Drug Addiction 1 Flashcards
What is 1) habitual drug use, 2)drug seeking behavior and 3)physical dependence?
1) habit: persist in spite of adverse effects. Even after remission periods, you can have chronic relapsing disorder
2. drug seeking. lots of time spent thinking about craving and acquiring the drug. certain triggers can prompt craving and relesae
3. physical dependence. suffer from withdrawal after use that motivate return to use. (especially with severe effects, sepends on the drug and the person)
what is the definition of withdrawal?
body’s reaction to elimination of a drug from the system after repeated exposure.
- opposite of drug’s action (sleeping pill withdrawal will cause insomnia)
- body initiates compensatory physiological mechanisms (tolerance) to maintain homeostasis to do the opposite of what the drug does
- when drugs cleared from system, those changes linger and cause withdrawal symptoms.
Taking drugs takes symptoms away.
person who wants more drugs to take away the sympoms becoems physically dependent.
why isn’t withdrawl the whole story for drug addiction?
withdrawal may last a few days but people can be addicts for life.
chronic relapsing and something else drives them back.
What is conditioned withdrawal?
cues associated with drug taking: trigger withdrawal like sensations. its like the opposite to conditioned tolerance
what is the medical definition of addiction?
addiction and addict: not ok! its substance use disorder.
needs: maladaptive pattern for 12 months that leads to impairment or distress and 2 other criteria
How does the route of administration influence development/maintenance of addiction.
influences potential of a substance
- IV injection or inhalation or snorting makes drug entry RAPID. oral transdermal routes have slow absorption (even if they may last longer).
- faster onset: more likely to be addictive.
- IV and fast stuff is strongest euphoric effect
- repeated exposure leads to development of neurobiological changes of addiction
Describe genetic variation of drug addiction?
may contribute to vulnerability
- majority focused on alcoholism
- monozygotic twins more concordant for alcoholism than dizigotic twins
Polymorphisms: genes that influence addiciton susceptibility. alter how a protein of gene encodes. decrease its activity. effect how it affects neural activity or responses to drugs. (just like a reuptake transporter)
Who is more likely to be an alcoholic?
those with higher tolerance, who metabolize EtOH quicker.
Other genes: Gaba-a receptor subunits 5ht transporter dopamine d4 receptors opioid receptors (bUT HOW THESE THINGS DO CHANGES IS NOT CLEAR)
What factors increase likelihood of nicotine addiction?
Genes that code for enzymes involved in nicotine metabolism and nicotinic receptors.
but even then there are individual differences (in the same strain)
what are the simple theories for addiction and what are the problems with them?
1) Physical dependence model: desire to curb withdrawal symptoms
Problems:
a) relapse occurs after withdrawal has passed. (detoxified users remain addicted)
b) some drugs don’t have severe withdrawal (cocaine)
c) treatments used to curb withdrawal (nicotine patches aren’t super effective)
- Positive Reward Model: addiction driven by pleasureable feelings of drugs
Problems:
a) drug can continue even when “rush” dies down (tolerance to hedonic effects)
b) some drugs don’t give as much euphoric rush as others but are still addictive (nicotine)
what brain region is responsible for rewarding/reinforcing aspects of abused drugs?
Reward circuit! Changes in this circuit drive the behaviors.
- PFC
- Amygdala
- NAc
- DA
What nodes are part of the reward circuit?
PFC: executive, flexibility, emotional regulation, stress response, behavioral inhibitoin
- reciprocally connected with amygdala.
Amygdala: different subnuclei regulate learning about reward-precitive cues (basolateral nucleus) and mediates response to stress (Central nucleus)
Nucleus Accumbens: ventral striatum, motivational aspects of reward and approach towards reward related stimuli
Both PFC and AMyg send projections to NAC.
DA: DA projections to all of them (especially from VTA to NAc)
Whats the function of dopamine?
sensitive to cues associated with rewards and absence of expected rewards (monkey reward prediction errors experiment)
- Dop turns on when something important happens to make you learn things about reward related cues and what will increase the chances that it’ll happen again.
When you see a sitmulus associated with reward: increases DA system that makes you say REMEMBER THIS.
what do all drugs of abuse with high addictive potential act on?
Directly or indirectly act on mesolimbic DA system.
- same one as natural rewards (like food or sex) especiall when learning cues associated with rewards.
Drugs is 10x greater activation than natural rewards (400% rather than 50%)
This can trick the brain into thinking drugs are important (cause of dopamine surge) and forming associations with cues and drug taking
what is the difference between positive reinforcers and drug reward?
reinforcers: strenghens whatever preceding behavior was perfomed. makes someone more likely to take it again.
drug reward: subjective experience (the high, euphoria)
if you see changes in reinforcing quality, you don’t know if its “rewarding”. Reward is not drug reinforcement.
Liking isn’t the same as wanting.
Reward has 2 components.
Liking (pleasurable, hedonic effects) is different than wanting (craving, willingness to work for reward)
