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Smoking is one of the leading causes of death in the world. About 80% of smokers start smoking before the age of 18. In the Appalachian area and the South in the United States, smoking percentages among adults and adolescents are higher than in other regions. Female smoking shows a variety of different trends from male smoking, and smoking brings particular health problems related to production to female smokers. These findings highlighted the importance of studying female teenage smokers in southwest Virginia. The initial project aimed to identify risk factors that might prevent smoking in an early stage. Dr. Helen Crawford led the Cognitive Neuroscience Lab at Virginia Tech in discovering the psychophysiological vulnerabilities of female teenage smokers. Toward this end, event-related potential (ERP), personality, and behavioral data were collected in teenage female smokers and non-smokers. These data were analyzed to examine possible psychophysiological vulnerabilities in female teenage smokers such as deficits in brain and cognitive function, personality traits, and environment influences. The purpose of this dissertation is to further analyze these data to elaborate and clarify the relationships among these vulnerabilities toward understanding teenage smoking behavior. Participants were 49 teenage girls (smokers and non-smokers) with age from 14 to 18. The measures included sensory gating, platelet MAO-B activity, attention, memory, temperament, schizotypal personality, recognition of facial expressions, taste and smell. The initial set of analyses compared smokers and non-smokers, including those classified as high and low dependent, on all dependent measures. The results suggested some psychophysiological vulnerabilities in female teenage smokers, which have been used as support for the self-medication and the orbito-frontal dysfunction models of why teenagers smoke (Crawford et al., 2004). Further examination of these factors may help teenagers to reduce the smoking dependency and possibly improve cognitive function. Specifically, this dissertation focused on the role of the variable of monoamine oxidase-B (MAO-B) in the correlations among sensory gating, MAO and other cognitive and personality measures. All smokers were divided into high and low MAO groups first. Comparison analyses were conducted between them. The high MAO group showed better sensory gating function than the low MAO group. Correlation analyses were conducted among all of the measures. The significant linear relationships between MAO and sensory gating, MAO and CO level and MAO and temperament were demonstrated. MAO activity positively correlated with the sensory gating function and negatively correlated with CO level and temperament characteristics. Finally, to explore the mechanisms of the relationship between MAO and sensory gating, the neurotransmitter systems related to MAO and sensory gating were discussed. / Ph. D.

This dissertation consists of three essays studying the economics of risky health behaviors. Essay 1 estimates the effects of Graduated Driver Licensing (GDL) restrictions on weight status among adolescents aged 14 to 17 in the U.S. The findings suggest that a night curfew significantly raises adolescents’ probability of being “overweight or obese” by 1.32 percentage points, corresponding to an increase in “overweight or obesity” rate of 4.8%. A night curfew combined with a passenger restriction increases this rate by 5.8%. Overall, I estimate that nearly 16% of the rise in “overweight or obesity” rate among teenagers aged 14 to 17 in the U.S from 1999 to 2015 can be explained by the presence of the GDL restrictions. In addition, the restrictions reduce teenagers’ exercise frequency while increasing their time spent watching TV, which may help to explain the adverse effects on obesity. Essay 2 exploits the effects of the Graduated Driver Licensing (GDL) restrictions on youth smoking and drinking. It finds that being subject to minimum entry age, a learner stage, or only a night curfew has no statistically significant effect whereas, interestingly, a night curfew combined with a passenger restriction reduces youth smoking and drinking. The estimated effects become more statistically significant and larger in magnitude in the medium run, which is in line with the addictive nature of these substances. Essay 3 investigates the underlying causes of suicide. It uses data from the U.S. at the county level and the primary methodology is a two-level Bayesian hierarchical model with spatially correlated random effects. The results show that the significant effects of observable factors on suicides found by earlier research may partially stem from excluding small area effects and time trends, without controlling for which the true contribution of unobserved propensities and time trends can be hidden within observable factors. Most importantly, a lot can be learned from unobserved yet persistent propensity toward suicide captured by the spatially correlated county specific random effects. Resources should be allocated to counties with high suicide rates, but also counties with low raw suicide rates but high unobserved propensities of suicide.