Inhibitory control and decisional process in “new addictions”: the role of reward mechanism and the effect of inter-hemispheric lateralization in a gambling task

The term “new addictions” refers to all those phenomena that lead to behavioral dependencies, such as Pathological Gambling (PG) or the Internet Addiction Disorder (IAD). Recent data suggested that PG and IAD are associated to executive dysfunction, and hypersensitivity to immediate rewards, which are similar to those in substance abuse disorders. However, it is still not clear how the psychophysiological mechanisms underlying dysfunctional decision-making processes could affect the development of addictive behaviors in vulnerable individuals. The aim of this study was to investigate the cortical oscillations activity in healthy subjects in relation to the depressive mood, the motivational dimension and the vulnerability to Internet Addiction during a decisional risky task. To answer this question, 21 healthy subjects (aged M = 24.45, SD = 2.6) were required to perform the Iowa Gambling Task (IGT) and the Go/No-Go task (GNGt). The IGT simulates the real life decisions making; the GNGt was constructed using four different categories of background screen (neutral, control, online gambling and videogames) to elicit a gambling-like condition, while their cortical activity was registered by EEG. Then, they were given selfreport questionnaires to investigate the level of mood state using the Beck Depression Inventory - II (BDI II); the dispositional sensitivity of the Behavioral Inhibition System (BIS) and the activation of the Behavioral Approach System (BAS) (BIS/BAS scale); the State-Trait Anxiety Inventory (STAI-Y); and the Internet Addiction Test (IAT). It was hypothesized that higher depressive and anxiety levels and lower inhibitory abilities to control more automatic processes could significantly correlate with Internet abuse. Moreover, the differences in the oscillation activity over the left or right hemisphere in relation to winning or losing conditions and to inhibition of control could characterise a typical profile of vulnerability in Internet Addiction. Results revealed a positive correlation between the BDI-II and IAT; the BDI-II and the STAI-Y. Thus, a depressive mood seemed to accompany people with internet abuse. The BAS-Reward scale seems to be predictive of a reduction in response times during the GNGt, when the task was played with a screen simulating an “online gambling”. Subjects who received high scores on the BDI-II also had a worse performance in GNGt, and then a difficulty of inhibition of control. From the analysis of the power band it has emerged an increase of delta, theta and alpha, in the right hemisphere while choosing disadvantageous decks during IGT, and while playing the GNGt with a “gambling” screen. This result can be ascribed to an increased of left PFC activity linked to the choice of more risky and “gambling” condition which may be considered as a biomarker of dysfunctional behavior in people at risk IAD.