EBQ-AP Psychology Addiction

Introduction: Addiction is a complex disease characterized by compulsive drug seeking and use despite negative consequences. While environmental factors play a role, there is growing evidence that genetics also contribute to susceptibility to addiction. This question will explore research investigating the link between genes and addiction.
Source 1: Twin Study (Kendler et al., 2000)
Participants: 1,587 pairs of twins (both identical and fraternal) from the Virginia Twin Registry.
Methodology: Researchers assessed participants for lifetime diagnoses of substance use disorders using standardized clinical interviews. They compared the concordance rates (the likelihood of both twins having the disorder) for identical twins, who share all their genes, and fraternal twins, who share only half their genes.
Results: The concordance rate for substance use disorders was significantly higher for identical twins (55%) compared to fraternal twins (31%). This suggests a significant genetic influence on addiction vulnerability.
Discussion: The higher concordance rate in identical twins compared to fraternal twins indicates that genes play a role in addiction. However, the fact that the rate isn't 100% for identical twins suggests that environmental factors also interact with genes to influence addiction risk.
Source 2: Gene Association Study (Comings et al., 1996)
Participants: Over 400 individuals diagnosed with alcoholism and a control group without alcoholism.
Methodology: Researchers examined a specific gene, the dopamine D2 receptor gene (DRD2), which is involved in the brain's reward system. They looked for variations (alleles) in this gene that might be associated with alcoholism.
Results: The study found a higher prevalence of a specific DRD2 allele in individuals with alcoholism compared to the control group. This suggests a possible link between this gene variation and increased risk for alcoholism.
Discussion: While this study identifies a potential genetic link to alcoholism, it doesn't prove causation. The specific DRD2 allele might not directly cause alcoholism but could be a marker for another gene or environmental factor that contributes to the risk.
Source 3: Gene-Environment Interaction Study (Caspi et al., 2002)
Participants: Over 1,000 individuals born in Dunedin, New Zealand, followed from birth to adulthood.
Methodology: Researchers assessed participants for a specific variation in the serotonin transporter gene (5-HTT) and for experiences of childhood maltreatment. They then examined how these factors interacted to influence the development of depression, which is often comorbid with addiction.
Results: The study found that individuals with a specific variation of the 5-HTT gene were more likely to develop depression only if they had also experienced childhood maltreatment. This suggests that genes and environment interact to influence risk for mental health problems like depression, which could indirectly influence addiction vulnerability.
Discussion: This study highlights the importance of gene-environment interactions in addiction. Even if someone has a genetic predisposition, environmental factors like childhood maltreatment can significantly increase their risk.

Using the sources provided, develop and justify an argument about the connection between genetics and addiction.
A.  Propose a specific and defensible claim based in psychological science that
responds to the question.
B. (i) Support your claim using at least one piece of specific and relevant
evidence from one of the sources.
(ii) Explain how the evidence from Part B (i) supports your claim using a
psychological perspective, theory, concept, or research finding learned
in AP Psychology.
C. (i) Support your claim using an additional piece of specific and relevant
evidence from a different source than the one that was used in
Part B (i).
(ii) Explain how the evidence from Part C (i) supports your claim using a
different psychological perspective, theory, concept, or research finding
learned in AP Psychology than the one that was used in
Part B (ii).