Video gaming can be addictive in the same way as cocaine or gambling, the World Health Organization (WHO) said Monday in a much anticipated update of the International Classification of Diseases (ICD-11).
The WHO's ICD, a reference bible of recognized and diagnosable diseases, describes addiction to digital and video gaming as "a pattern of persistent or recurrent gaming behavior" that becomes so extensive it "takes precedence over other life interests."
Online and offline "gaming disorder" is grouped with "disorders due to substance use or addictive behaviors" in the ICD's 11th edition, the first major revision in nearly three decades.
The wording of the new entries has been known since January, when the WHO announced problem gaming would be recognized as a pathological condition.
Symptomatic behavior must continue for at least a year before it is considered dangerously unhealthy, according to the new classification.
The WHO's expert on mental health and substance abuse, Shekhar Saxena, said some of the worst cases seen in global research were of gamers playing for up to 20 hours a day, forgoing sleep, meals, work or school and other daily activities.
Some 2.5 billion people -- one-in-three worldwide -- play some form of free-to-play screen game, especially on cell phones, but the disorder only affects a "small minority," said Saxena.
"We are not saying that all gaming is pathological. This is an occasional or transitory behavior," he said, adding that only if such behavior persists for around a year could a potential diagnosis of a disorder be made.
The games industry raked in $108 billion worldwide in 2017, more than double movie box-office receipts, according to Superdata, which tracks the games and interactive media sector.
Nearly 40 percent of those sales are in east Asia, especially China and South Korea. Other important markets include the United States, Britain, France, Germany and Brazil.
In South Korea and the United States, clinics have sprung up to treat video game addiction, along with community and online support groups.
So-called "shooter games" such as "Fortnite" -- described on the support website Game Quitters as the "hottest game in the world" -- are either played online or on offline consoles.
The inclusion of "gaming disorder" in WHO's revised catalogue of diseases met with resistance, both from industry and some experts.
"The WHO process lacks transparency, is deeply flawed and lacks scientific support," Michael Gallagher, president and CEO of the Entertainment Software Association, said in a statement in March.
In a study to be published in the Journal of Behavioral Addictions, a group of 36 researchers said there was insufficent evidence to warrant the new category.
"Given the gravity of diagnostic classification and its wider social impact, we urge our colleagues at the WHO to err on the side of caution for now and postpone the formalization," they wrote in a study reviewing academic literature.
The ICD identifies about 55,000 separate injuries, diseases, conditions and causes of death, and is widely used as a benchmark for diagnoses and health insurance.
"It enables us to understand so much about what makes people get sick and die, and to take action to prevent suffering and save lives," WHO Director-General Tedros Adhanom Ghebreyesus said in a statement.
This latest version - known as ICD-11 - is completely electronic for the first time, in an effort to make it more accessible to doctors and other health workers around the world.
ICD-11 also includes changes to sexual health classifications. Previous editions had categorized sexual dysfunction and gender incongruence, for example, under mental health conditions, while in ICD-11 these move to the sexual health section. The latest edition also has a new chapter on traditional medicine.
The updated ICD is scheduled to be presented to WHO member states at their annual World Health Assembly in May 2019 for adoption in January 2022, the WHO said in a statement.