GENETICS AO1

• Biological explanation of addictive behaviour

  The role of genetics
• This approach is particularly useful in explaining why, although many people engage in behaviours that may be addictive, not all become addicted
• Genes may affect how people respond when they try the behaviour in the first place
• DRD2 gene


  A dopamine gene, individuals with the A1 variant have fewer dopamine receptors (D2)
• Having fewer dopamine receptors (D2)

  Less pleasure is experienced in the nucleus accumbens when taking part in activities, so the addict has to overcompensate in order to gain satisfaction
• Comings et al (1996) study on smokers and ex-smokers

  • 48.7% carried the A1 variant of the DRD2 gene compared with 25.9% of the general population
• Comings et al (1996) study on gamblers

  • 50.9% of gamblers carried the A1 variant of the DRD2 gene in comparison with 25.9% of non-addicts
• ADH and ALDH genes


  Responsible for the process of how alcohol is metabolised by the body
• Alcohol metabolism


  1. Alcohol is broken down into acetaldehyde by alcohol dehydrogenase (ADH)

  2. Acetaldehyde is broken down further into acetic acid and water by acetaldehyde dehydrogenase (ALDH)
• Variations of the ADH genes have been linked to increased risk of alcoholism
• Lower activity variants of ADH genes

  Associated with an increased risk of alcohol dependence in East Asian populations