Biological Explanations of Addiction Flashcards
Addiction
When people become physically dependent on a substance through repeated use.
The role of dopamine in addiction (example with cigarretes)
Dopamine and the brain’s reward pathway plays a critical role in addiction. Nicotine binds to receptors in a region of the brain called the VTA, which then triggers the release of dopamine in the nucleus accumbens, resulting in pleasure and positive reinforcement of the activity.
Kendler & Prescott 1998
Aim: Understand if genetic factors play a role in the progression from drug use to dependence by examining patterns of cocaine and marijuana use.
Sample:
1,934 twins ranging in age from 22 to 62.
Research Method:
Twin study
Procedure:
The researchers telephone interviewed the twins independently to determine if they had ever used the aforementioned drugs or became dependent on them before. Drug “use” was defined as at least one non-prescribed use of a drug and “dependence” was based on having physical withdrawal symptoms or taken larger amounts of the drug than needed.
Findings:
Family and social environmental factors are influential in determining whether an individual starts using drugs, but the progression from the use of cocaine or marijuana to dependence is due largely to genetic factors; The concordance rate for MZ twins were higher than DZ twins (e.g. for cocaine use MZ = 35 percent and DZ = 0 percent).
How is a genetic argument for the origin of addiction built with twin studies?
If addiction has a genetic component, then monozygotic twins should have a higher concordance rate of addictive behavior compared to dizygotic twins.
DRD2 Gene what is it responsible for how is it linked to addiction?
One of the genes that researchers are focused on about addiction is the DRD2 gene. It is linked because it codes for the number of dopamine receptors available in the brain’s reward system. Therefore, a person with fewer dopamine receptors is less sensitive to the effect of dopamine compared to someone with more dopamine receptors, so therefore need higher levels of dopamine to feel the same amount of stimulation. People with the DRD2 A1 variation of the gene have fewer dopamine receptors and seem more vulnerable to addictions.
Ponce et al (2008)
Aim: Determine whether the presence of the DRD21 A1 allele was correlated to prevalence of alcoholism abuse and alcoholism in family history.
Research method:
Correlational
Sample:
103 alcohol-dependent males
Procedure:
Genetic analysis was performed on participants
Findings:
39% of participants carried the DRD2 A1 allele, and the higher prevalence of alcoholism in the family and an early onset of alcohol abuse.
Evaluation point about addiction research results
The results of addiction research are inconsistent - a low level of reliability. For instance, different drugs seem to have different levels of concordance in twins. It leads to confusion and the question: Is this the nature of the drugs, or does this have something to do with the way that the genes work?
Evaluation point about addiction regarding a specific type of validity.
There are questions about construct validity, specifically about operationalizing constructs such as “addiction” and “dependence”.
Evaluation point about the nature of the genetic argument
The genetic argument is both reductionist and deterministic. Although a genetic factor may have to interact with the environment to produce addictive behavior, the argument still posits that if an individual has the correct set of genes, then he is more likely to be addicted to the substance.
