Understanding Drug Addiction and SUDs

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Questions and Answers

What is the defining feature of SUD?

Psychological addiction

What is the main defining criteria for SUDs according to the DSM-5?

A cluster of cognitive, behavioral, and physiological symptoms

What is drug addiction?

A severe form of Substance Use Disorders characterized by compulsive drug seeking and use despite adverse consequences. It is considered a brain disorder because it involves functional changes to brain circuits that linger even after the person stops taking drugs.

What are the two main dopaminergic pathways directly linked to addiction?

Mesolimbic Pathway Signup and view all the answers

What is the nucleus accumbens associated with?

Reward and motivation Signup and view all the answers

Which brain regions are involved in the binge/intoxication stage of the addiction cycle?

Nucleus Accumbens (NAc) Signup and view all the answers

What is the dopamine depletion hypothesis of addiction?

The theory proposes that drug use depletes dopamine levels, leading to dysphoria and an increased motivation to use drugs to replenish the depletion. Since drug use itself is the cause of the dopamine reduction in the long run, it leads to a vicious cycle of drug seeking and addiction. Signup and view all the answers

What is the purpose of the Progressive Ratio (PR) procedure?

It measures an animal's breakpoint, which indicates how hard an animal is willing to work to receive drug infusions. Signup and view all the answers

The short access model of drug self-administration is used to model the transition from recreational to addictive-like behaviors.

False Signup and view all the answers

What is the difference between drug-induced vs. cue-induced reinstatement?

Drug-induced reinstatement measures the relapse triggered by re-exposure to the drug itself, while cue-induced reinstatement measures the relapse triggered by the exposure to stimuli associated with the drug. Signup and view all the answers

What is the purpose of using the compulsive drug-seeking procedure?

This model is used to illustrate how humans, despite facing negative consequences, will continue taking drugs. It models the compulsive nature of addiction by introducing a punisher with drug delivery. Signup and view all the answers

Which brain regions are involved in the withdrawal/negative affect stage of the addiction cycle?

Nucleus Accumbens (NAc) Signup and view all the answers

What is the difference between D1 and D2 like receptors?

D1Rs are associated with the expectation of reward and are primarily activated when dopamine levels peak. D2Rs, on the other hand, are involved in motivation for procurement and have a higher affinity for dopamine binding, leading to longer-lasting and persistent activation after dopamine levels subside. Signup and view all the answers

What is the difference in dopamine signaling between natural reinforcers and drugs of abuse?

With natural reinforcers, dopamine signals triggered by conditioned stimuli drive motivation, but cease upon consumption. Drugs of abuse, however, continuously increase dopamine release during consumption, leading to a sustained desire for the drug even during consumption. Signup and view all the answers

What is the main psychoactive compound in cannabis?

THC Signup and view all the answers

Which of the following are examples of psychostimulants?

Amphetamines Signup and view all the answers

What are the main effects of depressants?

Depressants increase sedation, making users feel calm and relaxed. They can slow down the central nervous system and lead to feelings of drowsiness, impaired coordination, and reduced cognitive function. Signup and view all the answers

What are the main effects of hallucinogens?

Hallucinogens distort perception, causing sensory experiences that are not real. They can alter a user's understanding of time and space, create hallucinations, and evoke intense emotional states. Signup and view all the answers

What are the main characteristics of entactogens?

Entactogens increase feelings of empathy and sympathy. They exhibit both psychostimulant and hallucinogenic properties and can lead to feelings of euphoria, connectedness, and openness. Signup and view all the answers

Inhalants are drugs that are primarily absorbed through the lungs.

True Signup and view all the answers

Which of the following is NOT a reason why people with SUD may not seek care?

Desire to keep using drugs Signup and view all the answers

Why might a person with SUD increase their substance use because of stigma and discrimination?

The stigma associated with SUDs often leads individuals to internalize negative beliefs about themselves, fostering feelings of guilt, shame, and isolation. This self-stigma can reinforce drug-seeking behavior as a coping mechanism for dealing with emotional distress. Signup and view all the answers

Where does the dopamine released in the VTA travel to?

The dopamine released in the VTA travels to the nucleus accumbens (NAc) and other brain regions through the mesolimbic and mesocortical pathways. Signup and view all the answers

What are the main functions of the prefrontal cortex?

The prefrontal cortex is responsible for executive functions, goal-directed behavior, and inhibitory control. It plays a crucial role in planning, decision-making, and regulating emotions. Signup and view all the answers

What is the role of the basal ganglia in addiction?

The basal ganglia, including the NAc and dorsal striatum, are involved in habit formation and the rewarding effects of substances. They contribute to the development of compulsive drug-seeking behaviors. Signup and view all the answers

What is the function of the extended amygdala?

The extended amygdala, including the NAc shell and the central nucleus of the amygdala, is involved in regulating negative emotional states associated with drug withdrawal, such as anxiety, irritability, and stress. Signup and view all the answers

What is the role of VMAT-2?

VMAT-2 is a transporter that moves dopamine and other neurotransmitters from the cytoplasm into vesicles for storage. Drugs can interact with VMAT-2, altering the availability and release of neurotransmitters. Signup and view all the answers

What is the mechanism of action of nicotine?

Nicotine is an agonist of nicotinic acetylcholine receptors. It directly depolarizes dopaminergic and glutamatergic neurons, triggering the release of dopamine. Signup and view all the answers

What is the mechanism of action of amphetamines?

Amphetamines reverse the flow of dopamine and norepinephrine transporters, causing the release of these neurotransmitters into the synapse. They also act as VMAT-2 reversers and inhibit MAO, further increasing the levels of dopamine and norepinephrine. Signup and view all the answers

What is the mechanism of action of MDMA?

MDMA is a serotonin, norepinephrine, and dopamine transporter inhibitor, with a greater effect on serotonin and norepinephrine transporters than dopamine transporters. It also inhibits VMAT-2 and MAO, leading to increased serotonin levels. Signup and view all the answers

What is the mechanism of action of depressants (including ethanol, sedative-hypnotics, and opioids)?

Depressants target GABAergic systems, increasing inhibitory neurotransmission. They do not directly affect monoamine systems. Signup and view all the answers

What is the mechanism of action of ethanol?

Ethanol blocks ionotropic glutamate receptors and increases GABAa receptor functioning, leading to enhanced inhibitory neurotransmission. Signup and view all the answers

What is the mechanism of action of opioids?

Opioids activate mu-opioid receptors expressed on GABAergic neurons, inhibiting their activity and increasing the release of dopamine. Signup and view all the answers

What is the mechanism of action of benzodiazepines and barbiturates?

Benzodiazepines and barbiturates are agonists at GABAa receptors, enhancing the inhibitory effects of GABA. Signup and view all the answers

What is the mechanism of action of cannabis (THC)?

THC is a partial agonist of cannabinoid receptors, particularly CB1 receptors, located on GABAergic neurons. This leads to a decrease in the activity of GABAergic neurons, which are responsible for inhibiting dopamine neurons, thereby increasing dopamine release. Signup and view all the answers

Study Notes

Drug Addiction

Severe biomedical disorder marked by compulsive substance use.
Substance Use Disorders (SUDs) involve repetitive behaviors despite negative consequences.
SUDs are classified as psychiatric disorders in the DSM and ICD.
Intoxication: temporary altered consciousness, cognition, perception, and behavior from drugs.
Tolerance: a response to repeated drug use where higher doses are needed for the desired effect.
Withdrawal: unpleasant symptoms from stopping drug use after prolonged use.
Physical Dependence: tolerance to drug effects and withdrawal symptoms upon cessation.
Psychological Dependence: behaviors interfering with daily life.
Physical Addiction: brain adaptation to the substance, seeking its effects to alleviate withdrawal.
Psychological Addiction: associating drugs with situations, people, or feelings, leading to relapse triggers.
Defining feature of SUDs (DSM-5): A cluster of cognitive, behavioral, and physiological symptoms.
Drug addiction is a severe SUD characterized by compulsive use despite harm. It's a brain disorder causing lasting changes in brain circuits.
DEA substance classification: government oversight of drug manufacturing and distribution.
Schedule 1 Drugs (DEA): high abuse potential, no accepted medical use.
Schedule V Drugs (DEA): low abuse potential, accepted medical use with limited dependency risk.
Abused drug types: psychostimulants, depressants, hallucinogens, entactogens, cannabis, and inhalants.

Psychostimulants

Nicotine, cocaine, methamphetamines, amphetamines, methylphenidate, and cathinones are included.
Nicotine: main psychoactive compound from tobacco leaves.
Cocaine: from coca leaves.
Methamphetamines, amphetamines, methylphenidate: synthetic.
Cathinones and synthetic cathinones: natural alkaloid and synthetic variants.

Hallucinogens

Distort sensory perceptions. Classic and dissociative categories.
Classic Hallucinogens: natural sources, rare fatal overdose, low withdrawal.
Dissociative Hallucinogens: synthetic, less rare fatal overdose, withdrawal symptoms.

Entactogens

Increase empathy and sympathy, stimulant and hallucinatory properties.
MDMA, MDA.
Fatal overdose risk is not uncommon and withdrawal symptoms are present.

Inhalants

Cause euphoria, dizziness, slurred speech, hallucinations, delusions.
Huffing, high overdose risk, death possible.
Withdrawal symptoms are present.

Cannabis and Synthetic Cannabinoids

Euphoria, impaired concentration, memory loss, anxiety, paranoia, delusions, hallucinations.
Natural or synthetic.
Uncommon fatal overdose.
Withdrawal symptoms.
CBD and THC are common compounds.

Depressants

Sedative properties, increased calmness.
Ethanol, sedative-hypnotics, and opioids.

Ethanol

Fermented from yeast, sugars, and starches.
Most frequently used drug in the US.

Sedative-Hypnotics

Anti-anxiety, sleep-inducing, and anesthetic properties.
Benzodiazepines and barbiturates.

Opioids

Intense euphoria and pain relief (analgesic).
Severe withdrawal symptoms, high overdose risk (e.g., fentanyl).
Heroin is highly addictive.

Opioid Overdose Waves

First wave: increased prescription opioid use.
Second wave: heroin accessibility and purity increased, decreased price.
Third wave: synthetic opioids like fentanyl, highly potent and easy to manufacture.

Behavioral Addiction

Frequent co-occurrence with substance use disorders.

Stigma and Discrimination

Fear of negative attitudes prevents seeking treatment.
Fear of bias and mistreatment results in avoidance of services.
Poorer quality care due to professional bias.
Limited access to health programs due to stigma.
Self-stigma and negative attitudes reinforce substance seeking behavior.
Belief that addiction is a personal choice.

Drug Mechanisms of Action

Cocaine: dopamine, norepinephrine, serotonin transporter inhibitors.
Amphetamines: reverse dopamine and norepinephrine transporters, and inhibit MAO.
Methamphetamine: potent amphetamine derivative, crosses blood-brain barrier more easily.
MDMA: inhibits dopamine, norepinephrine, and serotonin transporters, VMAT-2 inhibitor, and MAO inhibitor.
Nicotine: nicotinic acetylcholine receptor agonist, depolarizes neurons, activating dopamine release.
Depressants: target GABAergic system, not directly monoamine systems.
Ethanol: blocks ionotropic glutamate receptors, increases GABAa receptor function.
Opioids: activate mu-opioid receptors, inhibit GABAergic neurons.
Benzodiazepines and barbiturates: GABAa receptor agonists.
Cannabis (THC): partial CB receptor agonists, decrease GABAergic inhibition of dopamine neurons.

Brain Reward Pathways

Mesolimbic and mesocortical pathways are two key reward pathways.
Mesolimbic: Ventral tegmental area (VTA) to ventral striatum (NAcc).
Mesocortical: VTA to cerebral cortex.
Mesocorticolimbic pathway: motivation and reward circuitry.
Basal ganglia: habit formation, reward.
Extended amygdala: negative emotions associated with withdrawal (anxiety, stress).
Prefrontal cortex (PFC): executive function, goal-directed behavior, inhibitory control.
Parts of basal ganglia: NAc and dorsal striatum.
- NAc: motivation, reward, approach towards stimuli.
- Dorsal striatum: routine, habit formation.
Parts of extended amygdala: NAcc shell and central nucleus of amygdala.
- NAcc shell: pleasure.
- Amygdala central nucleus: reward associations, negative emotion.

Addiction Cycle

Binge/intoxication, withdrawal/negative affect, preoccupation/anticipation.

Addiction Brain Regions

Binge/intoxication: basal ganglia (NAcc, dorsal striatum).
Withdrawal/negative affect: NAcc, central nucleus of amygdala.
Preoccupation/anticipation: Prefrontal cortex (PFC).

Reward Prediction Error

Substance use creates associations between rewards and cues, triggering seeking behavior.

Dopamine Depletion Hypothesis

Dopamine depletion leads to dysphoria, driving drug seeking behavior to replenish the dopamine levels.

PFC Systems

Go system: anterior cingulate cortex and dorsolateral prefrontal cortex (goal-directed behavior, habits).
Stop system: ventrolateral prefrontal cortex and orbitofrontal cortex (inhibitory control, reducing stress responses).

Nucleus Accumbens (NAcc)

Pleasure center.
VTA response to reward cues, dopamine release in NAc (incentive salience).
Medium spiny neurons (MSNs): GABAergic neurons in NAc.
- D1 receptors: direct reward anticipation.
- D2 receptors: indirect motivation to obtain the reward.

Natural vs. Drug Reward

Natural reinforcers: dopamine release stops after consumption.
Drugs of abuse: continued dopamine release, sustained motivation for continued consumption even during consumption.

Modeling Addiction in Animals

Short access model: tolerance testing.
Long access model: models escalation and addictive behaviors.
Progressive ratio: measures the breakpoint (effort for a reward).
Extinction-reinstatement: models relapse.

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Description

This quiz explores the complexities of drug addiction and substance use disorders (SUDs), focusing on their biomedical characteristics and the distinctions between physical and psychological dependence. Learn about the symptoms, classifications, and effects of substance use, as well as the challenges of tolerance and withdrawal. Test your knowledge on this critical mental health issue.