Genetic testing for complex disease susceptibility : psychological issues
The aim of this research was to provide empirical evidence on psychological issues relevant to the potential clinical utility of genetic tests for susceptibility to complex diseases. The results of such tests could increase motivation to change health behaviours but could also be misinterpreted, causing psychological distress on the one hand, and complacency on the other. The research comprised three studies which addressed: public interest in genetic testing the psychological impact of genetic testing and the impact of genetic testing on health behaviours. Study 1 (n= 1,960) utilised questions included in the Office for National Statistics omnibus survey to examine the level of public interest in taking genetic tests. Two thirds of respondents expressed interest in taking genetic tests for two complex diseases, cancer and heart disease, and there was greatest interest among people with intermediate levels of educational attainment. Study 2a-c (n= 1,024) was a postal questionnaire survey conducted in Oxfordshire, using a 2x2 (cancer vs heart disease x leaflet vs no leaflet) experimental design. Study 2a examined the effects of the leaflet on attitudes, and found that interest in genetic testing was higher amongst respondents who received the leaflet, as was subjective understanding of genetic testing. Study 2b provided support for the hypothesis that vulnerable people may self-select themselves out of genetic testing, by showing that anticipated reactions were associated with interest in genetic testing. Study 2c looked at responses amongst the smokers in the sample, and found that smokers who were more motivated to quit were more likely to be interested in genetic testing, and that smokers with lower understanding and educational attainment were more likely to believe that receiving a lower-risk genetic test result would make them feel that it would be safe for them to carry on smoking. The findings from these studies were used to feed into the design and interpretation of Study 3 (n=61), an exploratory study in which smokers were randomly allocated to receive genetic test results for a gene associated with lung cancer susceptibility (GSTM 1) or a control group, and followed up for two months. The results from Study 3 suggested that the process of genetic testing could increase motivation to quit smoking, but that the genetic test result itself may have relatively little impact. It is hoped that this research contributes to the current debate about how the clinical utility of emergent genetic tests for susceptibility to complex diseases might be evaluated in future research.