as the top leading cause of burden of disease in middle and high income countries, where the Internet may also be widely and readily accessible [38], thus elevating the risk of IA as well. Therefore, while further research is needed to clarify the intertwined interrelationships among IA, depression, and HRQOL, in light of the present findings, multi-component prevention initiatives that tackle IA and depression simultaneously are recommended to ameliorate the potential synergistic harmful effects of IA and depression on HRQOL. 4.5 Other background variables associated with college students’ HRQOL In this study, we also found several sociodemographic variables to be associated with college students’ HRQOL. For example, male students reported better physical but poorer social HRQOL than their female counterparts, which could be attributed to biological sex differences, varying lifestyles (e.g., physical activity), and dissimilar patterns of social interactions [39]. Moreover, given the commonly found gender differences in addictive behaviors, including IA, in the existing literature [11, 40], gender-sensitive approaches have been recommended for intervention programs designed to curb addiction. Further, college students in their junior and senior years generally reported lower physical, psychological, and social HRQOL, possibly resulting from their increased academic and post-graduation career pressures [41] and ensuing unhealthier lifestyles [42]. Also, students from out of town had lower HRQOL in the environment domain, perhaps owing to their relative unfamiliarity with the environment and having fewer local resources. In addition, students

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ACCEPTED MANUSCRIPT in a stable relationship reported higher HRQOL in both psychological and social domains, as they might receive more support from their partners. Conversely, it is also possible that those with better psychological and social HRQOL might have a more positive mindset, higher self-esteem, and better interpersonal skills and social networks, and thus might be more likely to be in a stable relationship. These findings provide empirical evidence for HRQOL disparities across sociodemographic groups and can inform the development of tailored prevention programs and allocation of resources. Lastly, ADHD was associated with lower physical and social HRQOL in the multivariate models controlling for IA status; yet, when instead controlling for the 5 IA manifestations in the parallel set of models, the statistical significance of ADHD disappeared. In the former set of models, the findings are consistent with previous studies among college students in which ADHD was found to be associated with poorer health-related physical fitness [43] and higher social impairment [44]. However, in the latter set of models, ADHD became non-significant; instead, 3 of the 5 IA manifestations (i.e., compulsivity, interpersonal and health problems, and time management problems) were significantly associated with lower physical HRQOL, and interpersonal and health problems were significantly associated with lower social HRQOL, suggesting that these significant IA manifestations might be co-occurring with ADHD but could more specifically and better capture its relationships with physical and social HRQOL. Notably, the 5 IA manifestations jointly explained more variance of HRQOL than IA status in the physical (.036 versus .015) and social (.029 versus .009) domains, which might also account for the greater

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ACCEPTED MANUSCRIPT explanatory power of the 5 IA manifestations and resultant significance in the models, compared with ADHD. The models with the 5 IA manifestations not only exhibit the above advantages over the models with IA status, but also provide insights into the ways in which ADHD might relate to lower HRQOL through specific comorbid IA manifestations as found in this study. 4.6 Limitations and future directions Some limitations to this study should be noted. First, since the current study relied on selfreport, there are common issues that self-administered surveys would encounter, such as potential reporting bias. However, this survey was anonymous and employed empirically validated measures for our main study variables, and a pilot test was also conducted to ensure clarity and appropriateness of survey items. Hence, concerns about reporting bias are likely to be minimal and internal validity is enhanced. Second, although this study employed proportional stratified cluster sampling method to draw a relatively large sample of college students from two of the largest comprehensive universities in Taiwan, including one public and one private university, as well as a wide range of academic disciplines and student backgrounds that reflect the general college student population, the representativeness issue should still be noted. After all, the sample was based on two universities only, and therefore, caution needs to be exercised when attempting to generalize the present findings to the entire college student population. Future research should consider drawing a larger national sample and examine if our study results could be replicated. Also, similar studies can be conducted in other countries for cross-national comparisons. Lastly, the cross-sectional design constrains our ability to make causal inferences. Therefore, longitudinal research is needed in the

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ACCEPTED MANUSCRIPT future to confirm their temporal relationships, to further illuminate the underlying mechanisms between IA and HRQOL, and to help monitor the trend of IA in this population. 4.7 Conclusions This study aimed to bridge the gap in the current literature on the relationships between IA and HRQOL among college students. The present study demonstrated that college students with IA had significantly lower HRQOL in physical, psychological, social, and environment domains. Further, specific IA manifestations, such as compulsivity, interpersonal and health problems, and time management problems, were linked to lower HRQOL in different domains. Together, these findings illustrate that IA should be regarded as a major health concern and incorporated into health education and intervention initiatives for college students. Especially considering that Internet use has permeated into our daily lives, more research is warranted to elucidate the mechanisms through which IA, an emerging disorder, affects our HRQOL, and also to facilitate the development of optimally effective programs to prevent the negative effects of Internet use on overall HRQOL.

Compliance with Ethical Standards Ethical Approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed Consent: Informed consent was obtained from all individual participants included in the study.

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ACCEPTED MANUSCRIPT Acknowledgments This work was supported in part by the Ministry of Science and Technology, Taiwan (formerly, National Science Council) [grant numbers MOST 105-2410-H-002-143-MY2, MOST 103-2410-H002-225-MY2, NSC 102-2410-H-002-220-, and NSC 100-2410-H-002-174-MY2], awarded to Dr. Jiun-Hau Huang.

ACCEPTED MANUSCRIPT Highlights 

Internet addiction was negatively related to every aspect of health-related quality of life in college students.

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Various Internet addiction manifestations were differentially related to different domains of quality of life.

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Internet addiction should be tackled together with depression for synergistic harmful effects.