Drug dependance Lecture 15

Question 1

Definition of dependance

Answer 1

State of needing or depending on something to function or survive .
Refers to both physical and physiological characteristics
Drugs can be abused/misused.

Question 2

How do drugs affect the mesolimbocortical pathway?

Answer 2

• Any drug that interferes with dopamine transmission interferes with this pathway
• Cocaine acts directly at the synapse
• Heroin can interact with cell bodies in the VTA, indirectly affecting the dopamine pathway
• > Leads to less electrically active cellls
• > these cells release GABA, so the “brake” is released so GABA levels decrease
• > This increases activity of dopamine releasing cells

Question 3

What three things change with chronic use of a drug?

Answer 3

Tolerance:
Decreased effect with continued use due to
-Receptor desensitisation
-Drug metabolism

Physiological Dependence:
Withdrawal symptoms
-Short term e.g. pain hypersensitivity on opiods
-Adaptive processes -> over compensation in drug absence

Psychological Dependence
-Craving/Compulsion - impaired decision making
Can be long term

All lead to dependance

Question 4

Why are some drugs more likely to cause dependence than others?

Answer 4

• Level/speed of dopamine release
• Severity of withdrawal symptoms
• Route of administration

Question 5

Treatment of dependance

Answer 5

Detoxification - withdrawal
Dose is reduced over time
Use agents with different pharmacokinetics - but has same effect
High chances of relapse, timing of intervention is critical
If changes to the CNS has occurred, its hard to treat whilst if changes haven’t happened, its easier to treat and not relapse.