Factors influencing dependence-liability

Question 1

What are the factors that influence dependence liability?

Answer 1

There are a variety of factors influencing drug dependence-liability of an individual and therefore persistent drug use.

Include:

• Genetic predisposition
• Type of drug and its effects
• Conditioned cues

Question 2

What are genetic factors?

Answer 2

Individual differences in susceptibility to dependence suggest some predisposition, possibly genetic.

Question 3

Give examples of genetic factors?

Answer 3

Personality traits:

• Addictive personality
• Impulsiveness - compared to non-users, drug abusers have higher impulsivity scores in the Eysenck personality inventory questionnaire (King et al 1990).

Question 4

What is pharmacokinetics?

Answer 4

Sometimes referred to as what the body does to the drug, refers to the movement of drug into, through and out of the body.

Question 5

What are the pharmacokinetic factors that can lead to dependence/persistent use?

Answer 5

• Rate of onset
• Duration of action
• Dose
• Rate of elimination

Question 6

How does rate of elimination affect dependence-liability?

Answer 6

Drugs which reach CNS rapidly are the most reinforcing and hence route of administration is important in drug dependence.

For example, crack cocaine is more lipid soluble than normal cocaine so enter the brain quicker. It has a higher dependence liability. Whereas drugs taken orally have a lower liability.

Question 7

How does duration of action affect dependence-liability?

Answer 7

Dependence liability is determined partly by the period for which the drug is active in the brain. There is probably an optimum time. Short-life less likely, long life (barbituates) more likely.

Question 8

How does dose affect dependence liability?

Answer 8

Increases as level of intoxication increases.

Tolerance - the need for progressively higher doses of drug to reinstate the effect experience the first time it was used.

Question 9

How does rate of elimination affect dependence liability?

Answer 9

Withdrawal syndrome (physical dependence) is most severe for drugs which are eliminated rapidly. This indicates that rate of change of activation or inhibition is an important  factor in determining drug dependence. 
- Replace heroin with 0.5h half life with methodon (15-40h) for rehabilitation

Question 10

What are conditioned cues?

Answer 10

Associations with drug intake can become potent conditioned cues, thereby promoting continued intake.

Question 11

What can these cues be?

Answer 11

• Effect on mood/behaviour
• Place
• Tolerance

Question 12

Give an example of conditioned cues leading to dependence liability?

Answer 12

Recovering addicts, e.g. alcholic entering place where they use to drink such as pub are more likely to relapse.

Question 13

Give an example of how conditioned cues may be good?

Answer 13

Vietnam soldiers took opiates while on service but when they returned they did not display drug-seeking behaviour. This is conversley to heroin addicts in which 80% of sobering heroin addicts still have issues in normal society.

Question 14

How long can conditioned cues last?

Answer 14

Conditioned environmental cues remain potent stimuli, reinforcing drug intake, for months after cessation of drug administration leading to inability to give up causing persistent use.