Data and Design: Advancing Theory for Complex Adaptive Systems

Complex adaptive systems exhibit certain types of behaviour that are difficult to predict or understand using reductionist approaches, such as linearization or assuming conditions of optimality. This research focuses on the complex adaptive systems associated with public health. These are noted for being driven by many latent forces, shaped centrally by human behaviour. Dynamic simulation techniques, including agent-based models (ABMs) and system dynamics (SD) models, have been used to study the behaviour of complex adaptive systems, including in public health. While much has been learned, such work is still hampered by important limitations. Models of complex systems themselves can be quite complex, increasing the difficulty in explaining unexpected model behaviour, whether that behaviour comes from model code errors or is due to new learning. Model complexity also leads to model designs that are hard to adapt to growing knowledge about the subject area, further reducing model-generated insights. In the current literature of dynamic simulations of human public health behaviour, few focus on capturing explicit psychological theories of human behaviour. Given that human behaviour, especially health and risk behaviour, is so central to understanding of processes in public health, this work explores several methods to improve the utility and flexibility of dynamic models in public health. This work is undertaken in three projects. The first uses a machine learning algorithm, the particle filter, to augment a simple ABM in the presence of continuous disease prevalence data from the modelled system. It is shown that, while using the particle filter improves the accuracy of the ABM, when compared with previous work using SD with a particle filter, the ABM has some limitations, which are discussed. The second presents a model design pattern that focuses on scalability and modularity to improve the development time, testability, and flexibility of a dynamic simulation for tobacco smoking. This method also supports a general pattern of constructing hybrid models --- those that contain elements of multiple methods, such as agent-based or system dynamics. This method is demonstrated with a stylized example of tobacco smoking in a human population. The final line of work implements this modular design pattern, with differing mechanisms of addiction dynamics, within a rich behavioural model of tobacco purchasing and consumption. It integrates the results from a discrete choice experiment, which is a widely used economic method for study human preferences. It compares and contrasts four independent addiction modules under different population assumptions. A number of important insights are discussed: no single module was universally more accurate across all human subpopulations, demonstrating the benefit of exploring a diversity of approaches; increasing the number of parameters does not necessarily improve a module's predictions, since the overall least accurate module had the second highest number of parameters; and slight changes in module structure can lead to drastic improvements, implying the need to be able to iteratively learn from model behaviour

Tobacco use and cessation: What matters to Southeast Alaska Native young adults?

Thesis (Ph.D.) University of Alaska Fairbanks, 2013Background: The smoking rate among young Alaska Native adults (ages 19-29) in Southeast Alaska is 70% as compared to the statewide adult smoking rate of 21%, the Alaska Native adult rate of 41%, and the overall young adult rate of 32%. Southeast Alaska Regional Health Consortium (SEARHC), the non-profit tribal health consortium serving Southeast Alaska, commissioned this research to inform development of a young adult-specific, social marketing-based smoking cessation intervention. Methods: Using purposive sampling, 23 individuals were recruited for five focus groups and four individual interviews in Juneau, Alaska. Following a social marketing framework, the research assessed participant beliefs about the benefits and negative impacts of smoking, barriers to quitting, and preferred quit support methods, as well as participant reactions to particular anti-smoking advertisements and quit support methods. Results: Almost all participants reported an interest in quitting smoking. Stress relief, boredom relief, relaxation, and oral satisfaction were the main benefits of smoking. Downsides to smoking included negative short-term health impacts, negative impacts on children in the extended family, and negative cosmetic impacts. Barriers to quitting included loss of listed benefits, addiction and habit, fatalism, and the high prevalence of smoking among family and friends. The preferred method of quitting was cold turkey (unassisted quitting), with very few participants reporting use of counseling or pharmacotherapy. Participants preferred high emotional level anti-smoking advertisements with either strongly negative emotional valence (e.g., fear and disgust) or strongly positive emotional valence (e.g., joy, happiness). Reaction to quit support methods was most favorable to texting support and a smart phone app, and most negative toward a smart phone video game. Reaction to counseling was strongly supportive among those who had tried it and largely but not totally negative among those who had not. Conclusion: Young Alaska Native adults in Juneau who smoke are interested in quitting but prefer cold turkey to counseling and pharmacotherapy. They are more concerned about short-term than long-term health impacts, and they are sensitive to the impact of smoking on their appearance and on children in their extended family. Findings formed a foundation for a proposed social-marketing based intervention

Addiction is driven by excessive goal-directed drug choice under negative affect: Translational critique of habit and compulsion theory

This is the final version. Available on open access from Springer Nature via the DOI in this recordDrug addiction may be a goal-directed choice driven by excessive drug value in negative affective states, a habit driven by strong stimulus-response associations, or a compulsion driven by insensitivity to costs imposed on drug seeking. Laboratory animal and human evidence for these three theories is evaluated. Excessive goal theory is supported by dependence severity being associated with greater drug choice/economic demand. Drug choice is demonstrably goal-directed (driven by the expected value of the drug) and can be augmented by stress/negative mood induction and withdrawal – effects amplified in those with psychiatric symptoms and drug use coping motives. Furthermore, psychiatric symptoms confer risk of dependence, and coping motives mediate this risk. Habit theory of addiction has weaker support. Habitual behaviour seen in drug exposed animals often does not occur in complex decision scenarios, or where responding is rewarded, so habit is unlikely to explain most human addictive behaviour where these conditions apply. Furthermore, most human studies have not found greater propensity to habitual behaviour in drug users or as a function of dependence severity, and the minority that have can be explained by task disengagement producing impaired explicit contingency knowledge. Compulsion theory of addiction also has weak support. The persistence of punished drug seeking in animals is better explained by greater drug value (evinced by the association with economic demand) than by insensitivity to costs. Furthermore, human studies have provided weak evidence that propensity discount cost imposed on drug seeking is associated with dependence severity. These data suggest that human addiction is primarily driven by excessive goal-directed drug choice under negative affect, and less by habit or compulsion. Addiction is pathological because negative states powerfully increase expected drug value acutely outweighing abstinence goals.Alcohol Research UKMedical Research Council (MRC

Age and Impulsive Behavior in Drug Addiction: A Review of Past Research and Future

Impulsive behavior is implicated in the initiation, maintenance, and relapse of drug-seeking behaviors involved in drug addiction. Research shows that changes in impulsive behavior across the lifespan contribute to drug use and addiction. The goal of this review is to examine existing research on the relationship between impulsive behavior and drug use across the lifespan and to recommend directions for future research. Three domains of impulsive behavior are explored in this review: impulsive behavior-related personality traits, delay discounting, and prepotent response inhibition. First, we present previous research on these three domains of impulsive behavior and drug use across developmental stages. Then, we discuss how changes in impulsive behavior across the lifespan are implicated in the progression of drug use and addiction. Finally, we discuss the relatively limited attention given to middle-to-older adults in the current literature, consider the validity of the measures used to assess impulsive behavior in middle-to-older adulthood, and suggest recommendations for future research

Healthy snacks consumption and the Theory of Planned Behaviour. The role of anticipated regret

Two empirical studies explored the role of anticipated regret (AR) within the Theory of Planned Behavior (TPB) framework (Ajzen, 1991), applied to the case of healthy snacks consumption. AR captures affective reactions and it can be defined as an unpleasant emotion experienced when people realize or imagine that the present situation would be better if they had made a different decision. In this research AR refers to the expected negative feelings for not having consumed healthy snacks (i.e., inaction regret). The aims were: a) to test whether AR improves the TPB predictive power; b) to analyze whether it acts as moderator within the TPB model relationships. Two longitudinal studies were conducted. Target behaviors were: consumption of fruit and vegetables as snacks (Study 1); consumption of fruit as snacks (Study 2). At time 1, the questionnaire included measures of intention and its antecedents, according to the TPB. Both the affective and evaluative components of attitude were assessed. At time 2, self-reported consumption behaviors were surveyed. Two convenience samples of Italian adults were recruited. In hierarchical regressions, the TPB variables were added at the first step; AR was added at the second step, and the interactions at the last step. Results showed that AR significantly improved the TPB ability to predict both intentions and behaviours, also after controlling for intention. In both studies AR moderated the effect of affective attitude on intention: affective attitude was significant only for people low in AR

Lung cancer screening participation: attitudinal, socioeconomic and smoking-related factors

Socioeconomic and smoking-related biases in participation threaten the equity and effectiveness of any future UK lung cancer screening programme. This thesis used a mixed methods approach to investigate psychosocial and cognitive factors that might contribute to these biases, with the aim of identifying possible targets for intervention in screening communication strategies. This informed the design of screening invitation materials aimed at engaging low socioeconomic position (SEP) smokers with a screening offer, which were tested using a randomised controlled pilot trial. The findings of these studies suggest that the introduction of a lung cancer screening programme would be acceptable to older English adults. However, while there was high willingness to be screened (>91%), this was not matched by high uptake of screening in the pilot trial (55%). Chapters 4 to 7 showed that negative beliefs about outcomes and early detection for lung cancer were prevalent among participants recruited from low SEP communities, and associated with current smoking status. Compared with their non-smoking counterparts, smokers more commonly expressed fatalistic beliefs about risk, survival and treatment for lung cancer (including early stage disease), worried about lung cancer and the outcome of screening, and perceived smoking and lung cancer to be stigmatised. Intervention screening invitation materials were designed to improve uptake by minimising these factors but an early interim analysis of the pilot trial testing these materials showed no effect on uptake of lung cancer screening appointments (n=241; final target N=2000). Lower SEP smokers’ more negative expectations of risk, stigma, treatment and outcomes for lung cancer, particularly for older high risk adults, appear to undermine the salience and perceived personal benefit of lung cancer screening. Further work needs to be done to explore whether interventions can effectively modify these perceptions to improve engagement with screening among the very group most likely to benefit