Neurobiology of Addiction Flashcards
What are the 2 main models of addiction?
Moral (people who use drugs are doing so for purely selfish reasons)
Medical; people who are addicted leads to neurobiological changes that gradually undermine the persons ability to practice free will surrounding drug use
ICD 10 criteria for dependence
A strong desire to take the substance Difficulties in controlling substance use A physiological withdrawal state Tolerance Neglect of alternative pleasures Persistence despite evidence of harm
What is CAGE?
Cut-down
Annoyed
Guilty
Eye-opener
What areas of the brain are involved in the motivational (mesolimbic) pathway?
VTA (ventral tegmental area)
Nucleus accumbens
Prefrontal cortex
Dopamine is the motivating signal, incentivises behaviour, involved in normal pleasurable experiences
Where will alcohol, nicotine and opiates act?
Nucleus accumbens to release dopamine
How do cocaine and amphetamines result in dopamine release?
Act directly on dopamine receptors
What can be seen in terms of MRI scans of those with addictive behaviour?
TOLERANCE
Non-addicted have increased blood flow to striatum to winning at gambling when compared to those who are addicted to gambling
Are dopamine receptors increased or decreased in addiction?
Decreased
Due to repeated dopamine release, dopamine receptors down regulate and therefore the threshold for rewards during abstinence is decreased and normal experiences don’t evoke an adequate reward response
What is the role of the PFC in addiction?
Helps intention guide behaviour
Modulates the powerful effects of the reward pathway
Sets goals, focuses attention
Makes sound decisions
Keeps emotions and impulses under control to achieve long term gaols
What is the effect of dopamine release?
Ability to uptake new information in the PFC
Ability to select new goals
Ability to avoid compulsive repetitive behaviour
What are the hippocampus, striatum and amygdala involved in in terms of addiction?
Acquisition
Consolidation
Expression of drug stimulus learning
What is the role of the orbitofrontal cortex in addiction behaviour?
Provides internal representation of the salience of events and assigns values to them
Key creator of motivation to act
What impact does genetics have on addictive behaviour?
Way we respond to drug metabolism
Behavioural traits that predispose us to take drugs
How rewarding we find drug taking
Receptor levels; low DRD2 = high risk
What is the impact of stress on addictive behaviour?
Acute stress = dopamine release in neural reward pathways
Chronic stress = dampening of dopaminergic activity through down regulation of D receptors
