Lecture 30 - Behavioural and developmental aspects of drug dependence Flashcards
Where is the dopaminergic system?
starts in the ventral tegmental area
projects forward to the nucleus accumbens and then to the prefrontal cortex
key in reinforcement of learning - ensures behaviours linked to survival are repeated - drugs can hijack this system
How does cocaine act?
blocks the re-uptake of dopamine at the synaptic cleft - causes more post-sympatic actvation
How does heroin and cannabis work?
works n the VTA -
GABA interneurons normally switch off the dompmne system - heroin binds to the opiate receptors, and open Cl channels and switches off GABA interneuron (dis-inhibition) = more dopamine released
Cannabis works in a similar way by binding to DP1 receptors
What is physiological dependence?
tolerance - homeostatic mechanisms, mean the body works against the drug more and more as you take it
withdrawal - symptoms of the reverse of the drugs effect - a result of the counteractive mechanism being in place without the drug there
Happens to everyone - but addiction is more like psychological dependence
What does psychological addition lead to?
time spent doing activities to obtain/use drug
think about using drug all the time
What causes Heroin relapse rates?
psychological dependence
how is conditioning relevant for psychological dependence?
pairing drug withdrawal with other things/situations/environments
The system becomes sensitized
With drug use, the homeostatic point changes so that normal things that gives pleasure…
no longer give the same mood response - the dopamine levels have been used up and it takes a larger increase in dopamine to get the same mood response
Drug users don’t find normal things pleasurable, can’t distract themselves - anhedonia
What does the orbital frontal cortex do?
Weighs up short/long term consequences
keep you on track to your goals
people with addiction so lack of activity
Does addiction cause all these CNS problems or are people who get addicted already predisposed to these behaviours?
adolescent anhedonia may continue into adulthood in some
What is the function of adolescent anhedonia?
increase in levels of boredom and disinterest is evolutionarily imporatnt as it causes pursuit of new appetite reinforcers through increase in risk taking and novelty-seeking
The full development of the brain is linear, meaning…
it starts from the back and goes forward - parts to do with judging logic and reason are last to fully develop
Young people are more vulnerable to alcohol-induced ____ impairments
memory - blackouts common in young drinkers
there is evdidence of premorbid neurobiological vulnerabilities in ….
at risk populations
