Müller & Schumann (M&S) stress the importance of a more detailed conceptualization and study of the reasons behind drug taking, along with the notion that it can often be associated with benefits to the individual. The conceptualization and model formulization describing drug instrumentalization fills the gap left by the majority of prevailing theories of drug use that focus on drug abuse and addiction without specifically addressing the initiation of drug use and offer no account of stable, non-abusing drug intake patterns. One element that requires more consideration is the efficiency and accuracy of the employment of drug instruments to achieve specific changes in mental state, along with how a lack of precision may affect long-term patterns of drug taking.
Although it is clear that individuals take drugs to achieve a variety of goals, it is unclear how optimally an individual is able to achieve instrumentalization of a drug (i.e., desired vs. unwanted consequences of intoxication) and how these abilities may vary between substances and between individuals. In general, achieving a specific mental state will require ingestion of drug in a specific range; and variation from this range, in particular higher dosing, is likely to result in additional, potentially aversive, effects of the drug. As such drug use, with or without dependence, may involve non-optimal instrumentalization or a degree of “mis-instrumentalizaiton” (i.e., the ingestion of a pharmacological substance that fails to appropriately achieve the desired purpose determined in the drug-free state); and the deviation from the desired endpoint may be an important construct in determining the net beneficial and detrimental consequences. Given the delayed onset and enduring nature of drug effects following ingestion, it is also likely that mis-instrumentalization would tend to result from excess drug intake, a condition known to promote neuroadaptations and facilitate the addiction process (e.g., Koob et al. Reference Koob, Ahmed, Boutrel, Chen, Kenny, Markou, O'Dell, Parsons and Sanna2004). Below, I provide a non-exhaustive summary of drug characteristics and individual factors that will contribute to mis-instrumentalization of drugs.
Abuse liability of a specific drug is a widely employed concept in addiction research, and a reconceptualization in relation to the utility of drugs may be informative. Specifically, the impact of drug instruments on specific psychological processes may reveal which drugs are likely to be misused or “mis-instrumentalized,” resulting in an increased likelihood that the individual will encounter problems when using the drugs regardless of intended purpose. Drugs that produce high levels of euphoria are likely to be abused even when initially taken for a medical purpose, which reduces the overall therapeutic utility of such drugs. Drugs that produce cognitive deficits, particularly those inducing deficits in judgment, as well as in timing and working memory (faculties that are necessary to gauge ongoing dosing), would probably produce mis-instrumentalization through either poor decisions on continuing drug intake or failure to accurately gauge cumulative intake. Further, a variety of drugs impair inhibitory control processes; and as M&S argue, such impairment may be the exact effect desired for instrumentalization (e.g., alcohol for social disinhibition). However, impairing behavioral control would also disrupt the ability to maintain intake in the desired range. Together these factors are likely to link abuse/addiction liability to the probability for mis-instrumentalization.
On the other hand, the optimal instrumentalization of drugs would be expected to vary across individuals and time. First, the ability to instrumentalize a drug for a specific effect requires intake that achieves specific dose ranges of intoxication with deviation from these levels resulting in overintoxication, adverse side effects, or both. This ability to instrumentalize drugs should not be viewed as innate but, rather like other operant behaviors, the relation between intake and achieving a desired mental state that must be learned. Inexperienced users are highly likely to fail to appropriately gauge intake for desired effect; and given that most drugs are both powerful biological instruments and promoters of adaptive processes, the acquisition of drug instrumentalization may result in high levels of abuse as well as promoting addiction. Second, responsiveness to drugs differs enormously between individuals. Individual variability is exhibited across almost all aspects of drug responsiveness and forms of learning and, hence, the ability to appropriately instrumentalize drugs for specific effects most likely varies between individuals. Conceivably, poor “learners” will fail to appropriately regulate intake to achieve the desired state and avoid excess intake. Individuals responding in such a fashion are at risk for repeatedly abusing drugs and are likely transitioning into addictive behavior. Third, responsiveness to drugs also differs within an individual across time. For example, it is widely reported that the subjective effects of psychostimulant drugs vary across women's reproductive cycles (Evans & Foltin Reference Evans and Foltin2010). Hence, if women, relative to men, attempt to instrumentalize cocaine intake for a desired level of euphoria, they would be expected to make more errors in determining the desired level of drug intake (i.e., more likely to take excessive amounts of drug), which could mediate sex differences in addiction vulnerability (Becker & Hu Reference Becker and Hu2008). Analogous elevations in the potential for misinstrumentalization would be expected for changes in stress levels, energetic states, age, and so forth. Accordingly, it may be that an inability, whether enduring or transient, to appropriately gauge necessary levels of drug intake for drug instrumentalization would put an individual at risk for aversive consequences, including induction of neuroadaptations mediating the development of addictive behaviors.
Further, in addition to the proximate mechanism that M&S discuss, drugs are used to “fit in” or to indicate maturity. The impacts of “peer pressure” and mimicry of parents/role models on drug taking should not be overlooked as these factors are likely to contribute to the motivation to use a drug, as well as the desired drug effect to be achieved. Accordingly, the role of semantic knowledge of or perceived knowledge of drug use by others, as well as the social context of that semantic knowledge, may explain the high impact of environment on early drug use (e.g., Kendler et al. Reference Kendler, Schmitt, Aggen and Prescott2008), a time when the user is relatively inexperienced with the drug and the pathways to beneficial drug use or detrimental drug abuse are largely undetermined.
Müller & Schumann (M&S) stress the importance of a more detailed conceptualization and study of the reasons behind drug taking, along with the notion that it can often be associated with benefits to the individual. The conceptualization and model formulization describing drug instrumentalization fills the gap left by the majority of prevailing theories of drug use that focus on drug abuse and addiction without specifically addressing the initiation of drug use and offer no account of stable, non-abusing drug intake patterns. One element that requires more consideration is the efficiency and accuracy of the employment of drug instruments to achieve specific changes in mental state, along with how a lack of precision may affect long-term patterns of drug taking.
Although it is clear that individuals take drugs to achieve a variety of goals, it is unclear how optimally an individual is able to achieve instrumentalization of a drug (i.e., desired vs. unwanted consequences of intoxication) and how these abilities may vary between substances and between individuals. In general, achieving a specific mental state will require ingestion of drug in a specific range; and variation from this range, in particular higher dosing, is likely to result in additional, potentially aversive, effects of the drug. As such drug use, with or without dependence, may involve non-optimal instrumentalization or a degree of “mis-instrumentalizaiton” (i.e., the ingestion of a pharmacological substance that fails to appropriately achieve the desired purpose determined in the drug-free state); and the deviation from the desired endpoint may be an important construct in determining the net beneficial and detrimental consequences. Given the delayed onset and enduring nature of drug effects following ingestion, it is also likely that mis-instrumentalization would tend to result from excess drug intake, a condition known to promote neuroadaptations and facilitate the addiction process (e.g., Koob et al. Reference Koob, Ahmed, Boutrel, Chen, Kenny, Markou, O'Dell, Parsons and Sanna2004). Below, I provide a non-exhaustive summary of drug characteristics and individual factors that will contribute to mis-instrumentalization of drugs.
Abuse liability of a specific drug is a widely employed concept in addiction research, and a reconceptualization in relation to the utility of drugs may be informative. Specifically, the impact of drug instruments on specific psychological processes may reveal which drugs are likely to be misused or “mis-instrumentalized,” resulting in an increased likelihood that the individual will encounter problems when using the drugs regardless of intended purpose. Drugs that produce high levels of euphoria are likely to be abused even when initially taken for a medical purpose, which reduces the overall therapeutic utility of such drugs. Drugs that produce cognitive deficits, particularly those inducing deficits in judgment, as well as in timing and working memory (faculties that are necessary to gauge ongoing dosing), would probably produce mis-instrumentalization through either poor decisions on continuing drug intake or failure to accurately gauge cumulative intake. Further, a variety of drugs impair inhibitory control processes; and as M&S argue, such impairment may be the exact effect desired for instrumentalization (e.g., alcohol for social disinhibition). However, impairing behavioral control would also disrupt the ability to maintain intake in the desired range. Together these factors are likely to link abuse/addiction liability to the probability for mis-instrumentalization.
On the other hand, the optimal instrumentalization of drugs would be expected to vary across individuals and time. First, the ability to instrumentalize a drug for a specific effect requires intake that achieves specific dose ranges of intoxication with deviation from these levels resulting in overintoxication, adverse side effects, or both. This ability to instrumentalize drugs should not be viewed as innate but, rather like other operant behaviors, the relation between intake and achieving a desired mental state that must be learned. Inexperienced users are highly likely to fail to appropriately gauge intake for desired effect; and given that most drugs are both powerful biological instruments and promoters of adaptive processes, the acquisition of drug instrumentalization may result in high levels of abuse as well as promoting addiction. Second, responsiveness to drugs differs enormously between individuals. Individual variability is exhibited across almost all aspects of drug responsiveness and forms of learning and, hence, the ability to appropriately instrumentalize drugs for specific effects most likely varies between individuals. Conceivably, poor “learners” will fail to appropriately regulate intake to achieve the desired state and avoid excess intake. Individuals responding in such a fashion are at risk for repeatedly abusing drugs and are likely transitioning into addictive behavior. Third, responsiveness to drugs also differs within an individual across time. For example, it is widely reported that the subjective effects of psychostimulant drugs vary across women's reproductive cycles (Evans & Foltin Reference Evans and Foltin2010). Hence, if women, relative to men, attempt to instrumentalize cocaine intake for a desired level of euphoria, they would be expected to make more errors in determining the desired level of drug intake (i.e., more likely to take excessive amounts of drug), which could mediate sex differences in addiction vulnerability (Becker & Hu Reference Becker and Hu2008). Analogous elevations in the potential for misinstrumentalization would be expected for changes in stress levels, energetic states, age, and so forth. Accordingly, it may be that an inability, whether enduring or transient, to appropriately gauge necessary levels of drug intake for drug instrumentalization would put an individual at risk for aversive consequences, including induction of neuroadaptations mediating the development of addictive behaviors.
Further, in addition to the proximate mechanism that M&S discuss, drugs are used to “fit in” or to indicate maturity. The impacts of “peer pressure” and mimicry of parents/role models on drug taking should not be overlooked as these factors are likely to contribute to the motivation to use a drug, as well as the desired drug effect to be achieved. Accordingly, the role of semantic knowledge of or perceived knowledge of drug use by others, as well as the social context of that semantic knowledge, may explain the high impact of environment on early drug use (e.g., Kendler et al. Reference Kendler, Schmitt, Aggen and Prescott2008), a time when the user is relatively inexperienced with the drug and the pathways to beneficial drug use or detrimental drug abuse are largely undetermined.