Müller & Schumann (M&S) provide a new framework for the understanding of non-addictive substance use, acknowledging the significance of a developmental perspective. It seems important to broaden and deepen this framework theory with respect to the specific characteristics of adolescent drug use to better understand the preconditions of adult non-addictive drug instrumentalization. Adolescence is a developmental period characterized by an increase in novelty-seeking, risk-taking, and emotional reactivity. Experimental and recreational drug use usually starts during this period, with the ages 10–16 being the high-risk period for substance use onset and the subsequent three years for transitions to regular use and abuse (Wittchen et al. Reference Wittchen, Behrendt, Hofler, Perkonigg, Lieb, Buhringer and Beesdo2008). However, early initiation of substance use has also consistently been shown to be associated with higher lifetime consumption, with more risky patterns of use, and with the earlier onset, longer duration, and higher severity of drug dependence later in life (Behrendt et al. Reference Behrendt, Wittchen, Hofler, Lieb and Beesdo2009; Grant & Dawson Reference Grant and Dawson1997). Various factors may account for this association.

Adolescence is characterized by a maturational and functional imbalance between already relatively mature limbic systems, implicated in motivational and emotional processing, and functionally still relatively immature prefrontal regions, mediating top-down modulation of affective and motivational processing by cognitive control processes. This imbalance may bias adolescents, particularly in emotionally salient situations, to seek immediate, rather than long-term gains, and it may explain their increase in risky decision making, their emotional reactivity, and their heightened responsiveness to rewards (Casey & Jones Reference Casey and Jones2010). Accordingly, behavioral observations indicating a higher salience of reward and increased susceptibility to the positive reinforcing properties of alcohol and other drugs are supplemented by studies demonstrating elevated neuronal responses of reward-related brain regions in anticipation of reward in adolescents compared to children and adults (van Leijenhorst et al. Reference van Leijenhorst, Zanolie, Van Meel, Westenberg, Rombouts and Crone2010).

Moreover, the adolescent brain appears to be more vulnerable to the neurotoxic effects of drugs, particularly in regions that mediate learning and memory processes (Brown & Tapert Reference Brown and Tapert2004). Repeated drug use may also more easily sensitize an already enhanced reward response, thereby inducing an increased incentive salience of drug-related stimuli (Robinson & Berridge Reference Robinson and Berridge2008). Such probable drug-induced changes may promote a faster development of addiction in adolescent- as compared with adult-onset users. For example, in animal studies, exposure to nicotine during adolescence, but not during adulthood, leads to significant changes in nicotine receptors in rodents and to an increased reinforcement value for nicotine later in life (Adriani et al. Reference Adriani, Spijker, Deroche-Gamonet, Laviola, Le Moal, Smit and Piazza2003). Prospective studies also indicate that drug-induced adolescent brain changes may directly interfere with the development of mature cognitive and behavioral functioning and may impede the adaptation to developmental challenges during adolescence.

Compared with that of adults, adolescent behavior is more strongly driven by social environment, particularly during initiation and early phases of drug use (Kendler et al. Reference Kendler, Schmitt, Aggen and Prescott2008). During adolescence, interactions with peers become increasingly important and exert a much stronger impact on decision making than they do in adulthood (Spear Reference Spear2002). The association between social influences of peers and adolescent substance use is well established. Peer effects account in particular for risky consumption patterns such as binge drinking impeding non-addictive controlled drug instrumentalization. Various studies indicate that the reward value of drugs of abuse may be affected by social context more strongly in adolescence than in adulthood (Doremus-Fitzwater et al. Reference Doremus-Fitzwater, Varlinskaya and Spear2010). Because coping abilities are still poorly developed during this developmental period, adolescents are at particular risk to “over-instrumentalize” drug use to manage stress related with significant life transitions during adolescence instead of acquiring mature coping skills (DeWit et al. Reference DeWit, Adlaf, Offord and Ogborne2000).

Thus, experimentation with drugs may rather support the use of substances as a maladaptive coping strategy to adapt to life challenges. For example, Buchmann et al. (Reference Buchmann, Schmid, Blomeyer, Zimmermann, Jennen-Steinmetz, Schmidt, Esser, Banaschewski, Mann and Laucht2010) provided evidence showing that the initiation of alcohol use in early adolescence promotes alcohol use with the objective of coping with unpleasant emotions during young adulthood. The experience of pleasant drug effects, such as relaxation and cheerfulness, may emerge as a fast-reinforcing strategy to deal with stress and to foster the continued and increased drug use, particularly when exposed to stress (Blomeyer et al. Reference Blomeyer, Buchmann, Schmid, Jennen-Steinmetz, Schmidt, Banaschewski and Laucht2011) and being at genetic risk (Blomeyer et al. Reference Blomeyer, Treutlein, Esser, Schmidt, Schumann and Laucht2008; Laucht et al. Reference Laucht, Treutlein, Schmid, Blomeyer, Becker, Buchmann, Schmidt, Esser, Jennen-Steinmetz, Rietschel, Zimmermann and Banaschewski2009). Accordingly, adverse life events during childhood increase the likelihood for early substance involvement and subsequent addiction (Andersen & Teicher Reference Andersen and Teicher2009).

The aforementioned restraints of a stable, goal-oriented drug instrumentalization apply particularly to adolescents with psychiatric disorders. Numerous studies have highlighted that individuals with externalizing disorders are at higher risk for both early initiation and subsequent addiction (Laucht et al. Reference Laucht, Hohm, Esser, Schmidt and Becker2007; Molina & Pelham Reference Molina and Pelham2003). Executive function and motivational deficits resulting in increased impulsivity and emotional reactivity might interfere with non-addictive drug use. Hence, high impulsivity was found to predict the switch to more habitual and compulsive drug use in rodents (Belin et al. Reference Belin, Mar, Dalley, Robbins and Everitt2008).

Regarding implications for drug policy, prevention programs for those at younger ages or those being particularly vulnerable should aim to delay age at initiation to prevent substance use disorders, with establishing youth protection laws being particularly relevant (Buchmann et al. Reference Buchmann, Schmid, Blomeyer, Becker, Treutlein, Zimmermann, Jennen-Steinmetz, Schmidt, Esser, Banaschewski, Rietschel, Schumann and Laucht2009). Programs should teach alternative and more adequate coping strategies and general life stabilization strategies. Moreover, programs should take into account the strong impact of social environmental factors on adolescent behavior. Hence, good parental monitoring associated with positive parental involvement has been found to be effective to prevent alcohol abuse (Ryan et al. Reference Ryan, Jorm and Lubman2010), particularly in genetically vulnerable subgroups (Laucht et al. Reference Laucht, Blomeyer, Buchmann, Treutlein, Schmidt, Esser, Jennen-Steinmetz, Rietschel, Zimmermann and Banaschewski2011). In addition, the parental model of responsible drug instrumentalization has proven to be essential for the offspring's orientation. Recently, an Australian expert group developed guidelines for parents on their influence to prevent their child's drinking (Ryan et al. Reference Ryan, Jorm, Kelly, Hart, Morgan and Lubman2011). In the course of development, peers become increasingly important for adolescent consumption patterns, forming the reference frame for the perception of “normal” amounts of alcohol used. Most adolescents are not aware of this mechanism and tend to overestimate their friends' drinking behavior while underestimating their own. Here, campaigns establishing responsible drinking norms in the target group are promising, if located in an adequate surrounding (Scribner et al. Reference Scribner, Theall, Mason, Simonsen, Schneider, Towvim and Dejong2011).