MECHANISMS OF ADDICTION Flashcards
What is addiction?
The continued repetition of a behaviour despite adverse consequences. May continue to point of death.
Outline the cycle of addiction.
Social drinking ->abusive drinking -> dependence and altered brain function -> excessive and uncontrolled drinking -> abstinence -> acute/protracted withdrawal symptoms -> relapse.
Describe end-stage addiction?
Overwhelming desire to take the drug, diminished ability to control drug seeking, reduced pleasure from biological rewards -> drug becomes most salient (important) thing in their life.
What structural changes occur in the brain in addiction?
Addicts take alcohol/drugs so often it becomes an automatic habit due to changes in the prefrontal cortex -> over learning of drug-related cues and can be triggered by cues years after abstinence.
Outline dependence syndrome.
- Salience - use of substance is high priority.
- Tolerance
- Withdrawal symptoms - body’s homeostasis disrupted.
- Relief from symptoms with further use.
- Compulsion to use substance
- Narrowing of repertoire - neglect of other interests
- Reinstatement after abstinence - 1 drink ruins it all
Define pre-contemplation?
People are not intending to take action and can be unaware that their behaviour is problematic.
Define contemplation?
People are beginning to recognise that their behaviour is problematic and start to look at the pros and cons of their continued actions.
Do some people have a vulnerability to addiction?
The alcohol gene - 25% of the sons of alcoholics develop alcohol problems themselves -> definite genetic risk of alcoholism but no single gene.
Twin studies - 4 good studies show increased concordance for monozygotic over dizygotic.
Adoption studies - 3 - 4x increase in risk in adoptees raised apart.
Describe the asian flush.
Flush reaction in 50% of asians due to variant of acetaldehyde dehydrogenase gene -> slow metabolism of alcohol.
What maintains addiction?
- Personality factors - thrill seeking, impulsive, mood dysregulation.
- Social factors - substance use amongst family and friends.
- Altered physiology in continuous presence of drug - homeostasis altered so can’t function properly without the drug.
Unpleasant effects when drug is absent - withdrawal -> strong negative reinforcement.
Discuss the environmental influences on addiction.
Severely distressed animals like people will relieve their distress pharmacologically if they can.
How does addiction occur?
Drugs have highly positive reinforcing effect - high.
Negative reinforcement - feeling hungover/withdrawal - helped by more drinking.
What is the role of dopamine in addiction?
Dopamine levels spike with many pleasurable activities i.e. sex, eating.
All addictive drugs lead to increased dopamine levels in nucleus accumbens.
the system becomes more linked to the imprtance of an activity -> things that activate dopamine reward system become more important.
Addicts become less sensitive to natural reinforcers and substances become more salient.
What can you get addicted to?
Alcohol, drugs (legal - benzodiazepines, opiates, illegal - heroin, cocaine), gambling.
Activities associated with pleasure and activates dopamine reward system - sex, eating, porn, video games, shopping, exercise.
What makes a substance addictive?
- pleasure producing potency
- rapid onset of action
- short duration of action
- tolerance and withdrawal
