Addictive substances

Toluene, volatile nitrites, and anesthetics, like other substances of abuse such as cocaine, nicotine, and heroin, are characterized by rapid absorption, rapid entry into the brain, high bioavailability, a short half-life, and a rapid rate of metabolism and clearance (Gerasimov et al. 2002 Pontieri et al. 1996, 1998). Because these pharmacokinetic parameters are associated with the ability of addictive substances to induce positive reinforcing effects, it appears that the pharmacokinetic features of inhalants contribute to their high abuse liability among susceptible individuals. 

Given the low incidence of severe withdrawal symptoms and the modest effects on the mesolimbic dopamine (reward) system, most investigators have found that cannabis has a low abuse or addiction potential. However, it has been argued that if cannabis is a non-addictive substance, why is its use so widespread and why are there so many longterm and heavy users Finally, contrary to the evidence that cannabis can produce chronic tolerance, some regular users report that they require less drug to achieve the same high, or sensitisation (Chapter 3). Three possible explanations may account for this. First, chronic users may focus on the effects that they wish to achieve. Second, the... 

Nicotine is an addictive substance with rewarding and reinforcing properties. On the other hand, the autonomic responses following an acute nicotine treatment and the bitter taste of nicotine may cause aversion. This aversion may impact conditioned effects to nicotme. Rinker et al. (2008) studied possible sex differences in taste aversion mduced by nicotine in rats systemic nicotine or saline injections were paired wim oral saccharine. Although nicotme did produce a weak taste aversion, no sex differences were observed, excluding the possible contribution of the aversive properties of nicotine on sexually dimorphic responses to nicotine. The authors conclude that sex differences may arise from differences in the rewardmg properties of the drug. 

Nicotine is a plant product, particularly abundant in tobacco. Plant products containing ring structures and at least one nitrogen atom are known as alkaloids. Nicotine is one of the most addictive substances known ask any cigarette smoker who has tried to quit. 

Within this Held, most of the research and results have been focused on the effects of drug therapy on the disorders induced by alcohol, and by the abuse of opiates. For a broader discussion of substance abuse see Chapter 18. In all instances of alcohol or drug abuse the first objective is to wean the patients from the addictive substance, treating or preventing the effects of withdrawal for those substances which cause physical dependence (alcohol, nicotine, opiates, caffeine, certain psychotropic agents such as benzodiazepines, possibly antidepressants). The second phase is the prevention of recurrence or relapse, which relies on a combination of social support, psychotherapy, and pharmacotherapy where available. In this respect, alcoholism is exemplary. 

Let me press this point a bit further. I am told that it is possible for a well-supplied heroin addict to live an otherwise healthy and productive life. (It appears to be otherwise with cocaine and amphetamines.) In any case, imagine that this is so for a certain severely addictive substance,, and that in a certain culture, otherwise similar to ours, the use of S is not only tolerated but respected as highly spiritually beneficial. This culture regards the dependency on this substance, which is to say, the vulnerability to various kinds of diminished self-control, as a small price to pay for the enrichment of human life provided by S. Fortunately, S is easily obtainable, perhaps even subsidized by the society for religious reasons. 

I am not arguing that addictions of any kind should be valued in the way we value the attachments just mentioned. Perhaps we are right as a culture to disrespect addiction. That deserves a separate discussion. My point is that these forms of dependency cannot be disparaged solely on the grounds that they diminish self-control, that is, simply because they are dependencies. Addictions must be shown in some further way to reduce the value of human experience or agency. Obviously, countless lives have been ruined by devotion to drugs. On the other hand, addictive substances help many of us to endure what would otherwise be rather bleak prospects. 

It is important to distinguish the effects on rationality of the dependency itself from the more direct effects of the ingestion of certain addictive substances. As dependencies, all addictions create liabilities to irrationalities when one is deprived (or threatened with deprivation) of the substance. Addictive substances differ, however, in their intoxicating properties. Being "high" may itself diminish rationality. I suspect these differences are linked to the different capacities of substances to lead to what I call existential dependency some of these impairments of consciousness are precisely what one comes to "need." ( , 1 am indebted to discussion with Susan Neiman.)... 

My own research group has reported that the brain rewardenhancing property of -tetrahydrocannabinol, the addictive substance in marijuana and hashish, is much more pronounced in Lewis rats than in other strains, as measured both by direct electrical brain stimulation reward and by in-vivo brain microdialysis of synaptic DA overflow in... 

The fundamental axiom in Ainslie s theory is motivational inconsistency and ambivalence, and the theory describes the strategies people may use to handle the resulting problems. The theory therefore allows for more complex interactions between conflicting motives within the person than do the conventional utility calculus that Becker and Murphy apply. However, as opposed to Becker and Murphy, Ainslie does not base his addiction theory on any explicit assumptions about the properties of potentially addictive substances. The phenomena Ainslie describes in his addiction theory are quite general and not restricted to the addictions. Since potentially addictive substances clearly do have specific properties that other substances do not have, it would be of interest to apply Ainslie s scheme to a consumption good with such properties. 

In effect, hyperbolic discounters with only a little amount of willpower (N < 11) will not be able to quit their addiction, and if they have been abstaining for a while, they will quickly relapse to addiction. Hence, unless they are able to cultivate their willpower, they will continue their self-destructive lifestyle. These people are consonant addicts (Skog 1999) They are unable to quit and really do not wish to quit, as they consider life without the addictive substance to be even worse than life as a heavy consumer. 

Again, not all the putative addictions have all the phenomenological features. Whereas craving and cue dependence seem to be universal features of any candidate member of the group of addictive substances or... 

Beliefs provide a final source of variation in the consumption of addictive substances. Many social norms are intertwined with beliefs about the effects of consumption. Again, alcohol provides a privileged example, although I also refer to other addictive substances. 

In an influential article, Gary Becker and Kevin Murphy (1988) present a model of rational addiction. The model has two main aspects. On the one hand, it offers a simple causal model of the consequences of consuming addictive substances. On the other hand, it offers a standard belief-desire account of how people might choose to engage in such consumption. 

Physical dependence A phenomenon that develops during prolonged use of addictive substances, signified by the onset of withdrawal symptoms when the drug is discontinued. 

Remember that caffeine interferes with sleep when consumed past midafternoon. It is also an addictive substance that tricks you into feeling more alert. If you feel you need coffee, maybe what you need is more rest. 

Summary Provides detailed information about the composition, history, effect, uses and abuses of common drugs, including illegal drugs and addictive substances, as well as commonly abused classes of prescription drugs. 

Legally, caffeine is not regulated as a dangerously addictive substance. Yet, withdrawal from caffeine is documented as a recognized set of symptoms in the medical literature. Many people who regularly consume caffeine and then suddenly stop will experience... 

The World Health Organization classified dextromethorphan as a non-analgesic, non-addictive substance in the late 1960s. In 1970, the Controlled Substance Act further added weight to this notion that dextromethorphan is not in the same class of drugs as its opiate forbearers in its abuse potential. This led to the decision of the DEA to leave dextromethorphan off its schedules of controlled substances. 

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