Karteikarten
Addiction 2
Karten in diesem Stapel (17)
- 1How should and how shouldn't causes of addiction be thought of? (LO3)- No single cause of addiction
- Can think of contributory causes, which are neither necessary or sufficient but are events which increase the probability of developing an addiction - 2What have twin and adoption studies suggested about the heritability of substance use disorders? (LO3)Twin and adoption studies have both indicated a substantial role for genetics factors in the aetiology of addiction disorders.
For example, Agrawal and Lynskey (2008) estimated that between 30%-70% of influences on drug dependence are genetic.
Moreover, substantial genetic influence has been indicated across multiple different types of addiction with the lowest estimates ranging between 30% (for nicotine dependence) and 90% (for illicit drug dependence) (Slutske et al, 2010, Agrawal and Lynskey, 2008). - 3What are the limitations of twin and adoption studies (LO3)They, like the above studies, cannot indicate which specific genes are involved in addictions.
- 4What have the outcome of GWASs been? (LO3)Genome wide association studies have identified a number genetic variants associated with multiple different types of addiction disorders but mainly substance use disorders such as alcohol, nicotine or cannabis dependence.
For example, gene variants linked to the encoding of fatty acids and function of the dopaminergic system have been linked to cannabis abuse.
Therefore, these finding may help clarify by what mechanisms genetic influences contribute to addiction. - 5What are two issues with findings from GWASs? (LO3)Findings from GWAS have not been consistently replicated, suggesting that the results may not be reliable.
For example, a meta-analysis of two GWAS, in contrast to previous findings, found that no variant reached genome wide significance for cannabis use (Verweij et al)
Equally, when significance variants are found they typically account for less heritability (less than 2%: Agrawal et al, 2012) in addiction related phenotypes than you'd expect given the substantial estimates from twin and adoption studies. - 6What is a possible explanation for GWAS issues? (LO3)Nevertheless, it may be that influence of single variants on addiction phenotypes could be small and there is a polygenic effect where multiple genes of small effect size account for the overall heritability of addiction phenotypes as opposed to a large effect of single variants.
This would account for why the hertibality for - 7What evidence is there to support poly genetic effects in addiction? (LO3)Studies investigating polygenic risk scores have suggested that its is possible to gain an estimate of risk for a disorder or trait based multiple genes identified in previous research.
However, more work of this types is needed. - 8What has research suggested about the specificity of genetic influences on addiction phenotypes? (LO3)Multivariate twin designs (estimating the influence of additive genetic effects, shared and non shared environmental influences) have overall indicated that there is significant overlap in genetic influences on addictive phenotypes. In particular for alcohol, nicotine, and illicit drug dependencies (Agrawal et al, 2012)
This suggests common pathways in development of these phenotypes. - 9Why is genetic overlap surprising in some ways and what might account for it? (LO3)Given that different substances have very different pharmacologies and influence different neurological pathways, it is somewhat surprising that greater genetic specificity hasn't been found for substance use dependencies.
However, it may be that the high degree of comorbidity between substance use disorders could be amplifying genetic overlap and/or studies may lack the power to detect substance specific genetic influences (Agrawal et al, 2012) - 10If there is significant overlap in genetic influences, what might be contributing to the development of specific addiction phenotypes? (LO3)However, it may be that specific gene-environment interactions may be relevant to the development of particular addiction phenotypes;
In particular, it may be that the environment can influence how particular genes are expressed meaning that an individual could have variant that puts them at a general risk of developing an addiction and an environmental factor (such as use and exposure to a particular drug) could then make it more likely that which particular disorder is developed. - 11What is another possible gene environment interaction than the environment influencing how the genes are expressed? (LO3)Nevertheless, it may also be that environmental effects on individuals vary by genotype.
This means that a particular environmental factor may only lead to, or increase the likelihood, of the development of an addiction when a particular genetic variant is present in an individual. - 12What evidence is there supporting the role of g x e in addiction? (LO3)Daw et al (2014) found that individuals with a short allele of a particular gene had a significantly higher hazard of smoking initiation and regular smoking in environments where a higher proportion of neighbourhood peers smoked.
- 13What steps represent the transition from non-problem use to addiction? (LO3)-Opportunity for substance use
- First use
-Second use
-Regular use
- Development of an addiction
Therefore, explaining the progression from non-problem use to addiction likely involves multiple risks being relevant at different stages. - 14What was a key finding of Hines et al (2016) in relations to the transition from non-problem use to addiction? (LO3)In a cross-sectional study of 3824 Australian twins and siblings examining profession from cannabis use to dependence, Hines et al (2016) found that the influence of factors differs throughout the stages of drug use progression.
Two key implications for prevention. Firstly, as factors play different roles across drug involvement, interventions may benefit from tailoring to stages of drug use.
Secondly, targeting of interventions may improve by considering the consistency and differences in associated factors across the stages of drug use - 15From Hawkins et al (1992), outline some key environmental risk and protective factors that might for addictions (LO3)In a review of risk and protective factors for drug and substance use problems in adolescents and young adulthood Hawkins et al (1992) identified a range of key environmental factors:
Social and Environmental Factors:
- Social norms and availability of substances
- Association with drug using peers
- Peer rejection
Familial factors:
- drug behaviour, conflict, and low bonding
Individual Factors
- Personality (sensation seeking)
- Early onset of drug use
- Academic failure and low commitment to school - 16What are three issues to consider when thinking about the influence of environmental and social factors? (LO3)1. For the majority of psychological traits non-shared environments have typically been found to contribute more substantially to phenotypes than shared environments. Therefore, in the context of addictions environmental factors that are not shared by family members (i.e individual factors) are likely to be more influential.
2. Environmental factors are not likely to have a solitary influence but instead are likely to interact with genetic factors (see previous cards)
3. Different factors are likely to be have different influences at different stages of drug use progression (Hines et al, 2016) - 17What did Hines et al (2016) specifically find about the role of different contributory factors at different stages of use? (LO3)Factors associated with both speed of progression to opportunity and dependence were conduct disorder, parental drug problems, weekly tobacco use and female gender (protective)
Frequent childhood religious attendance (protective), parental conflict, parental alcohol problems and childhood sexual abuse were uniquely associated with transition to opportunity.
Depressive episode, tobacco dependence, alcohol dependence, other drug use and other drug dependence were uniquely associated with progression to dependence.
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- Choices Karteikarten am Addiction 2, erstellt von Nichola Livermore am 17/04/2017.
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- Nichola Livermore
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