genes - 5 marks

• DRD2

  some alleles of this gene predispose someone to addiction

  responsible for D2 dop receptors in brain
• D2A1 - variation of DRD2 linked to AB

  results > fewer D2 receptors in NA > don't experience as much pleasure from rewarding activities

  try and overcompensate by engaging more excessively to overstimulate receptors
• D2A1 STUDY - Comings et al (96)

  48.7% smokers carry gene, compared to 25.9% of non

  50.9% of gamblers carry gene, compared to 25.9% of non
• ADH / ALDH } genes and alcohol

  alcohol dehydrogenase and aldehyde dehydrogenase

  helps body metabolise alcohol

  ADH enzyme breaks down alc > acetaldehyde } ALDH breaks that down > acetic water and acid

  certain variants - influence likelihood of alc A and consumption

  ADH1B variant > significant high risk for alcoholism - bc - no acetaldehyde build up is associated with it > drink without effects (potential to become addicted to it)
• ADH / ALDH STUDY - Tolstrup et al (07)

  9080 men and women with ADH1B - drank more alc and had higher risk for alc, heavy drinking and everyday drinking

  presence of variant - linked with high risk for heavy drinking and alc among white population (62%) and east asian population (24%)