Problematic internet use, impulsivity and inhibitory control

As mentioned above problematic internet use has been associated with substance-related and addictive disorders. The fundamental idea is that all these disorders share similar psychopathological origins, neuropathological and personality traits and thus, they could be conceived under the same spectrum (Shaffer et al., 2004). Despite Shaffer et al. (2000) criticism of conceptualising problematic internet use as a behaviour similar to other addictive disorders, emerging evidence alludes to commonalities between them (Grant et al., 2010;

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Leeman & Potenza, 2013). One of these areas of similarities pertains to the construct of impulsivity and inhibitory control for inhibitory control reflects a behavioural component of impulsivity. Impulsivity is a complex multidimensional construct which has been broadly characterized by a tendency to react fast without thinking and planning, as well as having the tendency to make decisions based on immediate outcomes without considering future consequences (Moeller, Barratt, Doughrty, Scmitz, & Swann, 2001). Definitions and measurements of impulsivity vary across studies. Aspects of impulsivity can be captured by either self-report measurements of personality, or behavioural tasks which can be combined with brain activation assessments and measures of behavioural and underlying mechanisms related to specific dimensions of impulsivity (Reynolds et al., 2006). For example, self-report personality questionnaires such as the Barratt Impulsiveness Scale-11 (BIS-11) (Patton, Stanford, & Barratt, 1995), the Sensation Seeking Scale (Zuckerman, Kolin, Price,

& Zoob, 1964) capture trait characteristics of impulsive behaviour. Some prominent behavioural tasks which have been used in the field of addictions are the Go/No-Go and Stop Signal tasks which gauge facets of impulsivity related to behavioural inhibition (Diamond, 2013) in the form of motor inhibition (withhold a response) and response inhibition to a prepotent learnt go signal respectively (Verbruggen & Logan, 2008). The Go/No-Go task requires participants to make quick and accurate responses to a series of stimuli that are associated with a “go” response while at the same time withhold their responses to stimuli that have been denoted as a “no-go” response. Similarly, in the Stop Signal task, participants are required to make quick and accurate responses to a series of stimuli associated with a

“go” response while at the same time withholding their responses to the same stimuli when a “no-go” signal is presented. Participants in this task have already initiated a response to the go signal when the withhold indication is subsequently presented. Finally, using these tasks while assessing electrical brain activity with Event Related Potentials (ERPs) can be a valuable indication of the underlying mechanisms associated with inhibitory control. An interesting advantage provided by investigation of brain activity is that it can identify similarities between different psychiatric disorders and thus, can provide valuable information of the etiology and course of a new disorder.

Research probing substance-related and addictive disorders provides a substantial source of evidence which has linked impairments in impulsivity and inhibitory control to be as a

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risk factor associated with their development and maintenance (Adams, Ataya, Attwood, &

Munafo, 2012; Billieux, Gay, Rochat, Khazaal, Zullino, & Van der Linden, 2010; Cheng, Lu, Han, Gonzalez-Vallejo, & Sui, 2012; Constantinou et al., 2010; Dawe & Loxton. 2004;

Dom, Hulstijn, & Sabbe, 2006; Fillmore & Rush, 2002; Finn, Bobova, Wehner, Fargo, &

Rickert, 2005; Fleming & Bartholow, 2014; Fuentes, Tavares, Artes, & Gorenstein, 2006;

Goudriaan, Oosterlaan, de Beurs, & van den Brink, 2005; Grano, Virtanen, Vahtera, Elovainio, & Kivimaki, 2004; Hair & Hampson, 2006; Kertzman et al., 2008; Kozink, Kollins, & McClernon, 2010; Kreusch, Vilenne, & Quertemont, 2013; López-Caneda, Holguín, Cadaveira, Corral, & Doallo, 2014; Lorains, Stout, Bradshaw, Dowling, & Enticott, 2014; Margin & Colder, 2007; Margin, MacLean, & Colder, 2007; Murphy, Taylor, &

Elliott, 2012; Noel et al., 2005, 2007; Pike, Stoops, Fillmore, & Rush, 2013; Verdejo-Garcia, Lawrence, & Clark, 2008; Verdejo-Garcia et al., 2012). Moreover, there is accumulating evidence that indicates abnormalities, both structurally and functionally, in brain areas which have been implicated as being associated with inhibitory control in addicted individuals (Cavedini, Riboldi, Keller, D'Annucci, & Bellodi, 2002, Feil et al., 2010; Franken, van Strien, Franzek, & van de Wetering, 2007; Hester & Garavan, 2004; Jentsch & Pennington, 2014; Kamarajan et al., 2004; Li et al., 2010; Li & Sinha, 2008; Luijten et al., 2013; Schulte, Muller-Oehring, Sullivan, & Pfefferbaum, 2012 ).

Similarly, emerging evidence has implicated elevated levels of impulsivity, inhibitory control as well as impairments in brain activity in these particular cognitive processes, as being associated with dysfunctional patterns of internet use (Billieux, & Van der Linden, 2012; Cao et al., 2007; Choi et al., 2014; Dong, Zhou, & Zhao, 2010, 2011; Dong et al., 2012; Kim et al., 2008; Lee et al., 2012; Meerkerk, van den Eijnden, Franken, & Garretsen, 2010; Mottranet & Fleming, 2009; Park et al., 2013; Yau et al., 2013; Zhou et al., 2010).

More specifically, Cao et al. (2007) found that adolescents who were diagnosed with problematic internet use had higher levels of impulsivity when assessed with BIS-11. They also had higher scores compared to the control group in their behavioural impulsivity as measured with the Stop Signal task. Moreover, Mottram and Fleming (2009) found that high levels of lack of pervasiveness, which refers to the inability to control behaviour and complete a task when distracting stimuli are present (an aspect of impulsivity), was a strong predictive factor for problematic internet use. Further, Meerkerk et al. (2010) conducted a

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study to examine the role of the constructs of sensitivity to reward, punishment, and impulsivity as factors underlying vulnerability regarding the development of problematic internet use. Overall, their results revealed only functional and dysfunctional impulsivity as well as sensitivity to punishment were good predictors for problematic internet use.

Functional impulsivity is conceptually similar to sensitivity to reward, whereas dysfunctional impulsivity refers to rash spontaneous impulse behaviour without giving consideration to consequences (Dawe & Loxton, 2004).

Activity in brain areas linked with inhibitory control as assessed by applying electrophysiological methodologies has confirmed the assumption of impairments in problematic internet users. More specifically, Dong et al. (2010) in a study examining event related brain potentials during the carrying out of the Go/No-Go task found that participants who were problematic internet users had a lower go/N200 amplitude, a higher no-go/P300 amplitude and a higher no-no-go/P300 peak latency compared to normal controls. The two measurements of ERPs in this particular task which is relevant to response inhibition, are the enhanced negative component in the conflicting stage (no-go) that peaks 200msec after the presentation of the stimuli and the enhanced P300 wave, which is a signal elicited after 300-500msec after the presentation of the stimulus. The implications of this study were that problematic internet users were impaired in their attention and ability to detect conflict as presented by the decreased N200 no-go amplitudes. Additionally, they had to increase their cognitive effort to solve the conflict arising in the incongruent condition as presented by the increased P300 amplitude. Overall, they displayed decreased efficacy in terms of information processing and response inhibition but on a behavioural level, no differences between group performances were observed. These data indicate that assessing underlying brain activation which served as the functioning of inhibitory control can provide an indication of the existence of impairments. These might, however, not have been so severe as to give rise to changes in behavioural performance but can be targeted earlier than otherwise would be possible with potential interventions. Similarly, Zhou et al. (2010) found no-go N200 lower amplitudes using the Go/No-Go task as were revealed in Dong et al.’s study. Dong, Zhou et al. (2011) conducted another study to assess brain activity, while participants both problematic and non-problematic internet users, were performing another task which assesses response inhibition, the coloured word Stroop task. The Stroop task

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requires participants to name the ink colour of a series of words. In the congruent condition, the colour name corresponds exactly to the colour of each as written out in letters; in the incongruent condition, the printed word and the actual colour of the letters are different.

When participants are required to report the ink colour of the word greater difficulty is experienced when they are facing the incongruent condition. Dong et al. found that in the incongruent condition problematic internet users showed a longer reaction time and made more response errors compared to the controls. Moreover, the ERP data showed reduced Medial Frontal Negativity (MFN) in the incongruent condition for the problematic internet users. MFN is the amplitude of the ERP elicited between 400 to 500msec after stimuli presentation and has been associated with conflict detection. These authors suggested that problematic internet users have impaired executive control as compared to non-problematic internet users.