There is no doubt that excessive gambling can cause a huge mental, personal, and financial toll for the gambler and the members of their family. The nature of excessive gambling and whether it constitutes a disorder has been the subject of much research, debate, and controversy in recent years. Originally included with impulse control disorders as "pathological gambling" in the American Diagnostic and Statistical Manual (DSM), it has in the most recent edition, DSM-5, been included in the addictive disorders section with various psychoactive substance use disorders. The criteria for what is termed "gambling disorder" in DSM-5 now share many of those with substance use disorders, including features such as priority given to gambling over other life activities and responsibilities, urges to gamble, and the need to gamble increasing amounts.
There is also increasing acceptance of withdrawal states when gambling suddenly ceases because the person is coerced to or there is no further money with which to gamble. A distinct criterion is "chasing" previous losses by gambling in an effort to try and recoup them, a phenomenon that does not have an exact counterpart in substance disorders. The associations and comorbidities of gambling disorder with predisposing factors and associated psychiatric disorders show a high level of similarity. Gambling disorder has now been included in the latest (eleventh) revision of the International Classification of Diseases (ICD-11), published by the World Health Organization.
Research into the features of excessive gaming is of more recent origin and reflects the vast array of internet-based/online games that have been devised over the past 10-15 years. These harness the power of the internet to maximise their interactivity, and offer the ability for gamers to form teams in the online environment and play against each other often for most of the waking day. An examination of the various features of online gaming indicates that excessive online gaming conforms to behavioural addictions, its central features being impaired control over gaming, priority given to it over other activities and responsibilities, and continuation of gaming despite harmful consequences—much as is seen in substance dependence. Internet gaming disorder is included in DSM-5 as a candidate diagnosis. Gaming disorder is included in the chapter of disorders in the draft version of the ICD-11 due to substance use and addictive behaviours. Physiological features of tolerance and withdrawal have been described in gaming disorder, but given the infancy of the literature specifically on these phenomena it may be premature to include them as diagnostic features at the present time.
These developments in the classification systems are important because they identify gambling and gaming disorder and their addictive nature as significant health problems. Already, treatments for substance disorders, such as relapse prevention therapies and medications working on the reward and reinforcement systems such as naltrexone, are being applied to both of these disorders. A public health perspective incorporating prevention and health-promoting public policy measures would also be valuable, as they have contributed so much to the decline in cigarette smoking and the reduction of alcohol-related harm in many countries.
In Addiction Medicine, Second Edition, new chapters have been incorporated on gambling disorder and gaming disorder, as well as a chapter examining the features, comorbidities, and clinical management approaches for a range of other behavioural disorders with addictive features. It may well be that as research advances, more evidence will emerge of other forms of excessive consumption that can be properly identified as addictive disorders.