Flashcards in 3.11 Neurobiology of Addiction Deck (14):
What are the ICD-10 Criteria for "Dependence"?
1. Strong desire
2. Difficulties controlling
3. Physiological withdrawal
5. Neglect other pleasures
6. Persist despite evidence of harm
What does CAGE stand for in addiction assessment?
C- Cut down
E- Eye opener
What three parts of the brain are particularly in the reward pathway?
1. Prefrontal cortex
2. Nucleus accumbens
3. Ventral tegmental Area
Dopaminergic activity in this mesolimbic pathway is motivating, incentivising, and is involved also in normal pleasurable experiences.
Rats will stumulate which 2 areas of the brain to the exclusion of food/sex/water and accept pain until they starve to death?
1. VTA- Ventral tegmental area
2. NA- Nucleus accumbens
These behaviours can be blocked with dopamine ANTAGONISTS
What is the change compared to controls in D2 receptors in addiction?
D2 dopamine receptors are decreased by addiction.
This may be linked to increased tolerance to reward
What is the role of the Orbito-frontal cortex?
What changes can be seen in addiction?
The orbitofrontal cortex provides internal representations of events and their values.
It motivates actions.
In addicts, there is increased activation of the OFC when presented with drug cues. Hyperactivity of OFC correlated to cravings of drugs following cues.
Overall changes persist in OFC after abstinence.
What is the general role of the prefrontal cortex?
Modulates reward pathway
Makes sound decisions
Keeps emotions and impulses under control to achieve long term goals
What is the order of frontal lobe maturation?
Back to front through the frontal lobe.
1. Primary motor cortex
2. superior and inferior frontal gyri
3. Prefrontal cortex
What does dopamine release do in the pre-frontal cortex?
Dopamine release affects:
-ability to update info within PFC
-ability to set new goals
-ability to avoid compulsive repetitive behaviour
DRUGS disrupt the normal dopamine related learning in the prefrontal cortex.
What are the roles of the following in addiction:
Striatum- habit learning
Hippocampus- Declarative learning
Also the amygdala, are critical in acquisition, consolidation, and expression of drug stimulus learning. They trigger craving.
What % of addiction risk is due to genetic factors?
This is the most heritable complex psychiatric condition.
-behavioural traits predisposing
-rewarding sensation from drugs
-Receptor levels- Low DRD2 = higher risk
What neurochemical event follows acute stress in the dependent individual?
Release of dopamine in the neural reward pathway- that can motivate drug seeking.
What is the effect of chronic stress in the dependent individual?
Dampening of dopaminergic activity via downregulation of D receptors
= reduced sensitivity to normal rewards