Biological Models of Addiction
MODEL ONE: GENETICS
McGue (1999) found that genes contribute to the development of alcohol dependence, with heritability estimates from 50-60% for both men and women. Noble et al (1991) found that the A1 variant of the DRD2 (Dopamine Receptor) was present in more than 2/3 of deceased alcoholics. Those with the A1 variant appear to have fewer dopamine receptors; they then turn to drugs and alcohol to increase their dopamine levels – compensating for the deficiency.
|Evaluation of Genetics | |Strengths |Limitations | |Explains why some individuals are more resistant to treatment and more likely|Caine et al (2007) found that mice engineered to lack the brain receptor (D1), | |to relapse. |did not develop a taste for cocaine when it was presented to them. Other | |Synoptic; Psychology is a science. |‘normal’ mice did however continue to take the drug. | | |Synoptic; Deterministic, Reductionist, Ethics of using animals in research | | |(above), and Ethics of using deceased individuals. |
MODEL TWO: THE ROLE OF DOPAMINE (THE DISEASE MODEL)
Initiation – Rewarding experiences (e.g. drug taking) trigger the release of dopamine, telling the brain to do it again. Maintenance – Chronic exposure to alcohol/drugs result in a reduction in the activity of these positive reward circuits (down regulation), this causes withdrawal symptoms (+ anxiety). Koob and Kreek (2001) found that as a result of down regulation, the drug levels that are needed to trigger the reward systems increase. Relapse – Addicts have learned to expect a reward from the drug, and this is reinforced again through social cues. An addict’s capacity for self control is also weakened, as the frontal cortex has become less effective at making decisions and judging consequences.
|Evaluation of The Role of Dopamine (The Disease Model) | |Strengths |Limitations | |Volkow et al (2001) gave Ritalin (increases dopamine levels) to volunteers. |Volkow et al (2003) claimed people who grow up in a positive and engaging | |Brain scans show that those who liked the drug had fewer dopamine receptors. |surrounding are protected against addiction – even if they don’t have a | |Those who had normal levels couldn’t withstand the additional rush. |responsive dopamine system. They get excited by natural stimuli, reducing their | | |desire for an artificial boost. | |Synoptic; Psychology is a science. | | | |Synoptic; Deterministic, Reductionist. |
Cognitive Models of Addiction
MODEL ONE: THE SELF-MEDICATION MODEL
Initiation – Individuals think that the drug is helping with their current problems. Research indicates that these drugs are specifically chosen for their effects (e.g. alcohol reduces...