Addiction, Dysregulation of Reward and Allostasis (Koob 2001)

Question 1

What is the addiction cycle?

Answer 1

A proposed model to explain the spiralling dysregulation of brain systems which progressively increase over time
This results in compulsive drug use and loss of control

Question 2

What promotes the chronic deviation of a reward set point?

Answer 2

Dysregulation of the reward

Activation of brain hormonal stress responses

Question 3

What are the three stages of the addiction cycle?

Answer 3

Binge-intoxication
Wtihdrawal-negative affect
Preoccupation-anticipation

Koob 1997

Question 4

Describe allostasis

Answer 4

Systems have set external limits which allow them to survive
Deviations are correct by local negative feedbacks
Long term, the parameters of the whole system change to meet the chronic demands

Question 5

Define an allostatic state

Answer 5

Chronic deviation of regulatory systems from their normal state of operation with the establishment of a new set point

Question 6

What is the relationship between amount of stress hormones and drug consumption

Answer 6

More stress > more drug

Question 7

Outline the cascade of events that promote substance misuse in addiction

Answer 7

Reward system activated in binge
Causes allostatic down reg of DA and opioid at end of binge
So less positive reinforcers for day-to-day activities

HPA and CRF activation during acute withdrawal persists into abstinence
So more negative reinforcers to provide motivation to take substance

Question 8

What is sensitisation?

Answer 8

Increased response to same amount of substance

Occurs with intermittent exposure to substance