reward and addiction in the brain Flashcards
what 3 components compromised dependency syndrome(addiction)?
-tolerance
-dependence
-withdrawal
what are the 3 reward circuitry links in dopaminergic pathways linking?
1.ventral tegmental area
2.nucleus accumbens
3.cortical and limbic areas
what is dependency syndrome described as ?
relapsing-remitting disorder
what is relapsing-remitting disorder?
comprising behaviours that are performed in a compulsive manner, in spite of the potential for self-harm
Dependence
reliance on a substance or behaviour and many think that this is synonymous with addiction
what can 2 things can dependence be categorised by?
1.psychological dependence
2.physical dependence
tolerance(basic chemical approach)
describes the requirement for increasing amount of drug/behaviour to elicit the same level of positive reinforcement (‘high’) as that experience during previousexposures to the substance/behaviour
what happens during tolerance , the first time someone takes a drug?
1.firstly theres a positive effect of the drug when you take it the first time
2.then it will go down -where there could be a little negative effect as an individual comes of the drug
3.then it goes back to normal
what 3 forms does tolerance take?
1.acute
2.chronic
3.learned
Acute(or short-term
tolerance is usually caused by repeated exposure to a drug over a relatively short period of time, e.g. repeatedly using cocaine over a single night results in a rapid decrease in the ‘highs’ perceived
Chronic (or long-term
tolerance develops as a result of constant exposure to a substance over a prolonged period of time, e.g. prescription opioid use that over weeks or months can lead to increasing doses needed
Learned
results from frequent exposure to substances that become integrated into the normal behavioural routines, e.g. some people who abuse alcohol often seem unaffected by the substance (the so-called ‘high-functioning’ people in lay terms), learning to compensate for the effects of alcohol over time.
Withdrawal
describes the effects of removal of subject of dependence. It is different from the rebound dip in mood/behaviour often called the ‘crash’ that occurs immediately followingwear-off of the positive effects of the drug/behaviour
2 types of withdrawal linked to dependence?
1.physical
2.psychological
Drug-seeking/Craving behaviours
the anticipation of obtaining/taking a drug prior to its use.
Binging/intoxication behaviours
broadly covers taking the substance, the ‘highs’ and also includes issues of tolerance and dependence
Withdrawal behaviours
negative effects of removal of the dependent substance.
how does dependency develop ?
Intoxication activates the reward pathways:
Nucleus accumbens/ventral striatum
what are the activation of cognitive and emotional circuits of the forebrain?
pleasure centres
binge circuitry
-basal ganglia(striatum and globus pallidus
-thalamus
what does withdrawal lead to ?
Rapid decrease in mood and increase of negative effects - even though the plasma concentration relatively high.
what are negative effects of withdrawal
Preoccupation/anticipation
Activation of association areas lead to ‘remembering’ that the bad feeling are reversed by doing the behaviour.
how does the cycle of dependency work?
repeating cycles of binge-withdrawal-craving associated with misuse of substances forms the basis of habit formation
in the cycle of dependency what does plasticity alter?
neuronal composition at all levels of the system
what 3 ways do changes in levels during cycle of dependency occur?
1.epigenetic
2.cellular
3.structural
opioid receptors
shown to alter as a result of dependency, with more κ (kappa) receptors being made (associated with more psychological effects) compared to μ (mu) receptors.
are addictive behaviours heritable ?
Most addictive behaviours are moderately to highly heritable
what inheritance is dependency most likely through?
polygenic inheritance
what does it mean when behaviours can be readily activated on relapse?
Most addictive behaviours are moderately to highly heritable
what does the transtheoretical modal-stages of change describe ?
the processes that individuals go through whilst attempting to alter their behaviour. It is used as a framework to aid development of appropriate support mechanisms to enable achievement of the individuals goals.
what 5 stages does the transtheoretical modal have?
1.Pre-contemplation
2.Contemplation
3.Preparation
4.Action
5.Maintenance
what is the precontemplation stage include?
no recognition of need for or interest in change
what is the contemplation stage ?
thinking about changing
what is the action stage ?
adopting new habits
what is the maintenance stage?
ongoing to practice of new, healthier behaviour
what 3 approaches are used to reduce usage and harm for substances of misuse?
1.Detoxification (withdrawal)
2.Substitution
3.Harm-reduction
what is detoxification(withdrawal), substitution and harm-reduction ?
aimed at changing behaviour patterns which reduce usage and impact of using on health
Opioid dependency management- what is pharmacological intervention in help?
helping patients move away from dependency
what opioids are useful in substitution therapy?
1.Beuperenorphine
2.methadone
what antagonist can reduce relapse?
naltrexone
Many mechanisms are employed to help improve compliance ?
1.Random urinalysis
2.Daily pick-up/Instalment prescriptions
3.Titrate doses against symptoms
4.Psychosocial support
Reward
feeling (high) experienced after performing a specific behaviour
Positive reinforcement
makes it more likely to be repeated and become a habit
what happens in the tolerance stage when the individual repeatedly takes the drug?
1.the positive effect drops of overtime with repeated use
2. negative effects tend to get bigger
detox
controlled withdrawal from a dependency
why is there a crash after the high of taking a drug?
there are changes in the region of the brain that are controlling these types of behaviours
-this is due to neural circuitry which is underpinning these behaviours -this is the interplay between pre-frontal cortex and negative emotions e.g amagydala
