The following source offered some valuable information about four different theoretical explanations of addiction:
Robinson, Terry E., and Berridge, Kent C.
"Addiction." Annual Review Psychology 2003. 54:25–53. N.p., 14 Aug.
2002. Web. 2 Mar. 2014.
I read through the whole article, copying and pasting pertinent excerpts from the article below. Having the highlights from the article pulled out for me will help me to use this source more effectively when writing my paper.
"The development of addiction involves a transition from casual to compulsive patterns of drug use. This transition to addiction is accompanied by many drug-induced changes in the brain and associated changes in psychological functions. In this article we present a critical analysis of the major theoretical explanations of how drug-induced alterations in psychological function might cause a transition to addiction. These include: (a) the traditional hedonic view that drug pleasure and subsequent unpleasant withdrawal symptoms are the chief causes of addiction; (b) the view that addiction is due to aberrant learning, especially the development of strong stimulus-response habits; (c) our incentive-sensitization view, which suggests that sensitization of a neural system that attributes incentive salience causes compulsive motivation or “wanting” to take addictive drugs; and (d) the idea that dysfunction of frontal cortical systems, which normally regulate decision making and inhibitory control over behavior, leads to impaired judgment and impulsivity in addicts."
"Substantial numbers of people do become addicts, of course, but the fact remains that drug use does not inevitably lead to addiction. Addiction is more than mere drug use. It is defined specifically as a compulsive pattern of drug-seeking and drug-taking behavior that takes place at the expense of most other activities. The key questions in addiction, therefore, are why do some susceptible individuals undergo a transition from casual drug use to compulsive patterns of drug use, and why do addicts find it so difficult to stop using drugs"
"However, addictive drugs not only engage these brain reward systems, often more potently than natural rewards, but they can also change them."
The first cause this article discusses is:
"The most intuitive explanation for addiction is the traditional view that drugs are taken first because they are pleasant, but with repeated drug use homeostatic neuroadaptations lead to tolerance and dependence, such that unpleasant withdrawal symptoms ensue upon the cessation of use. Compulsive drug taking is maintained, by this view, to avoid unpleasant withdrawal symptoms. This two-sided hedonic hypothesis has gone by many different names: pleasure-pain, positive-negative reinforcement, opponent processes, hedonic homeostasis, hedonic dysregulation, reward allostasis, etc.No matter what the name, these hypotheses posit the same basic explanatory logic: Addictive drugs are taken initially simply to achieve pleasant drug “highs,” and after addiction, to escape withdrawal 'lows'."
"Everyone agrees that addicts sometimes take drugs chiefly for pleasure and sometimes chiefly to escape withdrawal or other dysphoric states (e.g., life stresses). However, there are several major problems with hedonic/withdrawal theories as full explanations of drug addiction. One of the most striking is that drug withdrawal actually may be much less powerful at motivating drug-taking behavior than people generally think. Relative to positive incentive processes caused directly by drugs themselves, or stress, withdrawal states are not especially potent in motivating drug-seeking behavior."
"Another major problem for withdrawal theories is explaining why addicts so often relapse into drug-taking again even after they are free from withdrawal."
The second cause this article discusses is:
"drugs produce abnormally strong or aberrant associations involved in reward learning, more powerful than natural reward associations"
"Abnormally strong explicit learning might distort declarative memories or expectations in two ways. (a) Conscious memories of the hedonic drug experience might be especially vivid and/or abnormally intrusive. (b) Drugs could exaggerate or distort declarative memories such that memory-based cognitive expectations about drugs become excessively optimistic. Such memories or expectations would be both false and dangerous because they make inaccurate predictions about the consequences of taking drugs."
"the fundamental problem in addiction is that cognitively accessible memories of drug pleasure are exaggerated or otherwise altered. That idea seems strained when compared with what addicts typically say about their lives. Most addicts do not seem to have rose-colored delusions of reward implied by a hypothesis of exaggerated declarative memories or expectations of drug pleasure. Instead, they accurately predict drug pleasure and often agree their drug use is not justified by the pleasure they get."
"Tiffany (1990)that “with sufficient practice, performance on any task … can become automatic … ” and “drug-use behavior in the addict represent one such activity, controlled largely by automatic processes” (p. 152). So how do these hypotheses explain addiction? Basically they suggest that over-learned habits become so automatic that they essentially become compulsive."
" However, habits are not intrinsically compulsive in any motivational sense, no matter how automatic they are. For example, tying your shoe, brushing your teeth, and many other habits in daily life are highly automatic and may be executed without need of cognitive attention. However, none of these behaviors are performed compulsively (except perhaps in obsessive-compulsive disorder, which requires a separate explanation). You probably have no overwhelming motivational urgency to tie your shoe, and you can stop brushing your teeth midway without distress at leaving the habit unfinished. You would not sacrifice your home, your job, your friends, and all that is dear in your life to engage in a shoe-tying habit, even though it is strongly learned and quite automatic. Its practiced automaticity does not compel you to perform it."
"An addict who steals, another who scams, another who has the money and simply must negotiate a drug purchase—all face new and unique challenges with each new victim or negotiation. Instrumental ingenuity and variation are central to addictive drug pursuit in real life. When an addict's drug-taking ritual is interrupted, for example, by lack of available drugs, flexible and compulsive pursuit is brought to the fore. The strongest S-R habit in the world does not explain the frantic behavior that ensues. Thus, the formation of S-R habits may explain the rituals addicts display in consuming drugs, but they do not account for the flexible and deliberate behaviors involved in obtaining drugs. We believe the flexible and compulsive nature of drug-seeking behavior in the addict requires an additional motivational explanation, separate from habit learning"
"we suggest the transition to addiction may not be reducible to aberrant learning per se, just as it is not reducible to withdrawal. Knowledge, in any implicit or explicit form of association, no matter how strong, does not necessarily compel the pursuit of drugs. The critical question is, what goads addicts to action? We believe the answer lies in understanding how learning and incentive-motivational processes are joined in the transition to addiction."
The third cause this article discusses is:
"addictive drugs enduringly alter NAcc-related brain systems that mediate a basic incentive-motivational function, the attribution of incentive salience. As a consequence, these neural circuits may become enduringly hypersensitive (or “sensitized”) to specific drug effects and to drug-associated stimuli (via activation by S-S associations). The drug-induced brain change is called neural sensitization. We proposed that this leads psychologically to excessive attribution of incentive salience to drug-related representations, causing pathological “wanting” to take drugs."
"The activation of a sensitized system that attributes incentive salience to drug-associated stimuli and their representations can sometimes be manifest implicitly in drug-seeking behavior. If the “wanting” system is activated implicitly it can instigate and guide behavior without a person necessarily having conscious emotion, desire, or a declarative goal. For example, in normal people the brief subliminal presentation of faces expressing positive emotions (backward masked and so brief they do not cause any conscious feeling of emotion at the time they are presented) can activate implicit “wanting,” increasing subsequent consumption of a beverage. In addicts, doses of drugs that are too low to produce any conscious experience of pleasure can activate implicit “wanting,” as indicated by an increase in drug-seeking behavior. Implicit “wanting” is similar to implicit memory and to unconscious perception (e.g., blindsight), which can occur and influence behavior without conscious awareness. At other times incentive-sensitization can be manifest explicitly, when cognitive elaboration translates incentive salience attributions into the level of conscious awareness of the corresponding representations. In those cases, the initial activation of an implicit “wanting” system contributes to the explicit subjective experience of a conscious desire for drugs, in the ordinary sense of wanting. Finally, the sensitized neural systems responsible for excessive incentive salience can be dissociated from neural systems that mediate the hedonic effects of drugs, how much they are “liked.” In other words, “wanting” is not “liking.”
"Another important feature of sensitization for addiction concerns individual differences in susceptibility to sensitization. Some individuals sensitize readily, whereas others are more resistant. That may help explain why only some drug users become addicts. Susceptibility to sensitization is determined by a host of factors, including genes, sex hormones, stress hormones, past trauma, etc., in addition to individualized patterns of drug exposure. Further, once sensitized, most individuals show cross-sensitization, which means that sensitization to one drug can cause sensitized effects for other drugs as well. Even more intriguing, cross-sensitization can occur between drugs and nondrug stress. Animals previously exposed to stress may become sensitized to some potentially addictive drugs. Conversely, animals sensitized by drugs may become hypersensitive to stress. Stress-drug cross-sensitization might be especially important in influencing stress-precipitated relapse, as well as initial susceptibility to addiction"
"Although many questions concerning causal relationships remain to be addressed, it is now well accepted that sensitization is accompanied by a major reorganization of brain reward systems "
"We hypothesize that it is specifically sensitization of incentive salience attribution to representations of drug cues and drug-taking that causes the compulsive pursuit of drugs and persisting vulnerability to relapse in addiction. Incentive salience attribution is hypothesized to transform the neural representations of otherwise neutral stimuli into salient incentives, able to “grab” attention, and makes them attractive and “wanted.” Individuals are guided to incentive stimuli by the influence of Pavlovian stimulus-stimulus (S-S) associations on motivational systems, which is psychologically separable from the symbolic cognitive systems that mediate conscious desire, declarative expectancies of reward, and act-outcome representations "
"relapse in human addicts after attempts to quit might also be caused by persisting sensitization in brain systems that mediate incentive salience. Upon encountering drug cues, the addict might suddenly “want” to take drugs again—to an excessive and compulsive degree—regardless of cognitive expectancies about “liking,” declarative goals, absence of withdrawal, etc."
"relapse in human addicts after attempts to quit might also be caused by persisting sensitization in brain systems that mediate incentive salience. Upon encountering drug cues, the addict might suddenly “want” to take drugs again—to an excessive and compulsive degree—regardless of cognitive expectancies about “liking,” declarative goals, absence of withdrawal, etc."
The fourth cause this article discusses is:
"The irrationality of the sensitized pursuit of drugs arises from several features of incentive sensitization. For example, even if a person knows cognitively that the drug will not give much pleasure (e.g., if the dose is low or quality is poor), sensitized implicit “wanting” can overcome low expectations of “liking.” The distinction between “wanting” and “liking” can sometimes result in strange dissociations in addicts, in which goal-directed drug-seeking behavior occurs in the absence of conscious awareness that pursuit is underway, and is dissociated from the ability of drugs to produce pleasure; that is, addicts will pursue drugs they do not like, as well as those they like. Second, irrationality could arise from the temporary reversibility of cue-triggered “wanting,” which momentarily overrides more rational and stable life priorities. Even if a person's explicit declarative goal is abstinence, implicit incentive salience attributions can undermine these explicit goals. And even if a person has a stable rational resolution to abstain from taking drugs, an encounter with drug cues may trigger “wanting” that competes with, and may momentarily surpass, rational intentions, precipitating a binge of relapse."
"Thus, drug-induced impairments in frontocortical function may contribute in important ways to the suboptimal choices and decisions addicts make concerning drug use. In addition, decreased activity in the prefrontal cortex may increase activity in subcortical dopamine systems. This raises the interesting possibility that frontocortical dysfunction may not only lead to poor decision-making and judgment, but it could further exacerbate incentive-sensitization. A loss of inhibitory control over behavior and poor judgment, combined with sensitization of addicts' motivational impulses to obtain and take drugs, makes for a potentially disastrous combination."
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