In addition, most studies only provide data concerning the prevalence and specific interactions with sociodemographic variables without referring to a theoretical model. Therefore, little is known regarding the decision-making process among CE users, and a theoretical framework guiding empirical investigations is needed [7] , [16] – [18] .

The current prevalence rate of CE drug use is unknown. However, one poll found that 20% of the surveyed readers of Nature magazine [10] used drugs during their lifetime to augment performance. In another survey, 23% of physicians in North America were willing to use cognitive enhancers of proven efficacy if they were approved for use and had no severe associated risks [12] . For students, surveys suggest a lifetime prevalence of CE drug use ranging from 3% to 11% in the U.S. [13] and 0.7% to 4.5% in Germany [14] , [15] .

University students and teachers can be seen as populations at risk for CE drugs use [10] , as success in academia depends on “brainpower”, and a need to perform at high levels may have increased due to competition over the last few decades (e.g., [11] ).

Some authors predict that CE will be a forthcoming trend that will shape history and herald a 21st century of neuroscience [8] . One reason for this trend might be increasing pressure at work due to increased competition and workload [9] . Therefore, CE can be understood as an instrumental adaption to cope with these demands [4] .

CE can be defined as “the amplification or extension of [the] core capacities of the mind through improvement or [the] augmentation of internal […] information processing systems” ( [1] , p. 311). Healthy individuals may perceive CE drug use as a benefit-seeking strategy to enhance their cognitive abilities [2] – [4] . Potential cognitive enhancing medications include methylphenidate, (dextro-) amphetamine, donepezil, and modafinil [5] , [6] . These drugs are prescribed as treatment for a variety of disorders, including attention deficit hyperactivity disorder (ADHD), postural orthostatic tachycardia syndrome, Alzheimer’s disease or dementia, shift work sleep disorder, and narcolepsy (e.g., [4] , [7] ).

The Mechanisms of Using Performance Enhancing Drugs

We refer to the self-medication hypothesis [19], [20], which proposes that individuals apply strategies to reduce their cognitive interference or compensate for certain deficits despite the potentially negative aspects of medication [21]. This non-formalized idea approximates the general approach of the classical Rational Choice Theory (RCT), which assumes that actors are utility maximizers who make decisions by weighing the pros and cons of possible action alternatives [22]–[24]. We adopt this idea to explain CE drug use (cf. [4]), as consuming performance-enhancing drugs is based on a decision-making process, which includes the following instrumental incentives: 1) the benefit of using CE medication to increase mental performance; 2) the probability of achieving this benefit; 3) the costs associated with CE drug consumption (i.e., the potential side effects); and 4) the probability of these costs.

The desired goal of CE drug use is to increase cognitive performance relative to an actual baseline state [1] by enhancing concentration, allowing students to study for more hours [25] or increasing working memory performance [26]. Boosting one’s self-esteem or the desire to improve one’s position relative to others in competition for prospective jobs and other assets [1], [27] might be additional reasons. Studies have shown that a low student grade point average and highly competitive admission criteria at colleges are associated with higher rates of the non-medical use of prescription stimulants [17]. This finding might indicatethat CE drug use is a strategy to attain success [15]. In addition, CE drugs might be a means to cope with stressors and increase personal performance [16].In general, the benefits of CE drug use are small-to-moderate for healthy individuals [1], [28], and a diminishing return can be expected [26], [29], [30].

However, the effects vary widely across individuals (e.g., [26], [29]–[33]), and high-performing individuals benefit the least from CE drugs [29], [30], [34]. Consequently, the desired benefits occur with a certain likelihood.

For healthy individuals, concerns exist regarding the potential side effects and long-term health consequences of CE drug use (e.g., fatal arrhythmias, excitotoxicity, emesis, sexual dysfunction, addiction, depression, sleep difficulties, reduced appetite and weight loss as well as weight gain, hypertension, headaches, high blood pressure, and even changes in personality; [21], [27], [30], [34]–[37]). These costs may outweigh the benefits [5]. Counterfeit medication purchased on the Internet is particularly associated with risks as well as unintended overdosing by self-medication [26], [34] and risks emerging from the interactions of these drugs with other medications [37]. These negative consequences of off-label use are largely unknown for healthy individuals [5], [10]. Following the self-medication hypothesis, actors might be willing to accept the negative effects of a substance in exchange for the chance to achieve a desirable state [10], [19]. Some evidence shows that expected side effects of CE drugs reduce the frequency of their use [15]. However, additional research is needed concerning the extent to which side effects influence the decision-making process, as little is known about how respondents react to hints or information regarding drug characteristics [28].

These side effects do not occur with certainty, but they do occur with a specific probability. For example, Wezenberg et al. [38] found that 6 out of 10 healthy users of ampakine farampator (a treatment of Alzheimer’s disease and schizophrenia that can be used as a CE drug) suffered from headaches. This type of information is outlined in instructional leaflets for medically prescribed drugs; however the validity of such information for healthy users is unclear. Therefore, individuals must evaluate the likelihood of side effects before engaging in self-medication [27]. Rejecting or verifying the assumption of “naive users” will improve our understanding of the mechanisms that underlie CE drug use [39].

In addition to the variables considered by classical RCT, the normative dimensions of CE drug use (cf. [8], [28], [40]) must be explored for the following reasons: CE drugs might be perceived as an unfair means to gain advantages relative to others, which may place pressure on non-users to also use drugs [1], [21] and may infringe on others’ freedom of choice [8]. Furthermore, unequal access (e.g., because of financial restrictions) can violate the norms of fairness [3]. In addition, the violation of authenticity norms has been discussed via the implication that “native or achieved excellence has a higher worth than talent that is bought” ([1], p. 326). Using medication for another purpose might be socially prohibited or taboo and can be regarded as a socially undesirable abuse of drugs. Actually, little is known about how potential users make decisions with regard to this normative dimension [28].

According to Hechter and Opp [41], social norms can be defined as moral imperatives (i.e., social actions that should (or should not) be processed without taking in account consequences for the actor) or more generally as guidelines for individual actions in the absence of moral imperatives. We propose that the social norms that prohibit CE drug use have not been internalized to the same degree across all actors.

Some scholars argue that following or violating a norm can be regarded as rational behavior [42], [43]. Although breaking a norm can result in internal penalties such as psychological costs, following an internalized norm can result in intrinsic rewards [43], [44]. Several studies have provided evidence that norms are crucial determinants of behavior (e.g., [45], [46]). Considering internalized norms as psychological incentives breaks with the traditional assumption in RCT that actors hold preferences only for tangible or “hard” incentives [47]. Extending RCT models using the concepts of social psychology is helpful in predicting behavior [48]. A person’s willingness to take CE drugs is expected to decrease as internalized norms against CE use become stronger.

Other scholars posit that social norms should not be regarded as a part of a rational decision-making process [49], [50], i.e., by prescribing behavior in unconditional and non-outcome-oriented ways [51]–[53]. If a potential action is classified as “wrong” due to a particular norm, then this action is more likely to be removed from the agenda. Therefore, norms function as filters for non-appropriate alternatives (also see [54], p. 75). Thus, deliberation no longer becomes necessary, and benefits are weighted down, completely ignored, or the deterring effect of the costs increases [52], [55]. Actors often rely on proven and well-known strategies without much consideration of alternate strategies (e.g., a rule of thumb or social norm) to reduce the costs of in-depth deliberation [52], [55]. The stronger the internalized norm, the less individuals deliberate on the costs and benefits of CE drug use, and the more likely individuals are to refrain from their use.

The single elements of the decision-making process according to classical RCT can be summarized in an expected utility term (U = q * B – p * C) where q is the probability that the drug works, B is the increase in performance, p is the probability that side effects will occur, and C is the severity of side effects (cf. [53], [56], [57]). Our first hypothesis states that an increase in expected utility from CE drug use increases the probability of CE drug use (H1). Second, when individuals internalize social norms that are contrary to CE medication use, the probability of using CE drugs decreases (H2). Third, the effects of internalized norms and expected utilities will interact in the following manner: When the norms are strongly internalized, the effect of utility on the probability of CE drug use will decrease (H3).