Biological explanations of addiction
- Created by: stef16
- Created on: 08-02-16 14:28
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- Biological explanations of addiction
- Maintenance
- Receptors
- Withdrawal symptoms start to occur
- Become less sensitive
- Dysphoric state
- Down regulation
- Chronic overexposure to addictive substances eventually leads to a reduction in activity of positive circuits
- Actual drug taking increases
- Reinforcement
- Not for pleasure (positive reinforcement) anymore
- Maintained in order to avoid unpleasant state (negative reinforcement)
- Receptors
- Evaluation
- Social context
- People who lead stressful lives more prone to addiction
- Losing social status means a loss of DR2 receptors
- Reductionist
- Individual differences
- Shown by Ritalin study on children, Volkow et al.
- Shows importance of biological and physiological processes
- Addiction caused by malfunction of reward pathways - partly
- Nalextrone and sex addiction
- Stopped dopamine release, behaviour no longer gave reward so it went extinct
- Social context
- Genetics
- Kendler et al. - hereditability of nicotine addiction dependence - 60-70%
- DRD2
- Alcoholism
- A1 variant found in 2/3 deceased alcoholics, 1/5 of alcoholics had this variant
- Blum et al. - increased prevalence of A1 among children born to alcoholics - genetic link
- Smokers
- Men with A1 variant started smoking earlier and abstain for shorter periods
- 48.7.7% of smokers had A1 variant compared to 25.9% of non-smokers
- Alcoholism
- Initiation
- Range of pressures e.g. social, biological
- Positive reward pathway
- excitement of gambling can result in release of adrenaline, this energy boost can be addictive
- Genetics
- Those with D2A1 more likely to become gamblers
- Those with SLC6A3-9 gene less likely to smoke
- Disease model
- Addiction is an illness
- Treatment and prevention
- Emphasis on treatment
- Though it is irreversible due to brain chemistry changes
- Addiction is an illness
- Relapse
- Frontal cortex less effective at decision making
- Need for drug greater than anything else
- Brain tries to force behaviour due to lasting pleasure memories
- Addict that is abstaining constantly sees cues
- Constant reminder and stimulates dopamine in expectation of reward - even if it won't come
- Animal studies
- Mice lacking a particular receptor don't become cocaine addicts
- PET scans on primates exposed to amphetamines - reduced D2 density
- Monkey cocaine addiction - sub for less addictive substance which mimics. Effective. Replicated on humans
- Exercise in speculation? Hackman & Redelmeier
- Dopamine
- Mesolimbic dopamine system
- Spontaneous release of dopamine, maintaining regular mood
- Suggested people with more sensitive MDS are more susceptible to addiction. Liebman and Cooper
- Crack stimulates massive activation of the mesolimbic pathway
- Regulates mood and emotion. Heavily involved in motivation and reward processors
- Both alcohol and nicotine affect NS by increasing dopamine levels
- Incentive sensitisation theory
- Repeated exposure to drugs increases body's need for them
- Mesolimbic dopamine system
- Maintenance
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