Q10

• Dopamine theory


  A biological explanation of addictive behaviour
• Mesolimbic pathway


  1. Runs from the ventral tegmental area (VTA) to the nucleus accumbens (Nac)

  2. Crucial in addiction, often referred to as the reward pathway

  3. Activated by rewarding activities, releasing dopamine and creating pleasurable feelings that reinforce the behaviour

  4. Drugs, gambling, and gaming can also activate this pathway, generating pleasure and reinforcing these behaviours, which is central to addiction

  5. Over time, repeated behaviour increases the required level of the drug or activity to achieve the same reaction, contributing to the formation and escalation of addiction
• Addictive drugs can release two to ten times more dopamine than natural rewards, doing so more quickly and reliably
• This overwhelms brain receptors, leading the brain to produce less dopamine or eliminate dopamine receptors
• Research by Volkow et al. (1997) showed a reduction in both D2 receptors and dopamine release in cocaine users, linking dopamine to addiction
• As a result, dopamine's impact diminishes, and individuals need more of the substance to achieve the same pleasure, a phenomenon called 'tolerance' by Griffiths
• While dopamine and the reward pathway explain the appeal of addictive behaviours, more complex processes maintain addiction and cause relapse even after withdrawal symptoms disappear
• Addiction starts with the dopamine reward pathway but becomes entrenched due to changes in the frontal cortex
• Addictive behaviours alter brain circuits that determine attention, giving excessive importance (salience) to the behaviour and its cues
• The dopamine system drives the desire to engage in the behaviour, rather than enjoyment, explaining why addicts may no longer enjoy the behaviour but still crave it
• Genetics


  A second biological explanation of addictive behaviour
• The DRD2 gene, specifically the A1 variant, results in fewer dopamine receptors (D2) in individuals, leading to reduced pleasure in the nucleus accumbens during activities
• As a result, addicts must overcompensate to achieve satisfaction
• Comings et al. (1996) found that 48.7% of smokers and ex-smokers had the A1 variant, compared to 25.9% of the general population
• Similar findings were reported in gamblers, with 50.9% carrying the A1 variant compared to 25.9% of non-addicts
• The dopamine theory explains the maintenance of addiction and the effects of tolerance but doesn't address the initial cause of addictive behaviour
• While genetic factors can explain why some people become addicted and others don't, they don't provide a complete explanation
• A holistic approach, including environmental and social factors, is necessary to fully understand addiction