Addiction Flashcards
Who is more at risk for addiction
Women or men?
It is dependent on the drug but usually men. But the gap is closing. In women - telescoping (women move through the stages of drug addiction faster)
Who is more at risk for addiction
Young or old?
Often begins in adolescence. Teens have higher risk. Can often depend on how long you are using the drug for (and women telescope).
Who is more at risk for addiction
Mental health
Major relationship between mental health issues and drug use. People who have depression and anxiety, can be an effect of drugs or cause of drugs. cycle.
Who is more at risk for addiction
Genetics
Some evidence for genetic predisposition to addiction - just correlations but troubles with implicit bias in society/research.
Usually genes related to metabolism, the higher the metabolism the higher the risk.
Who is more at risk for addiction
Environment
Family history (confound with genes), poverty, chronic stress, early childhood adversity
What causes drug addiction?
Changes in the structure and function of the brain due to drugs
Drugs alter our motivation (from seeking other things to seeking the drug)
Features/ Criteria of drug addiction
Pleasing effects, Craving, Tolerance, Escalation of intake, Dependence, Relapse, Continued use despite adverse effects in life
Continued use despite adverse effects in life is a criteria that separates
‘being addicted to video games or coffee’ and actual addiction
Relapse
Even after abstinent, you go back to taking the drug
Dependence
New baseline
Withdraw effects
Tolerance
Adaptation within nervous system, leads to escalation of intake
Craving
Thinking about the drug even when not using
Stages of drug addiction
Intoxication
Development of dependence (withdraw)
Preoccupation and anticipation
Intoxication
Change from normal state. To intoxicate yourself
Development of dependence (withdraw)
Take the drug to feel normal.
Preoccupation and anticipation
Even when sober we think about the drug
Opponent process theory of drug addiction
Withdraw theory (Koob) We start taking drugs to feel good and continue to be normal and not feel withdraw Explains some (e.g. opioids)
Why is the opponent process theory of drug addiction wrong?
People go back to using drugs even after withdraw has passed (relapse). Drugs with high withdraw would correlate with addiction but the correlation is not close to 1:1. (Ex: cocaine had very short withdraw)
Reinforcement
behaviors that are rewarded will be repeated
Conditioned reinforcer/ incentive salience
A previously neutral stimulus acquires a motivational value. (ex: money, lever)
Olds and Milner (1954) - Rats press the lever to release dopamine from VTA to NAcc.
Rats do not stop doing this. Stop eating, having sex, or doing anything else until they collapse and die.
Motivation for brain stimulation
Dopamine projects from _____ to _______
Ventral Tegmental Area (VTA) to Nucleus Accubens (NAcc)
The ventral tegmental area projects its axons to NAcc
Dopamine is key in _________
Motivation
Evidences that dopamine is not the pleasure molecule
Parkinson’s disease - low dopamine but pleasure levels don’t go down
Schizophrenia - high dopamine but don’t have higher baseline pleasure
Parkinson’s disease brain
The brain is barely touched. The only place where the neurons have died is the substantia nigra pars compacta (SNs) Another main dopamine producer
L-DOPA
transforms into dopamine. Then can cross the blood-brain barrier: No change in baseline pleasure
Dopamine antagonists
Decreases motivation but not pleasure
Schizophrenia medications - anti-psychotics
Bind to dopamine receptors - antagonists. Block the function of dopamine.
Can be systemic or directly injected into NAcc or VTA
How do we know people with schizophrenia have higher dopamine levels?
Drugs that block dopamine receptors more strongly require less of a dose for schizophrenia patients to get better. (For positive symptoms of schizophrenia.)
John Salamone (1990’s) Low effort, low reward vs. high effort, high reward rat experiment
Rats chose high effort high reward
rat receives anti-psychotic injection - Dopamine receptor blockers.
Animals shift preference to low effort low reward
Rats are not motivated to work to get sugar when their dopamine receptors are blocked. If they can have it without working they will.
Incentive sensitization theory
Berridge and Robinson
Separates liking (pleasure) vs. wanting (motivation) Explains important elements that withdraw theory can not. Explains relapse
Incentive sensitization theory
Drug use adds Incentive Salience to drug stimuli
Via artificially increased dopamine levels
Sight of drug cues facilitates motivation (i.e. craving drug)
Incentive/ motivational Salience
motivation for rewards that is driven by both physiological states and previously learned associations about a reward cue
Drug use adds Incentive Salience to drug stimuli
The more a person uses a drug the more _____ increases while ______ decreases
Wanting increases while liking decreases
Shoultz et al. (1990s)
Pavlovian learning monkey experiment
Initial scenario
Unconditioned stimulus: grape juice = spike in dopamine.
Association of light and grape juice. Dopamine neurons don’t fire for grape juice anymore but for light.
Shoultz et al. (1990s)
Pavlovian learning monkey experiment
Final scenario
Pairing of juice and light remains. Withhold the reward (juice). When the grape juice does not come with the light, dopamine goes lower than baseline. Decrease in dopamine functioning.
VTA (Dopamine) Neurons
How do they work with rewards?
Fire at first for unexpected reward
Shift their firing to stimuli that predict reward
Go silent when predicted reward not delivered (RPE)
Can be chained forward in time.
Reward prediction error signal
Differences between received and predicted rewards
What dopamine actually tracks
It makes us strive for more rewards. We need this for motivation - survival.
Dopamine and incentives
Some stimuli have innate or learned incentives
Incentives facilitate dopamine release onto NAcc
These inputs guide behaviour
Basal ganglia
Habit formation and skill learning
Nucleus accumbens is part of __________.
part of basal ganglia.
What does the nucleus accumbens do?
Shapes behaviours (motor output)
Dopamine only goes up if…
There is a “surprise” reward
Incentives facilitate dopamine release onto NAcc
What signals can these releases be?
Teaching signal
Motivational signal
Other functions
The change in learning/memory systems due to drug abuse depends on …
how long and strongly a person uses a drug
The change in learning/memory systems due to drug abuse also changes…
personality, planning, reasoning, memory, etc
In long term drug abuse these are the only places that change in the brain:
The same targets of dopamine structures.
Detoxification therapy
Abstinence - not very useful
Drug replacement therapy
Can be successful, take dangerous drugs and replace them with a quality safe drug.
Behavioral/ Cognitive therapy
Help identify your own patterns of thought. Useful but not alone.
Twelve-step program therapy
Things like alcoholic anonymous. Support from community. works well overall
Challenges in treating drug addiction
Poverty, stress, cues, quality of life (Rat Park studies)
Not just about exposure to a drug
Changes in the dopamine system…
and
For the dopamine system to come back to normal, changes must…
Last long
The challenge in treating addiction - cycle
Adverse experiences —-> impaired Nucleus Acumbens function and altered dopamine profile ——> increased impulsivity, decreased behavioral flexibility —> Addiction —> impaired NAc function and altered Dopamine profile
Behavioral addictions share some similarities with drug addiction because…
Act on the same system (i.e. dopamine)
Reward circuits are active for natural rewards as well as drug rewards
Main difference between behavioral addictions and drug addiction:
the limits of behavioral addictions are natural. Artificial limits are higher than natural. (dopamine very high)
Dopamine agonist (to treat Parkinson’s) can cause
Impulse control disorders
- Problem gambling
- Hypersexuality
- Compulsive shopping
Dopamine is fundamental in our _______ system
motivational
Major component of addiction revolves around…
how drugs hijack the dopamine system but withdrawal symptoms is also a component of addiction
