Problematic internet use and psychiatric co-morbidity in a population of Japanese adult psychiatric patients

BACKGROUND: Many studies reported the high prevalence of problematic internet use (PIU) among adolescents (13–50%), and PIU was associated with various psychiatric symptoms. In contrast, only a few studies investigated the prevalence among the adult population (6%). This study aimed to investigate the prevalence of PIU and psychiatric co-morbidity among adult psychiatric patients. METHODS: Three hundred thirty-three adult psychiatric patients were recruited over a 3-month period. Two hundred thirty-one of them completed the survey (response rate: 69.4%, 231/333; Male/Female/Transgender: 90/139/2; mean age = 42.2). We divided participants into “normal internet users” and “problematic internet users” using a combination of Young’s Internet Addiction Test (IAT) and the Compulsive Internet Use Scale (CIUS). Demographic data and comorbid psychiatric symptoms were compared between the two groups using self-rating scales measuring insomnia (Athens Insomnia Scale, AIS), depression (Beck Depression Inventory, BDI), anxiety (State-trait Anxiety Inventory, STAI), attention deficit hyperactivity disorder (ADHD) (Adult ADHD Self-report Scale, ASRS), autism (Autism Spectrum Quotient, AQ), obsessive-compulsive disorder (OCD) (Obsessive-Compulsive Inventory, OCI), social anxiety disorder (SAD) (Liebowitz Social Anxiety Scale, LSAS), alcohol abuse, and impulsivity (Barratt Impulsive Scale, BIS). RESULTS: Among 231 respondents, 58 (25.1%) were defined as problematic internet users, as they scored high on the IAT (40 or more) or CIUS (21 or more). The age of problematic internet users was significantly lower than that of normal internet users (p < 0.001, Mann–Whitney U test). The problematic internet users scored significantly higher on scales measuring sleep problems (AIS, 8.8 for problematic internet users vs 6.3 for normal internet users, p < 0.001), depression (BDI, 27.4 vs 18.3, p < 0.001), trait anxiety (STAI, 61.8 vs 53.9, p < 0.001), ADHD (ASRS, part A 3.1 vs 1.8 and part B 3.5 vs 1.8, p < 0.001), autism (AQ, 25.9 vs 21.6, p < 0.001), OCD (OCI, 63.2 vs 36.3, p < 0.001), SAD (LSAS, 71.4 vs 54.0, p < 0.001), and impulsivity (BIS, 67.4 vs 63.5, p = 0.004). CONCLUSIONS: The prevalence of PIU among adult psychiatric patients is relatively high. As previous studies reported in the general population, lower age and psychiatric comorbidity were associated with PIU among adult psychiatric patients. More research is needed to determine any causal relations between PIU and psychopathological illnesses. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12888-018-1588-z) contains supplementary material, which is available to authorized users.