Gambling disorder is characterized by persistent and recurrent problematic gambling behavior that leads to clinically significant impairment or distress (American Psychiatric Association et al., 2013, Potenza et al., 2019). It is characterized by a loss of control over repeated gambling activities, and it results in serious consequences for individuals and society; therefore, gambling disorder is an important issue in both psychiatry and public health (Wardle et al., 2024). Individuals with gambling disorders are known for their strong tendency to chase losses and risk relationships and career opportunities; however, this is a behavioral addiction, and affected individuals have low motivation for treatment. The one-year prevalence of gambling disorder in the general population is 0.2–0.3 %, with men being more likely to be affected than women (DSM, 2013). Furthermore, gambling disorder often coexists with other psychiatric disorders, with 37 % of affected individuals reporting suicidal ideation and 11 % reporting suicide attempts (Manning et al., 2015). In Japan, gambling disorder is a major social issue that is exacerbated by traditional forms of gambling, such as pachinko and horse racing, as well as the increasing prevalence of online gambling, which leads to a greater risk of gambling disorder (Mori and Goto, 2020).

Japan has recently been exploring a large-scale casino initiative, prompting concerns about a potential increase in the prevalence of gambling addiction (Mori and Goto, 2020, Hayano et al., 2021). Although the economic advantages of introducing casinos have been highlighted, the risk of heightened addiction cases remains a significant issue.

In recent years, the relationship between gambling disorder and attention-deficit/hyperactivity disorder (ADHD), a type of developmental disorder, has gained attention (Retz et al., 2016). ADHD, which is characterized by hyperactivity, impulsivity, and attention deficits, affects 5.9 % of young individuals and 2.5 % of adults (Faraone et al., 2021). Neurotransmitter abnormalities and dysfunction in the prefrontal cortex are thought to contribute to impulsivity and impaired decision-making (Hauser et al., 2014, Tripp and Wickens, 2009). Notably, one of the core symptoms of ADHD – namely, strong impulsivity – is observed in 69 % of individuals with this condition (Wilens et al., 2009). The impulsive characteristics of individuals with ADHD often lead to a lack of planning and a strong preference for immediate rewards, which may facilitate gambling behaviors and elevate the risk of developing gambling disorder. This tendency to devalue delayed rewards is known as delay discounting. In particular, individuals with ADHD have been reported to exhibit a pronounced decrease in the perceived value of rewards as the waiting time for those rewards increases (Dixon et al., 2003, Jackson and MacKillop, 2016). Approximately 20 % of individuals with gambling disorder also have comorbid ADHD (Specker et al., 1995), thus highlighting the need for careful consideration and preventive measures. To date, treatment approaches such as cognitive-behavioral therapy and group psychotherapy have been developed for the treatment of gambling disorder, however preventive measures remain insufficient (Menchon et al., 2018). Furthermore, there is a lack of clarity with respect to the predictive factors for gambling disorder among individuals with ADHD symptoms, and there is limited evidence based on real-world data.

This study aims to identify predictive factors for problem gambling and to examine the relationship between ADHD symptoms and gambling behavior. We used data from a large-scale internet cohort study (the Japan Society and New Tobacco internet Survey, or JASTIS study) (Tabuchi et al., 2019) to investigate various gambling experiences and characteristics that contribute to the increased risk of problem gambling in individuals with ADHD symptoms.