Examination of addiction and level of engagement in potentially addictive activities : gambling, video-arcade games, computer games and the internet

Recent advances in the field of addiction have given greater emphasis to subjective experience and compulsive behaviour. This signifies an important shift from focusing on the object of addiction to acknowledging that behaviours, which can induce changes in physical arousal and subjective experience, have the propensity to be overused and lead to addiction. Gambling, video-arcade games, computer games, and the Internet have therefore been identified as potentially addictive activities, which like drug use, also exist on a continuum of addiction, ranging from no symptoms of addiction to addiction. Researchers have also emphasised the need to distinguish high engagement in activities and addiction (e.g., Charlton, 2002). The aims of the present research are therefore to extend current knowledge on the level of participation and prevalence of addiction to these four activities and to investigate continuum hypotheses of addiction. Study 1 focused on establishing the level of engagement and prevalence of students endorsing symptoms of addiction due to their involvement in gambling, videoarcade games, computer games, and the Internet. A sample of 1762 (845 female) school students from rural and urban Tasmanian schools (Grades 4 to 12) and 709 (509 female) university students participated in Study 1. Lifetime participation and frequency and duration of engagement in on-line games and the Internet was higher amongst this sample of Australian students compared to previous research conducted on youth (e.g., Tejeiro Salguero & Bersabe Moran, 2002; Wang, 2001). A lower percentage of students met the modified criteria for addiction compared to previous studies, however, the prevalence of sub-clinical computer game and Internet addiction was higher than that reported by past researchers (e.g., Chou & Hsiao, 2000; Johansson & Gatestam, 2004). Risk factors found to predict addiction significantly (e.g., high engagement) were consistent with previous studies (e.g., Chou & Hsiao, 2000; Clarke & Rossen, 2000; Johansson & Gatestam, 2004). The identification of risk factors associated with subclinical and clinical addiction has implications for future prevention programs. Three continuum hypotheses were investigated in Studies 2, 3 and 4; low engagement through to addiction, continuum of increasing engagement and addiction symptomatology, and continuum of addiction symptomatology. In Study 2 (N = 80), the P3a and P3b components of the ERP were examined as these components are proposed to act as a trait marker for substance addiction and index externalizing disorders of disinhibition (P3b only). A difficult discrimination three-stimulus visual oddball paradigm was employed to elicit maximum fronto-central P3a to the non-target distractor stimuli and centro-parietal P3b to targets. It was hypothesized that both P3a and P3b amplitude would be sequentially reduced in participants with progressively greater engagement and symptoms of addiction. In Study 3 (N = 79) the mismatch negativity (MMN) component, known to index impulsivity, alcoholism, and CNS disinhibition and hyper-excitability, was examined using a two-stimulus unattended passive auditory oddball task. It was hypothesized that, compared to the P3a and P3b results, the inverse relationship would be reflected in MMN amplitude. A significant widespread reduction in P3a amplitude was found in Study 2, only among participants with either a sub-clinical or clinical level of addiction compared to those with no symptoms of addiction. Significant results were established for each continuum hypothesis when examining the amplitude of the P3b component. P3b amplitude indexed a dichotomous distinction between lower levels of engagement and/or no symptoms of addiction (non-clinical group), and participants with either a sub-clinical or clinical level of addiction and/or high level of engagement in activity(ies). Findings for both P3a and P3b amplitude indicate that the critical factor was not whether a diagnosis of addiction was met, but rather whether students did or did not experience some symptoms of addiction. These reductions in P3a and P3b amplitude among students with a sub-clinical level of addiction are consistent with suggestions that genetic trait markers for risk of addiction should also be present among sub-clinical populations (Slutske, Eisen, True, Lyons, Goldberg & Tsuang, 2000). In line with past research investigating substance addiction, these findings suggest that participants with lower levels of engagement and/or no addictive symptoms had more resources available to perform the task than participants with either a sub-clinical presentation or diagnosis of addiction. However, in contrast to previous studies of participants with substance addiction, findings from Study 3 revealed that the amplitude of the MMN was not significantly higher among those with addiction, sub-clinical addiction and/or high engagement. In accordance with MMN findings, Study 4 established that the Addicted group were not significantly different to other participants according to extraversion or neuroticism dimensions, suggesting therefore that this sample may not be as impulsive as individuals with substance addiction. The absence of significant MMN amplitude differences suggests that reductions in P3a and P3b amplitude recorded for groups with a sub-clinical, or above, level of addiction are specifically related to differences in cognitive processing that requires attentional resources and not to pre-attentive automatic processing of incoming stimuli. Furthermore, as the Addicted sample did not display significantly higher traits of extra version or neurotic ism in conjunction with the absence of increased MMN amplitude, it appears that these forms of behavioural addiction are not related to impulsivity, and therefore suggests that they are not externalizing behaviours related to frontal disinhibition. Further research investigating the neurophysiology, psychophysiology and possible existence of a genetic vulnerability to these behavioural addictions is warranted, given that the prevalence of a sub-clinical addiction to computer games and the Internet is increasing among the student population