Background and aimsData on Internet addiction (IA) and its association with personality disorder are rare. Previous studies are largely restricted to clinical samples and insufficient measurement of IA.MethodsCross-sectional analysis data are based on a German sub-sample (n = 168; 86 males; 71 meeting criteria for IA) with increased levels of excessive Internet use derived from a general population sample (n = 15,023). IA was assessed with a comprehensive standardized interview using the structure of the Composite International Diagnostic Interview and the criteria of Internet Gaming Disorder as suggested in DSM-5. Impulsivity, attention deficit hyperactivity disorder, and self-esteem were assessed with the widely used questionnaires.ResultsParticipants with IA showed higher frequencies of personality disorders (29.6%) compared to those without IA (9.3%; p < .001). In males with IA, Cluster C personality disorders were more prevalent than among non-addicted males. Compared to participants who had IA only, lower rates of remission of IA were found among participants with IA and additional cluster B personality disorder. Personality disorders were significantly associated with IA in multivariate analysis. Discussion and conclusion: Comorbidity of IA and personality disorders must be considered in prevention and treatment.

The addiction treatment system only reaches a small number of individuals suffering from Internet-related disorders. Therefore, it is important to improve case detection for preventive measures and brief interventions. Existing screening instruments are often time-consuming and rarely validated using clinical criteria. The aim of this study is to develop an optimized short screening for problematic Internet use and Internet addiction (IA). A regression analysis was conducted in random subsamples of a merged sample (N = 3,040; N = 1,209) to examine the item performance of the Compulsive Internet Use Scale (CIUS). Based on the results, a short version of the CIUS was developed and compared with the original CIUS. A fully structured diagnostic interview, covering the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for the Internet gaming disorder with a broader focus on all Internet activities, was conducted. A five-item version of the short screening performed best across the samples. Comparing the area under the curve (AUC) of the receiver operating characteristic between the Short CIUS and the original test revealed no significant difference (AUC = 0.968; 0.977). A cutoff point of 7 turned out to perform best for case detection and yielded a sensitivity of 0.95 and a specificity of 0.87, Cronbach's alpha was 0.77. The analysis showed that the performance of the Short CIUS is just as good in detecting problematical Internet use and IA as the performance of the original CIUS. The Short CIUS provides an economical and valid instrument for the assessment of problematic Internet use and IA.

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Background and aims: The diagnosis "Internet Gaming Disorder" (IGD) has been included in the fifth edition of Diagnostic and Statistical Manual of Mental Disorders. However, the nine criteria have not been sufficiently reviewed for their diagnostic value. This study focuses on a broader approach of Internet addiction (IA) including other Internet activities. It is not yet clear what the construct of IA is in terms of dimensionality and homogeneity and how the individual criteria contribute to explained variance. Methods: Three separate exploratory factor analyses and multinomial logistic regression analyses were carried out based on information collected from a general populationbased sample (n = 196), a sample of people recruited at job centers (n = 138), and a student sample (n = 188). Results: Both of the adult samples show a distinct single-factor solution. The analysis of the student sample suggests a two-factor solution. Only one item (criterion 8: escape from a negative mood) can be assigned to the second factor. Altogether, high endorsement rates of the eighth criterion in all three samples indicate low discriminatory power. Discussion and conclusions: Overall, the analysis shows that the construct of IA is represented one dimensionally by the diagnostic criteria of the IGD. However, the student sample indicates evidence of age-specific performance of the criteria. The criterion "Escape from a negative mood" might be insufficient in discriminating between problematic and non-problematic Internet use. The findings deserve further examination, in particular with respect to the performance of the criteria in different age groups as well as in non-preselected samples.

Background and aims An increasing number of people experience negative consequences from the excessive use of different Internet applications or sites (e.g., Instagram, League of Legends, YouTube). These consequences have been referred to as specific Internet Use Disorders (IUDs). The present study aims to examine the Fear of Missing Out (FoMO) on rewarding experiences with respect to specific Internet activities. FoMO has been found to mediate the link between psychopathology and symptoms of Internet Communication Disorder (ICD). However, the role of FoMO in other IUDs is controversial. Methods The current study (N = 7,990) consecutively screened in vocational schools) analyzed the associations between online-specific state-FoMO, general trait-FoMO, mental health, and IUD symptoms in a structural equation model. After testing the model for the entire sample of Internet users, it was analyzed separately for the two main user groups: Social Networking Site (SNS) users and gamers. Results The proposed model explained 42.0% of the variance in IUD symptoms in the total sample, 46.8% for SNS users, and 32.8% for gamers. Results suggest that impaired mental health and high trait-FoMO predict IUD symptoms. For both SNS users and gamers, trait-FoMO mediated the link between low mental health and IUD, whereas state-FoMO mediated the link between trait-FoMO and IUD in both user groups. Discussion Our results partly support the theoretical model of specific IUDs, highlighting trait-FoMO as a predisposing fear of disconnection related to general mental health. Online-specific FoMO appears to contribute to problematic Internet use mainly because of its link to the general fear of disconnection. Moreover, the described mechanism seems to be comparable for both females and males. Conclusions FoMO is a multidimensional construct underlying IUD symptoms related to the use of socially gratifying, but distinct Internet applications. FoMO and psychopathology should be targeted together in prevention and treatment plans of IUDs.