The Biological Approach
Initation - A01
- Addicts inherit a genetic predisposition to developing an addiction.
- Multiple genes are responsible for addictive behaviour.
- Researchers have focused on the A1 variant of the DRD2 gene - involved in regulation of dopamine levels. This gene may increase people's sensitivity to the action of dopamine.
- More recently researchers have identified specific genes e.g. SLC6A3-9 (responsible for removing dopamine from the synapse) which may also be involved in addiction.
Maintenance - A01
- The meso-limbic dopamine system - concerned with memory, reward + motivational processes - is involved with the maintenance of addictive behaviour.
- Cells in the meso-limbic dopamine system release small amounts of dopamine into the synapse.
- Addictive substances + behaviours increase dopamine levels in the synapse.
- Addicts continue with their behaviour in order to experience the highs from their addiction, they need to maintain increasingly high levels of dopamine. Falling levels can lead to unpleasant withdrawal symptoms.
- People who are more susceptible to addictions may have inherited a more sensitive meso-limblic dopamine system.
Relapse - A01
- Substances such as nicotine activate the dopamine reward pathway + the brain adapts to be in balance when the substance is present (neuroadaptation).
- When the substance is discontinued the adaptation is no longer needed + is experienced as withdrawal symptoms which are unpleasant + immediately relieved by using the substance.
Application to Smoking
Initiation - A02
Meta-analysis by THORGEIRSSON ET AL (2008)…