Substance abuse reward

Abused drugs generally produce pleasant effects that are desired by the user. However, while most individuals will experience these pleasant effects, not everyone abuses these drugs, and not everyone who abuses them becomes dependent on them. Why some persons abuse drugs while most people do not is a complex area of research. It appears that genetic, environmental, and cultural factors may all interact to predispose some individuals to substance abuse and subsequent dependence. The initial hedonic experiences secondary to use of drugs appear to be primarily due to their ability to activate the primary reward circuits in the brain. These same reward circuits operate under normal circumstances to reinforce certain activities that promote survival, such as food, social affiliation, or sexual activity. 

Reward Therapy. A similar (yet nonspecific) approach is to use a medication that stimulates the brain s reward centers. Reward medications usually do not work in quite the same way as the substance of abuse however, the net effect in the final common pathway (i.e., the reward centers) may be the same. For the most part, these reward centers are activated by either dopamine or endogenous opioid agonists. One common feature of most abused drugs is that they stimulate these reward centers. This lies at the heart of their addictive potential. Some attempts have been made to use medications that activate these reward centers in place of the abused substance. The hypothesis is that the addict will have less intense craving for his/her preferred substance of abuse in the presence of these other agents. This is, of course, a relatively nonspecific approach that could theoretically be used to treat the abuse of many different substances. It has not yet, however, demonstrated any utility in the treatment of substance abuse. 

Interference Therapy. This is conceptually the opposite of the replacement and reward therapies. Whereas replacement medications substitute for the abused drug by stimulating the same brain receptors, interference therapies block these receptors. When the substance abuser uses his/her drug of choice, its effects are blocked by the interference medication. As a result, the drug does not produce the same intensity of pleasurable effects. By reducing the pleasurable effects of drug use, the incentive for repeated use should decrease as well. 

Gardner, Eliot L. 1997. "Brain Reward Mechanisms." In Substance Abuse A Comprehensive Textbook, edited by Joyce H. Lowinson, Pedro Ruiz, Robert B. Mill-man, and JohnG. Langrod. Baltimore, Md. Williams and Wilkins. 

Brain Reward Mechanisms." In Substance Abuse A Comprehensive... 

Gardner, E. (1997), "Brain reward mechanisms," in J. H. Lowinson, et al. (eds.), Substance Abuse A Comprehensive Handbook, Baltimore Wiliams and Wilkins, pp. 51-65. 

Recoverythe process through which a substance abuser or addict learns to live within himself or herself, with other people, and with the world in a healthy and rewarding drug-free way. 

Benzodiazepine abuse is different from other substance abuse disorders (opiates, amphetamines, and nicotine) because benzodiazepines cause much less euphoria and do not activate the classic reward systems that are activated with other substances (mainly the mesolimbic and mesocortical dopaminergic projections). In fact, most people do not find the subjective effects of benzodiazepines pleasant beyond their therapeutic anxiolytic or sleep-inducing effects. Therefore, abuse of benzodiazepines is usually secondary to other substance-abuse disorders, with the benzodiazepine being taken for relief from symptoms induced by the use of another drug. As potential drugs of abuse, short-acting benzodiazepines seem to be preferred among addicts because of the rapidity of their onset of action (aiprazoiam, fiunitrazepam, and iorazepam). 

In the third case, in some jobs there is an immediate direct relatiorrship between effort and earnings from piecework payment, production bonuses, or sales commissions. And yet, for some people, immediate rewards for more work suit them for example, sales people in a sitrvey in Western Australian were shown to be a relatively healthy gronp. This is not necessarily a criticism of the varying approaches to work described here. Bnt it does emphasize the need for promotion of effective time management a balanced lifestyle with time for personal relationships and physical activity and careful monitoring of workers to ensure that overwork does not get to the point of reduced performance, ill health, poor interpersonal relationships, substance abuse or accidents. 

Explain the commonalities of action of abused substances on the reward system in the brain. 

Virtually all abused substances appear to activate the same brain reward pathway. 

While activation of the reward pathways explains the pleasurable sensations associated with acute substance use, chronic use of abused substances resulting in both addiction and withdrawal may be related to neuroadaptive effects occurring within the brain. 

O Virtually all abused substances appear to activate the same brain reward pathway. Key components of the reward pathway are the dopamine (DA) mesocorticolimbic system that projects from the ventral tegmental area (VTA) and the nucleus accumbens (NA) to the prefrontal cortex, the amygdala, and the olfactory tubercle (Figs. 33-3 and 33-4).5 Animal studies... 

FIGURE 33-4. Where different abused substances interact with the reward system in the brain. Data from reference 5. (From h ttp //www.drugabuse.gov/pubs/Teaching/)... 

Alterations in dopamine (DA) levels are associated with the rewarding effects of abused substances including cigarettes. Specifically, the mesolimbic DA pathway, which originates in the... 

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 typically self-administered via smoking tobacco, however, it is readily absorbed through the oral (chew) and nasal (snuff) mucosa. Among adolescents, nicotine is the most widely abused substance. Acute administration produces both stimulating and rewarding effects. Animal and some human studies have shown that nicotine improves both memory and attention. 

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