Substance use and addiction Flashcards
What are the three main reasons people may choose to take drugs/alcohol?
Feel high/Elation/escapism/like it (positive reinforcement),
Sleep/Stress Manage/Withdrawal (negative reinforcement), Society pressure
Course of drug use
like -> want -> need
starts with experimental use which becomes increasingly regular use then eventually spirals into dependence.
What are the diagnostic criteria for dependence syndrome?
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ICD-10:
1. Compulsion to take drug,
2. Control difficulties, onset, termination and levels of use
3. Withdrawal state, user takes drug to treat this
4. Tolerance, need more to get the same effect
5. Neglect to enjoy activities,
6. Persistent use despite harm
What is addiction?
Compulsive drug use despite harmful consequences, characterised by an inability to stop, failure to meet work, social or family obligations, tolerance and withdrawal
What is dependence?
Physical adaptation to a substance which cause cause tolerance/ withdrawal.
What is the difference between addiction and dependence?
Addiction - compulsive use despite harmful consequences // Dependence - biological tolerance to substance
What are some behavioural addictions?
Gambling disorder, internet gaming disorder
What is hazardous use?
Drug use is likely to cause harm if it is continued at this level
What is harmful use of drugs (with examples)?
Actual damage to physical or mental health of user or those around them.
E.g. smoking with lung disease or getting drunk and fighting
What are the three stages of abnormal drug and alcohol use?
Hazardous Use, Harmful Use, Dependence/Addiction
Effect of speeding up brain entry
Causes a greater rush an more addiction
e.g. tobacco used to be chewed, but now it is smoked as it gets to the brain faster
Influences on drug use and addiction
social/environmental factors
drug factors
personal factors e.g genetic, personality traits
What occurs during tolerance?
Compensatory neuroadaptations to maintain normal brain function
Describe the natural reward pathway in the brain
Dopamine pathway: dopaminergic neurons that originate in the ventral striatum and project to the substantia nigra
What is the mechanism of action of amphetamine at the dopaminergic neurons?
Blocks reuptake of dopamine and releases extracellular dopamine
How can you assess the function of the reward pathway?
Functional MRI of ventral striatum and a reward incentive delayed anticipation task (asking to roll two die and if they get 12 then they win something - see ventral striatum activity)
How can reward deficiency lead to drug use?
Blunted brain activation of the reward system suggested that those people were more likely to become problematic drug users (often relapse)
How is reward system proficiency related to abstinence?
Higher activity in reward system is associated with higher rates of abstinence after drug use
What parts of the brain are related to the withdrawal effects?
Amygdala, hippocampus and brainstem
Amygdala and drug abuse
Subconscious stress receptor
Activity is dampened by drugs, so in abstinent individuals it becomes overactive
Chronic alcohol abuse effect on the brain
Impaired frontal cortex, which causes impaired DM and mood swings.
What is the mechanism of action of alcohol, opiates and nicotine at the dopaminergic neurons?
Increased dopaminergic neuron firing rate
What is the mechanism of action of cocaine at the dopaminergic neurons?
Block reuptake of dopamine
How does the type of reinforcement as addiction develops?
Changes from positive to negative reinforcement
What amygdala system is disrupted in withdrawal states and how?
Increased activity in amygdala stress system: increased activity in kappa opioid and noradrenaline (anxiety and arousal)
Causes of impulsivity/ compulsivity
Fronto-striatal connections with reduced frontal control of striatal activity and move from ventral (limbic) to dorsal (habit) striatum as dependence develops.
How does alcohol alter the balance of the brain’s inhibitory system?
Increases the action of the GABA-A receptor, and hence the inhibitory system
Causes Anxiolysis (relaxed), Sedation
How does alcohol alter the balance of the brain’s excitatory system?
Decreases the action of the NMDA glutamate receptor, and hence the excitatory system
Causes Impaired memory (alcoholic blackouts)
What is the brain’s compensatory mechanism to alcohol effects?
Neuroadaptations - reduced sensitivity of GABA-A to alcohol // upregulation of excitatory effects
How does tolerance of alcohol cause the negative effects of withdrawal?
Loss of balance - higher excitatory system effects than inhibitory functions
NMDA receptor causes increased ca2+ activity leading to Hyperexcitability (seizures) and Cell Atrophy
How would you treat alcohol tolerance?
Benzodiazepine - boost GABA-A effects
What drug can you use to support abstinence?
Acamprostate (new drug) - blocks NMDA receptor
