L11 Substance abuse

What is substance abuse disorder?

A pattern of drug use involving chronic, excessive use

What does addiction or dependence mean in this context?

Being physically dependent on a drug in addition to abusing it.

5 types of substances to abuse

cocaine, designer drugs, intravenous drugs, alcohol and smoking

What is positive reinforcement in drug use?

The addition of a rewarding stimulus after a behavior, increasing the likelihood of repeating the behavior.

Why is heroin more addictive than morphine?

Heroin has a faster effect, making it more reinforcing.

Which brain area is central to the reinforcement of drug use?

The nucleus accumbens (NAC)

Where in the brain does the process of addiction begin

the mesolimbic dopaminergic system

Where do long term changes in the brain occur

ventral tegmental area (VTA)

What do changes in the VTA lead to

increased activation in a variety of regions that receive dopaminergic input from the VTA

When do synaptic changes responsible for compulsive behaviours occur

after continued use

Why are changes in the dorsal striatum important

it is part of the basal ganglia which plays a critical role in instrumental conditioning

3 factors contributing to the negative reinforcement in drug use

tolerance, withdrawal symptoms, address mental problems

What 2 things cause cravings and relapse?

Long-lasting brain changes and conditioned responses to drug-related stimuli

What is attentional bias in addiction?

Cravings triggered by cognitive focus and dopamine release in response to cues.

What neurotransmitters plays an important role in the positive reinforcement of drug use and craving/relapse

dopamine

What brain area regulates emotion and control related to addiction?

The prefrontal cortex (PFC)

What is the most commonly abused opiate

heroin

What are 4 affects of stimulating opiate receptors

analgesia, hypothermia, sedation and reinforcement

Where do opiate related stimuli trigger the release of dopamine

nucleus accumbens (NAC)

What did Wise et al. (1995) find about heroin in rats?

Heroin increased dopamine in the NAC by 150-300%, and rats self-administered it.

How do cocaine and amphetamines differ in their action?

Cocaine blocks dopamine reuptake; amphetamines both block reuptake and directly stimulate release.

Why are cocaine and amphetamines highly addictive?

They heavily activate the mesolimbic dopamine system

What is the leading cause of preventable death in the uk

smoking

2 ways nicotine affect the brain?

It stimulates nicotinic receptors and increases dopamine release in the NAC.

What can disrupt smoking addiction

damage to the insula

4 potential effects of alcohol

mild euphoria, anxiolytic (reduce anxiety), disinhibition and alcohol myopia (disrupted judgment)

What activity and where does alcohol increase

dopaminergic neurons of the mesolimbic system

What 2 neurotransmitter systems (+ type) does alcohol affect?

increase GABA (indirect agonist) and decrease NMDA (indirect antagonist) systems.

Consequences of withdrawal from alcohol

seizures and convulsions

2 ways alcohol reinforcement is mediated beyond dopamine?

Through the release of endogenous opioids and activation of opioid receptors.

What is Korsakoff’s syndrome?

Memory disorder caused by lack of vitamin B1, often due to chronic alcohol abuse.

What brain area does Korsakoff syndrome impact

thalamus (important for encoding new memories)

What is THC and its main receptor?

THC is the psychoactive component of cannabis; it acts on CB1 receptors.

How does THC affect dopamine?

It stimulates dopamine release in the nucleus accumbens.

What did Kendler et al. (2003) find about drug abuse risk?

Environment influences use; genetics influences dependence.

What is the estimated genetic contribution to vulnerability to addiction?

Around 40–60%

2 genetic variability influencing heredity of addiction

metabolism and sensitivity to drugs.

What 2 treatments exist for opiate addiction?

Methadone (replacement drug) and buprenorphine (block effects of opiates)