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Pleasure and pain
Pleasure-Seeking Behaviour
Avoiding Pain

Help Vulnerability to Addiction Everyone is Genetically Vulnerable to Addiction Sommes-nous tous des drogués ?
Undoing cocaine's consequences

About 60% of all Americans have tried illegal drugs. Even when you exclude marijuana, the figure is still close to 30%. And if you include alcohol, a substance that is legal but that can create a dependency, the figure rises to 90%. Very few of these people are actually going to develop a dependency. Even with a drug such as cocaine, which is highly conducive to dependencies, only 15 to 16% of the people who try it become dependent on it within the 10 years following the first time they take it.

It is interesting to compare the general attitude of one teenager who has low self-esteem and a fear of facing up to problems with another teen who is more confident and feels that he or she can cope with problems as they arise. These two teens will react very differently to the problems of everyday life. The psychologically healthy teen will try to take action to deal with them, while the teen whose behaviour is more inhibited will instead try to escape, often by using psychotropic drugs. Taking these drugs will temporarily suppress this teen’s sense of anguish, but increase his or her sense of failure at being unable to solve life’s problems.



The origins and causes of the various forms of drug addiction are still being debated within the scientific community. In some individuals, such as alcoholics, genetic predispositions may come into play.

But the consensus is that for most people, abusing psychoactive substances is a learned behaviour designed to cope with some form of distress. Some people use drugs to suppress disagreeable experiences (for example, drowning their sorrows in alcohol after a quarrel with a spouse). Others use drugs to enhance agreeable sensations (such as the feeling of disinhibition that drinking alcohol can bring).

Hence, it is the meanings that individuals ascribe to their behaviours that may pose a problem.It is the difference between the experience that an adult might have while sharing a joint in the evening with some friends, and the experience that a teenager might have while smoking the same amount of pot in secret to forget his or her problems.

Escalating consumption of a street drug or a medication is therefore the result of a process and attitudes that depend on factors in the particular individual’s personality, motivations, and life experience, as well as in his or her family setting and social environment. (To learn more about each set of factors, place your cursor over each part of the diagram below.)

The presence of a relatively large number of these contributing factors should set off an alarm about that individual’s risk of dependency on psychotropics.


Sommes-nous tous des drogués ? New advances in neuroscience are explaining why people just do it,exactly as they're told to, when that commercial comes on Incentive-sensitization and addiction Theories of Drug Addiction

The term ‘’sensitization’’ refers to an increase in the effect of a drug when it is used repeatedly. Sensitization is thus the opposite of tolerance. Sensitization may also occur because the underlying biological systems adapt in different ways to repeated exposure to a drug. The two kinds of drug effects that are generally subject to sensitization are psychomotor effects and reward effects. Since both types of effects involve the reward circuit, it is thought to be this neural system that undergoes the changes involved in sensitization.

The consumption of a drug is often associated with the consumption of other substances as well: alcohol with cigarettes, cannabis with tobacco, and ecstasy with certain psychoactive medications are common examples.

Someone may use several substances regularly (for instance, tobacco, alcohol and anxiolytics several times per week) or several substances all at once (for instance cannabis, alcohol, and tobacco all in the same evening).

Both types of behaviour are called “polyconsumption”. The effects of drugs can be amplified in such cases, leading to more serious health risks. Polyconsumption can also lead to polyaddiction, meaning dependency on several drugs.


Over the years, various theories have been offered as to how the changes in brain and behaviour associated with drug-taking can lead to dependency.

One of these theories is based on the traditional hedonist principle that people seek pleasure and avoid pain.

For proponents of this theory, dependency develops through positive reinforcement: people take drugs to try to repeat a pleasant experience. This theory was formulated in the mid-1980s on the basis of self-stimulation experiments conducted in the 1950s. But this view of drug addiction as a form of self-medication, in which individuals choose a given substance according to their particular needs and the particular effect they are seeking, has shown its limitations in other experiments over the years.

For other theorists, the main cause of drug addiction is the desire to alleviate the suffering that addicts experience when their drug is withdrawn. This theory of negative reinforcement was proposed as early as 1948. But it too fails to explain certain phenomena adequately, in particular the fact that drug addiction practically never develops when opiates are prescribed for somatic pain, if the prescription is written properly.

Solomon and Corbit’s opponent process theory (Solomon and Corbit 1973, Solomon 1977) offers an elegant explanation of drug addiction, combining the search for euphoria with the avoidance of withdrawal pain. Other authors have viewed drug dependency mainly as a learning aberration–specifically, the development of very strong habits of stimulus-response.

This theory is based on the discovery that the reward circuit appears to be involved in learning, and particularly in recording memories of the environmental markers associated with rewards. This explanation is helpful for understanding the effect of the environment on dependencies, but also has its limitations, with regard to both explicit and implicit learning.


Yet another approach begins with the observation that the mere presence of a reward, even one that is inaccessible, can cause the dopaminergic neurons in an animal’s brain to start secreting more dopamine. Simultaneously, the animal displays approach behaviour toward the reward in question. Some researchers believe these observations indicate that drug-seeking behaviour should be disassociated from the satisfaction that drugs provide. In this view, drug addicts have an exacerbated desire for their drug of choice, and the pleasure that it provides them becomes secondary. This theory even proposes that dopamine drives only the drug-seeking activity, while the experience of pleasure is triggered by other neural pathways.

In 1993, Robinson and Berridge suggested that a state of hyperexcitability (sensitization) of the mesolimbic dopaminergic system might be the source of the cravings that drug addicts experience. According to this theory, the dopaminergic system attributes a value, or “salience”, to stimuli associated with its activation, thus making them attractive or desirable “incentives”.

Still another theory holds that drug-dependent people suffer from a dysfunction of the systems of the frontal cortex that normally regulate decision-making and impose inhibitory controls on behaviour. This dysfunction would result in altered judgment and impulsiveness.

One last hypothesis focuses on the idea that individuals’ attitudes toward drugs depend fundamentally on whether the baseline activity of the dopaminergic neurons in their brains is above or below a certain level. If it is above this level, the individual experiences satisfaction. If it is below, the individual experiences a craving. There is an interesting analogy here with theories that individuals perceive and assess the intensity of pain by comparing it with subtler but related sensations experienced earlier.

The major drug-addiction-research institutes, such as the National Institute on Drug Abuse (NIDA) in the United States, regard drug addiction as a disease of the brain that may eventually be treated by various pharmacological methods. This approach is certainly more progressive than those that treat addicts as delinquents who must be punished.

But the phenomenon of drug addiction is far broader than its neurobiological corollaries alone. Even just to define it, its psychological and social dimensions must also be considered. For example, the problem with methadone treatments for heroin addicts lies not so much in the pharmacology of methadone as in the fact that patients perceive the system that provides these treatments as rigid, controlling, and oppressive. Drug addicts’ social isolation also makes it hard to reach them, earn their trust, and ultimately, offer them pharmacotherapy.

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