Tolerance and withdrawal symptoms may not be helpful to enhance understanding of behavioural addictions

The importance attached to tolerance and withdrawal symptoms in the conceptualization of addiction reflects the prominence of theories that posit neuroadaptation to the presence of a drug [1], and suggest that drug use persists because of negative reinforcement, i.e. as an effort to avoid the unpleasant withdrawal symptoms [2]. Given that tolerance and withdrawal symptoms do not always occur in addiction, they have not been included in the recent general definitions of addiction [3–5]. However, these phenomena are often incorporated into the conceptualization of behavioural addictions. For example, one model [6] postulates that tolerance and withdrawal symptoms are mandatory for any behaviour to be considered addictive. In behavioural addictions, tolerance is usually defined in a way that superficially resembles its counterpart in substance addictions, i.e. dose escalation to achieve the same initial effect. Thus, tolerance is portrayed as an increase in various aspects of the activity (frequency, intensity, duration, time spent, money spent) to achieve the desired effect, satisfaction or excitement. Occasionally, it is described as a need for the latest or more powerful equipment (e.g. mobile phones, computers, software) to produce the desired effect or excitement [7,8]. The diagnostic criteria for internet gaming disorder [9] do not state the purpose of an increase in activity engagement, implying that any such increase denotes tolerance. Nevertheless, increased activity engagement and a need for better equipment in behavioural addictions do not necessarily reflect tolerance [10,11], which underscores the importance of assessing the contextual aspects of these phenomena. Withdrawal symptoms in behavioural addictions have usually been described as emotional states (irritability, restlessness, anger, moodiness, sadness, guilt, anxiety, feeling tense) that occur when activity engagement is thwarted. In internet gaming disorder, withdrawal symptoms can be easily mistaken for reactions to an externally imposed gaming deprivation or for craving for gaming [12]. There have been no reports of severe physical withdrawal symptoms in behavioural addictions [13], and a few studies reporting physical withdrawal symptoms in pathological gambling [14,15] had significant methodological shortcomings. Withdrawal states occurring upon abrupt drug cessation comprise both physical and emotional symptoms, with the latter hypothesized to contribute more to the motivation to continue using drugs because of the short-lasting effects of the former [2]. In pathological gambling, however, emotional withdrawal symptoms, as well as tolerance, were not found to play an important role in maintaining this behavioural addiction [16]. ‘Borrowing’ tolerance and withdrawal from substance addictions might have been driven by a need to ‘legitimize’ behavioural addictions. This was unnecessary, because these phenomena and theories suggesting that they are important for addiction have not been able to account fully for either type of addiction [5]. The alternative is to conceptualize behavioural addictions via specific factors that explain more clearly attachment to the particular activity [17] and maintenance of addictive behaviour. In pathological gambling, these factors were identified as the negative feelings associated with gambling losses, shortage of money and the need to be secretive about gambling [16]. The task is to ascertain factors that provide an adequate account for each behavioural addiction. None.