PDA III - Exam 4: Drug Abuse RW

What behaviors define addiction?

Compulsive drug seeking and drug abuse

Chronic condition consisting of remissions and relapses

What is the term for a diagnosis of addiction?

Substance use disorder

How is substance abuse disorder measured?

Measured on a continuum from mild to severe

How many criteria must a patient have to be diagnosed with a substance use disorder?

≥2 criteria

What is mild substance use disorder defined as?

2-3 criteria

What is moderate substance use disorder defined as?

5-6 criteria

What is severe substance use disorder defined as?

≥6 criteria

What are criteria for diagnosis of a substance use disorder?

Hazardous use

Social/interpersonal problems related to use

Neglecting major roles to use

Withdrawal

Tolerance

Used larger amounts/longer than planned

Repeated attempts to quit/control use

Much of time spent using and recovering

Physical/psychological problems related to use

Activities given up to use

Craving

What is the "continuum of drug use"?

A continuum of drug use

In terms of the amount, pattern, and consequences

How do people move through the "continuum of drug use"?

When first use a drug can move anywhere along continuum

Even hard-drugs are not instantly/automatically addictive

People can move in all directions along continuum

People with drug addiction shift along the continuum, shifts vary greatly between people

What type of disorder is drug addiction?

Drug addiction is a chronic-relapsing disorder

Pattern varies greatly from individual to individual

What is described by the Gateway Theory of drug use?

Use of "gateway" drugs leads to later use of more serious drugs

Strongly implies that experimentation with lesser drugs causes the eventual experimentation with harder drugs

What are weaknesses of the Gateway Theory of Substance abuse?

Study relied on school surveys

(sampling bias)

Studies didn't prove causality

(post hoc, ergo propter hoc)

Other factors may cause use of one drug to reliably precede another

What is conditioned place preference?

Association of a space with a reward (drug)

What conditioned place preference experiment supports the gateway hypothesis?

Rats exposed to nicotine prefer cocaine more than unexposed rats

Nicotine made the cocaine more rewarding

increased cocaine seeking behavior

What is Pavlovian (classical) conditioning?

Associating of a response with a conditioned stimulus

Conditioned responses

Conditioning may contribute to drug abuse (seek drugs when come into contact with conditioned stimuli)

How can drug paraphernalia cause a conditioned response?

Associate rewarding effects of a drug with the drug paraphernalia

What is conditioned withdrawal?

Having withdrawal symptoms (or cravings for the drug) in places or situations the drug has been used in the past

Feel withdrawal even when no longer physically dependent

What is operant conditioning?

Behavior followed by reward or punishment

Reward inc. likelihood of behavior

Punishment dec. likelihood of behavior

What is the positive reinforcement model of drug abuse?

Euphoria from drug acts as reward

Positively reinforces future use

What is evidence for the positive reinforcement model of drug abuse?

Animals self-administering drugs

What is animal drug self-administration used to study?

Quantify how rewarding a drug is

Relationship between the rewarding properties and dose of a drug

What are shortcomings of the positive reinforcement model?

Drug craving increases

But, there is tolerance to the euphoria

What is delayed discounting?

The further in the future a stimulus is the less power it has over behavior

Minimizing punishment and making reward more powerful

Temporal discounting of delayed stimuli

Reason negative consequences of abuse don't counteract the positive reinforcement from drug-induced euphoria

What are the main areas of the reward circuit?

Nucleus accumbens (NA)

Ventral tegmental area (VTA)

What are the other names for the nucleus accumbens?

Ventral striatum

Emotional striatum

How are the NA and VTA connected in the reward circuit?

Dopaminergic input from the VTA to the NA

Connection made by medial forebrain bundle

What are characteristics of DA receptors on nucleus accumbens neurons?

DA receptors in the nucleus accumbens are D2 (Gi)

When DA is release it inhibits the nucleus accumbens

Corresponding to subjective feeling of pleasure

How do opioids cause reward in the reward circuit by acting in the VTA?

GABA interneurons in the VTA are responsible for inhibiting the dopaminergic neurons

Inhibiting the reward circuit

Mu opioid receptors are inhibitory (Gi)

Found on GABA interneurons

Stim. of opioid receptors by opioids inhibits GABA neurons

Causes disinhibition

Activating the reward circuit

How do opioids cause reward in the reward circuit by acting in the nucleus accumbens?

Accumbens neurons have mu (Gi) receptors

Opioids act directly at nucleus accumbens and inhibit it

Pleasure signaling

How does alcohol cause reward in the reward circuit?

Inhibits GABA neurons in the VTA

(disinhibition)

Turning on the VTA

Causing reward

How does nicotine cause reward in the reward circuit?

Activates dopaminergic pathway

AND activates release of endogenous opioids in the nucleus accumbens

How does nicotine activate the dopaminergic pathway?

Nicotine stim.'s dopaminergic neurons of reward pathway

By action at nicotinic receptors in the VTA

DA neurons in VTA have ionotropic nicotinic receptors

Nicotine stim. nicotinic receptors

Na channels open

Na influx

Depolarization

DA release

How does nicotine cause release of endogenous opioids in the NA?

Nicotinic receptors present on opioid neurons

Nicotine stim. opioid receptors

Causes release of endogenous opioids in the nucleus accumbens

Leading to inhibition of the nucleus accumbens

Which causes reward/pleasure

How does cocaine cause reward in the reward circuit?

Blocks DA transporters

Increased DA levels in the nucleus accumbens

How does amphetamine cause reward in the reward circuit?

Increases DA release

Increased DA levels in the nucleus accumbens

How does PCP cause reward in the reward circuit?

Antagonizes inotropic Glu receptors on nucleus accumbens neurons

Blocking excitation of NA

Inc inhibition of NA

Pleasure

What is the effect of Glutamate neurons in the nucleus accumbens?

Glu excites the nucleus accumbens

Opposite of reward