Addiction (Dopamine) Flashcards
The effect of addiction on the brain
In history, it would be hard to find a society either contemporary or historical that has not indulges in substances that can cause addiction
Each drug has a different effect upon people, and each interacts with different parts of the brain
All have some common characteristics - all achieve a pleasurable effect
Behaviour is learnt through reinforcement and conditioning
The brain strives to achieve balance, this balance can be disrupted by the effects of drugs and addictive behaviour
When we take drugs, the brain seeks to restore balance and adapts to the effect of the drug
Will involve the release of pleasure causing neurotransmitters on the brain, causes an imbalance with the brain seeks to counter
Mesolimbic pathway
Key brain area implicated in addiction is the mesolimbic pathway (reward pathway)
Created pleasurable feelings that reinforce the behaviour and make us want to do it again
Some rewarding behaviours (eating, drinking, sex) make biological sense to repeat
Not just rewarding the behaviours the activate this pathway, many drugs also cause these reward centres to activate, and create the feelings of pleasure that are rewarding and reinforcing
Dopamine levels are increases in participants given a gambling task and these levels raised regardless of whether the outcome was a win or not - Jousta et al (2012)
Alcohol increases dopamine levels in the brain - Boileau et al (2003)
Tolerance and withdrawal
If a drug is consumed regularly, it will alter the function of the brain, the brain will adapt to minimize the effect of the drug and restore normal function
If a drug is regularly used, the brain compensates and adapts to maintain the balance while the drug is present, when the drug is no longer taken, the brain becomes out of balance
It can take a long time of this neuroadaptation to adapt to the absence of the drug (withdrawal)
The unpleasant side effects often cause many people to start taking the drug again
When the drug is taken repeatedly, the effects of this drug will be diminished each time, a higher dose is needed in order to get the same effect (tolerance)
Tolerance actually works at the level of neurotransmitters is with the D2 receptors
Volkow et al (1997) found that in users of cocaine, there was a reduction in both the number of D2 receptors in the brain, as well as reduction in the release of dopamine
Low mood, irritable, sad
Olds and Milner (1954) placed an electrode in a region of a rat’s brain and stimulated it every time they went to a certain corner of the corner, researchers noticed that the rats kept returning to the same corner - pleasurable
Rats will press a lever to experience stimulation in this region of the brain
MAINTAINING ADDICTION: THE ROLE OF THE FRONTAL CORTEX
A simple pleasure response is not enough to explain all the characteristics of addiction
Proposed that the frontal cortex implicated in the maintenance of addiction
When the drug is no longer being taken, and the negative effects of withdrawal and tolerance have disappeared, many former addicts relapse and start using again
Frontal lobe is involved in higher order tasks, such as reasoning, planning of behaviour and memory
High levels of dopamine caused by addiction alter the functioning parts of the frontal cortex, changes that persist even when the drug is no longer being taken or the behaviour no longer engaging
Argued by Volkow that these changes to the frontal cortex can alter our attention, causing to pay more attention to stimuli associated with their addiction
Robinson and Berridge (2003) argue that this causes the addict to want to engage in the addictive behaviour, rather than just like it
Many addicts are compelled to engage in their addiction, even through they no longer gain any pleasure from it
Bolla et al (2003) saw impaired performances in tasks that would usually use the frontal cortex
Wang et al (1999) said that addicts show an increase in activity in their frontal cortex when exposed again to the drug on cues associated with them
Evaluation
An acknowledgement that addiction is beyond the control of the addict may mean that it is seen as a medical disorder or disease, and therefore will be treated as such
Legal system may refer drug users to treatment rather than prison
Not a sufficient explanation of all addiction
Stokes et al (2009) found no significant increase in dopamine levels in volunteers taking cannabis
Yoder et al (2007) found no consistent increase in dopamine across the participants in their study who were given alcohol
Dopamine does not just perform one function, it does many things in many different parts of the brain
Uses animals in studies
Most experiments done in a laboratory setting
Very reductionist
Factors being ignored
Unclear how well it can explain behavioural addiction
Ignores individual differences
Differences within individuals in the functioning of their mesolimbic pathway before the addictive behaviour is engaged
Does not explain what causes the person to engage in the addictive behaviour in the first place
Ethical issues
If addicts believe their behavior is beyond their control, they may feel powerless to change it
May be a gender / culture bias
