neuro: drug use, addiction and the brains reward circuits Flashcards
what is the idea behind physical dependence theories of addiction
traps addicts in a viscous cycle of drug taking and withdrawal symptoms
what did early drug addiction programmes involve and why were they unsuccessful?
→ withdrawing drugs from addicts in a hospital environment
didn’t work because:
→ some highly addictive drugs don’t produce severe withdrawal distress
→ patterns of drug taking involves cycles of binges and detoxification
habitual drug users, continue to use drug despite its adverse effects on health and social life, despite repeated efforts to stop using. what type of individual is this?
drug addicted individuals
theory that people take rugs to obtain positive effects not to escape or avoid the unpleasant consequences.
positive incentive theories of addiction
what is the most important factor of positive incentive theories?
the drugs HEDONIC (pleasurable) effects
how does the ICSS paradigm support the positive incentive theory?
ICSS = intracranial self stimulation
→ rats, humans, other species will self administer bursts of electrical stimulation to own brains → pleasure centres → mesotelencephalic dopamine system
what are the different explanations of drug taking?
peer pressure, social and environmental stress, prior life experiences, novelty seeking, useful (alcohol and caffeine)
why do some people become addicted?
→ experience hedonic effects → + incentive theories
→ have a need for drug
→ incentive-sensitisation theory
state of decreased sensitivity to a drug that develops as a result of exposure to it =
tolerance
how can tolerance be shown with drug taking?
→ given dose has less effect than it had before drug exposure
→ takes more of the drug to produce same effect
what is cross tolerance?
when one drug can produce tolerance to other drugs that act by the same mechanism
sensitisation is the ______ of tolerance
opposite (inverse)
increasing sensitivity to a drug =
drug sensitisation
what happens when the pleasurable effects of cocaine become sensitised?
gives the compulsion to take more of the drug with repeated use
withdrawal =
drug dependence
after significant amounts of a drug has been in the body for a period of time its sudden elimination can trigger adverse physiological reaction =
withdrawal
give an example of how the effect of drug withdrawal shows the opposite effects of what the drug does
sleeping pills → withdrawal effect = insomnia
longer exposure to _____ doses = ______ withdrawal effects and dependence
greater, greater
tolerance only develops to drug effects that are experienced. what tolerance is this?
contingent
maximal tolerance effects are seen in the environment in which the drug has been taken. what tolerance is this?
conditioned
describe before and after experiment to show the effect of contingent tolerance
CONTINGENT TOLERANCE TO ANTICONVULSANT EFFECTS OF ALCOHOL
→ 2 groups of rats receive alcohol injections (1 injection every 2 days)
group 1 → injection one hour BEFORE mild convulsive stimulation (allows anti convulsant effects of alcohol to be experienced)
group 2 → injection one hour AFTER mild convulsive stimulation (effect of alcohol can’t be experienced)
→ end of experiment → rats receive injection and then stimulation
results:
rats that had alcohol before became tolerant to anticonvulsant effects so had increased duration seizure, rats who had it after developed no tolerance so had lower duration seizure
describe the rat study that shows the effect of conditioned tolerance
→ 2 groups of rats received 20 alcohol and 20 saline injections
group 1 = 20 alcohol injections in colony room and 20 saline injections in distinctive room
group 2 = other way round
→ after all injections tolerance of hypothermic effects of alcohol were tested in both environments
results:
tolerance to cold only observed in environment where rat was given alcohol injections
shows situation specifity of drug tolerance, idea that drug users may be susceptible to lethal effects of overdose when drug is taken in new context due to lowered tolerance