Flashcards in Lecture 29 - Behavioural and Clinical Aspects of Drug Dependence Deck (9)
Parts of the brain particularly involved in drug dependence
Ventral temental area and nucleus accumbens projecting to the cortex
How does heroin affect the brain?
Binds to opioid receptors on GABA interneurons in the ventral tegmental area. This disinhibits VTA, leading to dopamine release
Heroin relapse rates
42% relapse within days of leaving detox
66% addicted 6 months after detox
48% still using after 6 years.
5% in prison
Aspects of physical dependence
Tolerance to drug, withdrawl
How can drug dependence lead to anhedonia?
Setpoint of dopamine-releasing reward system is set lower and lower. Requires greater stimulus to release dopamine
Evidence for conditioning aspect to drug addiction
Heroin addicts overly-responsive to opiate-related pictures, under-reactive to naturally-rewarding images
Brain areas affected by drug addiction
Orbitofrontal cortex (role in making choices)
Anterior cingulate cortex (role in long-term goals)
Outcomes of behavioural tests on drug addicts
1) Require more of the brain to be active to perform the same tasks as unaddicted people
2) Perform poorly on gambling tasks (always pick higher-stakes options, even though they know that they shouldn't)