The Brain and Drug Addiction

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Neurobiological research is opening up our view of addiction as a disorder…

The Brain and Drug Addiction

(from Doctissimo website)

Why do some people become addicted to drugs when others can easily control their intake? What are the mechanisms that are involved in the brain? Are some of us more at risk than others?… Here a handful of experts give us some answers.


The progress made in the last few years in neurobiology has allowed a better understanding of drug addiction and has revealed that addiction is a real illness concerning the nervous system. For all this, however, society’s views have not changed and management of the problem remains inadequate.

What is addiction?

“Addiction is a functional disorder in the brain”, explains Dr. William Lowenstein, director of the Montevideo clinic in Boulogne-Billancourt which specialises in the management of addictions. In addition, for his colleague, Professor Pier Vincenzo Piazza, director of the Magendie Neurocentre in Bordeaux , “the main contribution made to neurobiology regarding drug addiction is that is has been shown to be a behavioural disorder”. Continuing, the neurobiologist complains that unfortunately “we are still stuck in the paradigm of 20 years ago according to which drug addiction is the fault of the addict”. He insists that “We should stop thinking of drug addiction as a vice when it is actually an illness.”

You hear of addictions to psychoactive substances or to behavioural activities (video-games, sex etc.) when the person affected is “compelled to continue using that substance or behave in that way in order to escape the feeling of need”, explains Professor Jean-Luc Venisse, head of the psychiatric department and addiction clinic at the Nantes University Hospital. “It is a downward spiral. Something switches in the brain”.

Addiction or excess?

  • Initial or later loss of control over consumption, leading to inability to resist temptation
  • Continuing with certain behaviour despite the knowledge of the damage it will cause and the negative consequences for that person’s social life, family and job
  • The notion of a “craving”; a term describing the temporary relief answering the tension prior to succumbing and connected to the feeling of need
  • A built up tolerance (this is after long term use and in large quantities in order to achieve the desired effect)
  • The appearance of withdrawal symptoms

Addiction: what is going on in the brain?

We know that many different regions of the brain are involved in addiction:

  • The prefrontal cortex, which plays a major role in decision-making and which constitutes a major relay in the reward circuit
  • The amygdala, which “connects emotions to our behaviour” and stores away memories of sources of pleasure and dislike
  • And probably also the insula, which could contributes to the conscious aspect of our desires and needs.

When the brain receives a reward it wasn’t expecting after a particular action, it “engraves” this positive outcome on the nervous system, encouraging repetition of the act. In an addict, the dopaminergic system can become overdeveloped, which means that the system no longer knows how to resist the consumption of a substance which procured it pleasure when it comes into contact with it again. This works in the same way for non-substance addictions.

At the Magendie Neurocentre, the teams of Professors Piazza and Olivier Manzoni have come up with evidence in rats of another possible cause of addiction, challenging what have been widespread conceptions until now. They showed that, in fact, “addiction stems more from a form of anaplasticity of the brain. This means that people dependent on a drug are unable to counteract the pathological modifications it causes in no matter who takes it”. To find out more, read our news story “Is drug addiction connected to a loss of elasticity in the brain?”


Are there any factors which can lead to addiction?

Many different factors are implicated in the development of a dependency: the neurobiological factors that have just been described as well as psychological factors and sociocultural (or environmental) influences. Addiction is actually very strongly tied to environment, to objects (slot machines, for example, have the potential to be very addictive) and to the individual. “We are not all the same when it comes to our abilities to regulate ourselves and to accept frustration, limitation and to postpone pleasure”, Professor Venisse points out.

For Dr. Vincent Bréjard, senior lecturer at the psychopathology clinic at the University of Aix-Marseille, the psychological factors must be taken into account. “According to this logic, addictive behaviour sets in through an attempt to resolve a psychological problem such as anxiety or depression”.

Anxiety plays an important role in the development of an addiction, with the person seeking to control the negative effects of his or her anxiety by resorting to illegal substances. This is also the case with “binge drinking” which is essentially a quest for an anaesthetising effect, using oblivion to escape anxious thoughts, as Professor Venisse explains. The role of depression in all this is more arguable, suggests Dr. Bréjard, for whom this psychological state “would be more of a secondary effect of the use of psychoactive products rather than the cause.”

Other factors contributing to psychological vulnerability named by the specialist include: low self-esteem, inability to appreciate feelings and get pleasure out of things (anhedonia), the search for strong sensations, novelty, or even difficulty building relationships with other people. “Certain people are unable to get beyond the dependency that a small child has on its parents, and this constitutes a basis for vulnerability to drug use and addiction.”

Addictions: what treatments are available?

Associated only with drugs for a long time, the definition of addiction has now been extended to cover any kind of habit where usage has become harmful, under a government scheme from 1999-2002. This view has allowed the ways in which addiction is managed to be opened up after being restricted to substances for a long time. Still, in the meantime, our increasingly individualistic society puts emphasis on immediacy, performance and short term concerns, and the treatment of those who are products of this is left wanting. For Professor Venisse, treatment of individuals with dependencies is still inadequate, not very effective and often too late. However, according to Dr. Lowenstein, “this illness is more easily reversible the better treatment it receives”. The old adage that says ‘once an addict, always an addict’ is complete rubbish!”, he fumes.

The problem is that there are too few treatments for addiction. “Few laboratories take on research in this because of the bad image of drug use which prevails. This is currently changing, even if laboratories do not work where work is needed but rather where the money is…” Professor Piazza says with regret. According to the specialists, the success rate of treatments ranges from 40% to 60% in a year, but with considerable variability from patient to patient. “The key element is support for the duration, as it is a chronic illness in which issues of relapse are of serious concern”, warns Dr. Lowenstein, citing cognitive and behavioural therapy where the objective is to modify the habits of an addict on a deep level.

Sources :

–    “Addictions and dependency”, press conference organised by the Federation for Research into the Brain (FRC), 8 December 2011.

–    When my brain became an addict… 5 questions/answers for a better understanding of addictions and treatment – 2012 Guide edited by the FRC.

“Transition to addiction is associated with persistent impairment in synaptic plasticity”, published in 2010 in the journal “Science” (an abstract is available on the Internet)


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