Biological Risk Factors (AQA A Level Psychology): Revision Note

Genetic vulnerability as a risk factor

• Genetic vulnerability is the idea that inherited characteristics passed on from parents to children increase the likelihood that someone will develop an addiction

  • What is inherited is not an addiction itself but a predisposition or vulnerability to drug dependence, as genes are not inevitable causes of addiction on their own

• Research into genetic vulnerability to addiction analyses the genetic structure of the individual and compares DNA sequences of family members to identify genes involved in addiction to a particular substance or behaviour

• Much research into genetic vulnerability has focused on twin studies and family linkage studies

• As MZ twins share 100% of their genetic make-up while DZ twins share only 50%, it allows psychologists to make useful comparisons regarding genetic vulnerability to addiction, measuring the concordance rate

• The likelihood of someone becoming a smoker, gambler or alcohol-dependent is viewed in terms of increased risk if a parent or MZ twin engages in these behaviours

Research which investigates genetic vulnerability as a risk factor

• Kendler et al. (2012) used data from the National Swedish Adoption Study, looking at children adopted away as children from biological families in which at least one parent had an addiction

  • They found the children had a significantly greater risk of developing an addiction themselves (8.6%) compared with adopted away individuals with no addicted parent in their biological family (4.2%)

• Slutske et al. (2010) found that MZ twins had a higher concordance rate for a gambling disorder (49% for male pairs and 55% for female pairs) in comparison to DZ twins (21% for male and female pairs), suggesting genetic vulnerability was partly responsible

Evaluation of genetic vulnerability as a risk factor

Strengths

• Pianezza et al. (1998) found that some people lack a fully functioning enzyme responsible for metabolising nicotine, and these individuals smoke significantly less than those with the fully functioning version

  • As expression of this enzyme is genetically determined, individuals with the fully functioning enzyme are at greater genetic risk of nicotine addiction

• Some research suggests that inherited personality traits may be responsible for addiction, with novelty-seeking being positively correlated with genetic markers for the D4 dopamine receptor and also with addiction to alcohol, which broadens the support for genetic vulnerability (Ray et al, 2009) 

Limitations

• Monozygotic (MZ) twins are more likely to be treated similarly by parents than dizygotic twins, meaning that concordance rate differences may be the result of upbringing rather than genetic similarity, weakening the argument for a genetic vulnerability to addiction

• There are many other factors which affect the predisposition to addiction, such as exposure to the drug, availability, stress, family influence and peers, so genetic vulnerability remains an incomplete explanation

Issues & Debates

• Suggesting that addiction is genetically determined supports a biological determinism stance, implying individuals have limited control over addictive behaviours

  • This undermines the role of personal choice or free will, raising ethical concerns, especially around blame or responsibility in addiction

• Genetic vulnerability research is biologically reductionist, focusing on genes and neurotransmitters while ignoring psychological, social or cognitive factors

  • A more holistic approach would consider how biology interacts with the environment and personality in the development of addiction, providing a more complete explanation of addiction