Dr Susumu Higuchi has no doubt about the mental health risks posed by on-line gaming. He heads the Kurihama Medical and Addiction Centre in Kanagawa Prefecture, Japan, which started the country’s first programme for internet addiction in 2011. There are now 84 nationwide. Higuchi has watched the number of patients addicted to on-line gaming steadily grow. “Of the 269 patients we now see for internet addiction, 241 have gaming disorder as their principal addiction”, he says. “Of those, 215 are males.” The patients Higuchi sees display a range of symptoms, but are generally unable to limit the time they spend gaming and continue to play despite negative consequences, such as dropping out of school (almost three quarters of the patients are students) or losing a job.

No national survey of gaming disorder has been undertaken in Japan. However, a recent national survey of the broader category of “internet addiction” reported that approximately 1.82 million males 20 years of age and older, were living with an internet addiction in 2018, almost three times the number reported in 2013. The same survey reported 1.3 million adult females living with internet addiction, up from 0.5 million in 2013.

Higuchi co-authored a recent literature review - Cross-sectional and longitudinal epidemiological studies of internet gaming disorder – that found a prevalence of internet gaming disorder in the samples reviewed ranging from 0.7% to 27.5%. “The literature review revealed that geographical region made little difference to prevalence,” says Vladimir Poznyak, an expert on substance use and addictive behaviours at the World Health Organization (WHO), who points to several surveys showing internet gaming disorder prevalence between 1%-10% in Europe and North America. “Because of differences in survey quality and comparability, the exact size and nature of that problem is yet to be defined,” he says, “but it is clear there is a problem.”