“Internet addiction” was first described in the dial-up era (Young KS. Psychol Rep 1996;79:899-902), with the prevalence steadily increasing with more widespread internet access. Five years ago, a meta-analysis reported a global prevalence of 6.0% (Cheng et al. Cyberpsychol Behav Soc Netw 2014;17:755-760). More recent estimates have found a prevalence of 17.7% among adolescents in rural Japan (Kojima et al. Psychiatry Clin Neurosci 2019;73:20-26), and 38.2% among university students in Japan (Kitazawa et al. Psychiatry Clin Neurosci 2018;72:531-539). The range in prevalence is largely due to a lack of consensus on diagnostic criteria, which in itself is a reflection of a more fundamental controversy: is Internet overuse an “addiction” or only problematic?

In a review of the topic, Aboujaoude noted that the initial conception of internet overuse was akin to a physical addiction, modelled on DSM-IV criteria for substance dependence (Aboujaoude E. World Psychiatry 2010;9:85-90). Others viewed the problem as a behavioural issue more in keeping with DSM-IV criteria for impulse control disorder. As such, some preferred the term “problematic Internet use” or “pathological Internet use” (PIU) rather than Internet addiction. PIU was then defined as a maladaptive preoccupation with Internet use experienced as irresistible use for periods of time longer than intended; and associated with significant distress or impairment (Shaw et al. CNS Drugs 2008;22:353-365). In DSM-V, behavioural addiction (non-substance-related addictive disorder) was included as a diagnostic category, with gambling disorder as the only condition listed; Internet gaming disorder was considered but was ultimately relegated to the back of the book as something requiring further study (reviewed in Durkee et al. Int J Environ Res Public Health 2016;13:294). PIU was not included.

Over the past five years, there has been an increasing number of studies investigating PIU, an effort that has been hampered by a lack of a standardized assessment, and tools that reflect PIU’s roots in addiction. Common tools include Young’s Diagnostic Questionnaire for Internet addiction (8 questions) (Young 1998) and Internet Addiction Test (20 questions) (Young KS. New York: Wiley, 1998); Ko’s Diagnostic Criteria for Internet Addition for adolescents (3 criteria) (Ko et al. J Nerv Ment Dis 2005;193:728-733); and the Chen Internet Addiction Scale (26 items) (Chen et al. Chin J Psychol 2003;45:279-294).

A further problem is that systematic reviews generally do not distinguish among different online activities, although it is reasonable to assume that distinctions should be made among the many conditions that have been described, such as Internet gaming disorder (Petry et al. Addiction 2014;109:1399-1406); Facebook addiction disorder (Andreassen et al. Psychol Rep 2012;110:501-501), itself a subset of Social Media Addiction (Sriwilai & Charoensukmongkol. Stress Health 2016;32:427-434); Internet Pornography Use Disorder (Pekal et al. J Behav Addict 2018;7:574-583); Smartphone addiction (Bianchi & Phillips. CyberPsychol Behav 2005;8:39-51); and others.

Perhaps more clinically relevant is PIU’s relationship to other psychopathology. A systematic review of 20 studies found PIU was significantly correlated with attention deficit-hyperactivity disorder, depression, anxiety, obsessive-compulsive symptoms, and hostility/aggression (Carli et al. Psychopathology 2013;46:1-13). The plethora of associations likely obscures the distinction between Internet usage as a means of coping with pre-existing psychiatric symptoms and psychosocial dysfunction versus being a cause of psychiatric symptoms. With respect to coping, one study reported that phobic anxiety, wishful thinking and concerns about body weight predicted PIU in males; depression, keeping to oneself and tension reduction predicted PIU in females (Hetzel-Riggin & Pritchard. Cyberpsychol Behav Soc Netw 2011;14:519-525). Other studies have suggested individuals with anxious attachment styles may overuse social media as a means of enhancing psychological well-being (Worsley et al. Cyberpsychol Behav Soc Netw 2018;21:563-568).

What has been more clearly determined are the consequences of prolonged Internet use, including negative impacts on relationships, social interactions, extracurricular activities, physical activity, eating habits and sleeping (Durkee 2016).

However, the social context of Internet use needs to be considered. In the systematic review cited above (Carli 2013), most of the PIU studies were conducted in Asia; the same applies to many of the studies of smartphone addiction (Kwon et al. PLoS One 2013;8:e56936). This suggests that the sociocultural context of smartphone and other Internet addictions, and normative behaviours within social and age groups, should be factored in before a behaviour is labelled as an addiction. “Addiction” has become an umbrella term for countless problematic or maladaptive behaviours, as some authors have noted, which runs the risk of trivializing the severity of true addictions (Panova & Carbonell. J Behav Addict 2018;7:252-259).