The co-existence of gaming disorder (GD) with other mental health problems has been widely reported. Despite the growing research interest in the comorbidity of GD with attention-deficit/hyperactivity disorder (ADHD), to date, no quantitative synthesis has been performed. The present study comprised a systematic literature search using Scopus, Science Direct, Web of Science, and PubMed databases. Three types of studies were included in the analyses: studies reporting (i) correlation coefficients…