Neurobiology of Addiction Flashcards
What is the ICD-10 criteria for dependence?
Strong desire to take substance
Difficulties in controlling substance use
Physiological withdrawl state and tolerance
Neglect of alternative pleasures
Persistence despite evidence of harm
What is the ICD-11 definition of gaming disorder?
Pattern of gaming behaviour characterised by:
Impaired control over gaming
Increasing priority given to gaming over other activities to the extent that gaming takes precedence
Continuation/escalation of gaming despite the occurrence of negative consequences
What are the criteria under the ICD-11 for gaming disorder?
Behaviour pattern must be of sufficient severity to result in significant impairment in function
Should have been present for at least 12 months
How does the brain prioritise survival?
Identify, select and pursue behaviours that lead to important goals = need to prioritise these goals over others
What is incentive salience?
Attributing “want” to a stimulus = leads to appetitive and consummatory behaviour
What is the pathway that is involved in wanting?
The mesolimbic pathway
What is the function of the dopaminergic activity in the mesolimbic pathway?
Act as motivating signal
Incentivises behaviour
Involved in normal pleasurable experiences
What effect does addiction have on dopamine receptors?
Functionally decreases D2 receptors
What suggests that tolerance to reward develops in those with a gambling addiction?
Non-addicted individuals had increased blood flow to the striatum upon winning = gambling addicts had significantly less response
How does tolerance to reward develop?
Receptors downregulate due to repeated dopamine release = increases threshold for rewards during abstinence
What effect does tolerance to reward have?
Normal experiences don’t evoke adequate reward response = these changes persist despite prolonged abstinence from substance abuse
How does positive reinforcement become negative reinforcement?
Initial stages of drug taking are driven by reward and eventually drug taking becomes a thirst
What are the roles of the prefrontal cortex?
Helps intention guide behaviour
Modulates the effects of the reward pathway
Sets goals, focuses attention and makes sound decisions
Keeps emotions/impulses under control to achieve long term goals
How does cortical maturation occur?
Back to front direction = begins in primary motor cortex and spreads anteriorly over superior and inferior frontal gyri, prefrontal cortex develops last
When do frontal lobe areas that mediate executive functioning mature?
After the emotional (limbic) systems
What are some features of the brain activity of adolescents?
Show strong stimulus reward and minimal judgement or impulse control
What are the effects of dopamine release?
Updates information within the prefrontal cortex
Selecting new goals
Avoiding compulsive repetition of a behaviour
What effect do addictive drugs have on the prefrontal cortex?
Provide a potent signal that disrupts the normal dopamine-related learning in the prefrontal cortex
What parts of the brain are involved in forming drug habits?
Hippocampus and amygdala are critical in acquisition, consolidation and expression of drug stimulus learning = learned drug associations can then cue internal states of craving
What are the roles of the orbitofrontal cortex?
Provides internal representations of the saliency of events and assigns values to them
Key creator of motivation to act
How does the orbitofrontal cortex vary in addicts?
Show increased activation when presented with drug cues = hyperactivity correlates with self reported drug cravings following exposure to cues
Do changes on the orbitofrontal cortex resolve after addiction is resolved?
No = they persist into abstinence
How are genetics involved in addiction?
40-60% of risk is due to genetic factors
Low DRD2 receptor levels are at higher risk
What may genetics affect?
Way we respond to drugs metabolically
How rewarding we find a drug
Behavioural traits that predispose us to take drugs
What effect does acute stress have?
Triggers release of dopamine in the neural reward pathway
What does chronic stress lead to?
Dampening of dopaminergic activity through downregulation of D receptors = reduces sensitivity to normal rewards
How are stress and addiction linked?
Stress encourages exposure to highly rewarding behaviour = rapid increase in stress can motivate drug seeking in dependent individuals
