Biological Explanations of Addiction

Question 1

What does the disease model of addiction argue?

Answer 1

It argues that addiction has biological roots and is a problem with which the individual will struggle throughout their life.

Question 2

How do drugs generally make people feel good and want to do a drug again (in terms of the brain’s reward pathway)?

Answer 2

1. The drugs bind to receptors on neurons in the VTA (Ventral tegmental area), stimulating the neurons
2. This stimulation of VTA neurons releases a surge of dopamine in the nucleus accumbens (the brain’s reward system).
3. This dopamine release creates feelings of pleasure and reward, positively reinforcing using the drug in the nucleus accumbens
4. Glutamate, an excitatory neurotransmitter, may also be released which appears to link the substance to the feelings of pleasure, positively reinforcing taking the drug again

Question 3

How may a drug act as an agonist for a neurotransmitter?

Answer 3

The drug may bind to a receptor site on a post-synaptic neuron, causing dopamine neurons to fire.

Question 4

What does genetic vulnerability in addiction argue? and what is its two methods of figuring out this?

Answer 4

If addiction has a genetic component, we should see addictive behaviors running within families, or in case of twins, monozygotic twins should have a higher rate of both of them having an addictive behavior than dizygotic twins.

• Family studies
• Twin studies

Question 5

Kendler and Prescot (1998) Twin study

Answer 5

Participants:

Study involved 1,934 female twins, aged 22 to 62.
Participants included both identical and fraternal twins.

Definitions:

Drug use: At least one instance of non-prescribed drug use.
Drug dependence: Based on DSM-IV criteria, including:
Tolerance or withdrawal.
Using larger amounts or for a longer time than intended.
Spending significant time seeking, using, or recovering from drug effects.

Key Findings:

Family and social environments significantly influenced whether an individual began using drugs.

Progression from drug use to dependence was primarily influenced by genetic factors.

Higher concordance rates for identical twins than fraternal twins

Cocaine dependence: 35% for identical twins, 0% for fraternal twins.

Conclusion:

Drug use initiation is shaped by environmental factors, while genetic predisposition plays a major role in the transition from use to dependence.

Question 6

What is the gene that researchers focus on for addiction? and why?

Answer 6

DRD2 Gene

This codes for the number of dopamine receptors available in the brain’s reward system. Therefore, a person with few dopamine receptors will need higher levels of dopamine to produce the same pleasure effects compared to a person with more dopamine receptors.

Question 7

Which variation of DRD2 gene do people who are more vulnerable to addiction have?

Answer 7

DRD2 A1 allele

(Codes for fewer dopamine receptors)

Question 8

Evaluation of biological explanations for addiction

Answer 8

• Most of it is animal research making the generalizing of findings to humans questionable
• The results of addiction research are inconsistent, does not have a high level of reliability. E.g. (different levels of concordance rate for different drugs)
• Construct validity. Are we measuring what made someone try a drug, or the level of addiction. Difficult to separate between them.
• A genetic argument is reductionist and deterministic.