Specific genes have been identified as increasing an individuals vulnerability to addiction. But some genes decrease vulnerability.
D2 Receptors
-involved with dopamine in the brain, feelings of reward
-Addicts have been found to have low numbers of D2 receptors.
-Fewer receptors means less dopamine activity.
CYP2A6nicotine enzyme
-it metabolises nicotine, expression of this enzyme is genetically determined.
-Pianezza et al found that some people lack a fully functioning CYP2A6 enzyme.
-Those that have the fully functioning enzyme, smoke more as metabolises nicotine quicker so leaves the body quicker and then craves more nicotine.
Support from adoption studies
-Kendler et al carried out the national Swedish adoption study. They looked at adults who had been adopted from families who had at least on parent who had an addiction. They found these children later had a greater chance of developing an addiction, compared to adopted children with nobiologically addicted family members.
Support from twin studies
Kendler and Prrescott compared concordance rates of drug abuse amongst 2000 set of Mz and Dz twins. Drug abuse found concordance rates for Mz twins higher than Dz twins.
It suggests drug abuse and dependency are determined genetically. It is generalisable as the sample size is big so more representative of population.
Genetically vulnerable considered biologically deterministic
refers to the idea that all human behaviour is innate and determind my genes, can be hereditary, controls behaviour and underestimates other factors.
