Abstract not available

This thesis details a continuing body of research investigating the contribution of personality to disordered eating and alcohol abuse in young women. There is growing evidence of high levels of reward sensitivity in women with both disorders, and high levels of punishment sensitivity in dysfunctional eating women. However, it is unlikely that personality alone accounts for the development of such dysfunctional behaviour. Two studies were conducted to further examine the contribution of reward and punishment sensitivity to these disorders. In the first study, 443 university women completed self-report measures of alcohol use, dysfunctional eating, reinforcement sensitivity, parental drinking, family environment and maternal eating. Reward and punishment sensitivity were better predictors of disordered behaviour than family factors, although maternal dysfunctional eating significantly increased the risk of daughters' dysfunctional eating. Punishment sensitive daughters of bulimic mothers reported the highest level of bulimic symptoms themselves. Punishment sensitivity also functioned as a partial pathway variable between family risk and disordered eating. Given the stronger contribution of personality to disordered behaviour, a second study was conducted in which 131 women completed behavioural tasks under conditions of reward and punishment. Performance on a computerised measure of punishment sensitivity was associated with greater levels of dysfunctional eating but not drinking. However, performance on a card-sorting task of reward sensitivity failed to correlate with self-reported reward sensitivity or disordered behaviour. It was concluded that an innate sensitivity to reward increases the risk of disorders characterised by strong approach tendencies, whilst high punishment sensitivity, perhaps due to a chaotic family, increases the risk of dysfunctional eating, particularly daughters of eating disordered mothers.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: N.K. Nikolova and M.H. Bakr. Includes bibliographical references (leaves 134-141). Mode of access:World Wide Web.

The primary focus of this thesis was to examine the relationship of reward sensitivity and outcome expectancies, variables traditionally associated with alcohol use, to cannabis use behaviour and to explore the relationship of affect and locus of control to alcohol and cannabis use. It was hypothesised that hazardous alcohol and cannabis use would be related to higher levels of reward sensitivity and to the endorsement of more positive outcome expectancies. It was also hypothesised that positive outcome expectancies would mediate the relationship between reward sensitivity and cannabis use, and that the relationship between reward sensitivity and both alcohol and cannabis use would be moderated by punishment sensitivity. No specific hypotheses were formulated for the relationship of negative outcome expectancies, affect and locus of control of reinforcement to substance use. A total of 465 young adults aged between 18 and 35 years completed a questionnaire which assessed substance use patterns, reward and punishment sensitivity, outcome expectancies, locus of control, and affect. Results indicated that higher levels of reward sensitivity reliably distinguished hazardous from non-hazardous alcohol and cannabis users as well as cannabis users from cannabis non-users. The relationship between reward sensitivity and substance use was partially mediated by outcome expectancies, but not moderated by punishment sensitivity. An exploratory factor analysis demonstrated a high rate of concordance between alcohol and cannabis outcome expectancies. Locus of control of reinforcement was found to be unrelated to alcohol and cannabis use behaviour. There was little commonality in the relationship of sensitivity to punishment, negative outcome expectancies, and affect to alcohol and cannabis use. The second focus of this thesis was to pilot an intervention aimed at reducing alcohol use via the challenging of expectations regarding the rewarding outcomes associated with alcohol use in a group of young adult Australian males. A three session intervention was completed by three males aged between 19 and 31 years. The results demonstrated no reduction in hazardous alcohol use or global positive alcohol outcome expectancies at the completion of the intervention program or at a 3-month follow-up. Furthermore, there was no reduction in expectancies of increased sexual interest for any of the participants at the 3-month follow-up compared to baseline, despite a reduction in these expectancies for one of the three participants at the completion of the intervention. A reduction in monthly drinking levels and in expectancies of increased confidence compared to baseline was noted for two of the three participants at the 3-month follow-up. It was concluded overall that there is consistency between the relationships of reward sensitivity and positive outcome expectancies to alcohol and cannabis use and that outcome expectancies may be a proximal mechanism through which reward sensitivity influences alcohol and cannabis use. It was further concluded that whilst causal inferences regarding the effectiveness of the intervention could not be made, the results provide some evidence for the usefulness of this treatment in changing a proportion of the studied outcomes. This potentially provides an incentive for future controlled design research in larger samples and with alternate substances.

The Behavioral Activation System (BAS) has been described as playing a central role in approach motivation and reward sensitivity (Gray, 1970). Self-report measures of BAS (e.g., Carver & White, 1994) have been used to index BAS activity, with higher scores interpreted as indicating greater BAS activity (e.g., Hundt et al., 2008). However, Beauchaine and colleagues (e.g., Brenner, Beauchaine, & Sylvers, 2005) have challenged this view, noting psychophysiological and neuroimaging evidence showing that externalizing behaviors are associated with reduced BAS functioning. Furthermore, global self-reported BAS scores are often used to index approach behavior, despite evidence that two main BAS traits, impulsivity and reward reactivity, are psychometrically distinct (Smillie et al., 2006). The present study tested a measurement model of these proposed components of BAS, as well as relationships between self-report and psychophysiological BAS indices. A large undergraduate student sample completed self-report indices (N=599) and a smaller subsample also completed psychophysiological (N=18) indices of BAS-related constructs. As hypothesized, a two-factor model with impulsivity and reward reactivity as separate, correlated constructs demonstrated better model fit than a one-factor alternative model. Associations between psychophysiological indices of BAS and indices of reward reactivity and impulsivity were mixed. Implications regarding future measurement of BAS and autonomic response to reward are discussed. / Master of Science

It is well established that methadone maintenance (MM) reduces but does not eliminate the self-administration of other illicit drugs. For those on MM, there is considerable variation in consumption patterns, route of heroin administration, additional non-opioid substances routinely administered and the clinical disorders associated with these patterns of use. While there is a large literature base documenting these phenomena, studies have been almost exclusively descriptive in nature, with little attempt to develop a theoretical model in which to understand such use. In the following thesis, a model proposed by Gray was tested, the Reinforcement Sensitivity Theory (RST). This biopsychosocial model broadly describes two action tendencies; approach (Behavioural Activation System) and avoidance or withdrawal (Flight Fight Freeze System and the Behavioural Inhibition System). The model proposes that a heightened sensitivity to punishment underlies anxiety disorders. Conversely, a heightened sensitivity to rewarding stimuli may predispose some individuals to engage in highly rewarding behaviour and is associated with conduct disorder and antisocial personality disorder. According to the Joint Subsystems Hypothesis, these personality styles are mutually dependent, whereby BIS and BAS interact to influence reward mediated and punishment mediated behaviours. Based on Gray's model, this thesis tests whether opiate dependent individuals with heightened sensitivity to punishment are more likely to use anxiolytic drugs (such as benzodiazepines), and individuals with heightened reward sensitivity will show a preference for substances that have high reward potential (such as stimulants). At time one, the participant sample (N= 120) comprised 71 males (59%) and 49 females who were opioid dependent and recruitment took place over an eight-month period in two city opioid replacement clinics. A range of measures was administered to assess substance use, mood, anxiety and the personality dimensions of reward sensitivity and punishment sensitivity, with substance use again measured at three months. Results of the first study suggested that a large proportion of the variance was accounted for by personality within the models. A total of 98 participants (81%) participated in the 12-week follow-up study. Sensitivity to punishment and reward significantly predicted drug preference. Although psychopathology symptoms were not able to moderate the relationship between personality and drug use, anxiety symptoms negatively mediated the relationship between punishment sensitivity and anxiolytic use, whereby the relationship became non-significant. In contrast, sensitivity to reward remained the strongest predictor of amphetamine use over antisocial characteristics. Individual differences were not able to predict treatment retention nor susceptibility to relapse during a 12-week initiation to a MM programme.

Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters and one input (forcing data) of the Sacramento Soil Moisture Accounting (SAC-SMA) model are analyzed by using two GSA methods: Sobol' and Fourier Amplitude Sensitivity Test (FAST). The simulations are carried out over five sub-basins within the Columbia River Basin (CRB) for three different periods: one-year, four-year, and seven-year. The main parameter sensitivities (first-order) and the interactions sensitivities (second-order) are evaluated in this study. Our results show that some hydrological processes are highly affected by the simulation length. In other words, some parameters reveal importance during the short period simulation (e.g. one-year) while other parameters are effective in the long period simulations (e.g. four-year and seven-year). Moreover, the reliability of the sensitivity analysis results is compared based on 1) the agreement between the two sensitivity analysis methods (Sobol' and FAST) in terms of highlighting the same parameters or input as the most influential parameters or input and 2) how the methods are cohered in ranking these sensitive parameters under the same conditions (sub-basins and simulation length). The results show that the coherence between the Sobol' and FAST sensitivity analysis methods. Additionally, it is found that FAST method is sufficient to evaluate the main effects of the model parameters and inputs. This study confirms that the Sobol' and FAST methods are reliable GSA methods that can be applied in different scientific applications. Finally, as a future work, we suggest to study the uncertainty associated with the sensitivity analysis approach regarding the reliability of evaluating different sensitivity analysis methods.

La prolifération des électroniques et des émetteurs radiofréquences rend de plus en plus compliqué le processus de conception des systèmes sur le plan CEM. Ce processus doit aboutir à limiter le risque d’interférences ou de défauts au niveau le plus faible notamment dans le contexte des interférences électromagnétiques intentionnelles (IEMI). Ces défauts CEM doivent alors être anticipés lors de la phase de conception. Cependant, du fait de la dispersion des valeurs prises par certains paramètres du système, la modélisation déterministe éprouve quelques difficultés à identifier le risque encouru. La mauvaise connaissance de l’effet des incertitudes associées au système, aboutit alors à prendre des marges de conception considérables conduisant à des surcoûts de fabrication. Pour cette raison, il est devenu important de prendre en compte l’impact des incertitudes des différents paramètres constitutifs d’un système (en phase de conception). Ces paramètres sont essentiellement géométriques (e.g. position de câblages) ou électromagnétiques (e.g. caractéristiques intrinsèques de matériaux). Ils influent par nature sur les performances CEM de ce système. Ces travaux de thèse portent sur l’analyse de la propagation des incertitudes relatives à ces paramètres sur des sorties de modèles de CEM. Le but visé, consiste à quantifier sous une forme probabiliste, le risque de défaut d’un système contenant de nombreux paramètres incertains. Ce type d’étude statistique devrait également permettre, via des analyses de sensibilité, des stratégies de conception de systèmes « fiables » ou à moindres coûts. Dans le contexte des applications visées, les approches dites « fiabilistes » et la méthode dite de « stratification contrôlée », ont été identifiées comme intéressantes, du point de vue de l’analyse d’événements extrêmes. Dans un premier temps, nous nous sommes consacrés à la transposition des méthodes fiabilistes dans un contexte CEM. Ces techniques permettent de quantifier la probabilité de défaillance d’un système, définie comme le dépassement d’un seuil de risque, et renseignent, via une analyse de sensibilité locale, sur les paramètres clés à ajuster. Dans un second temps, nous nous sommes intéressés à la méthode de stratification contrôlée, non appliquée à ce jour à notre connaissance en CEM. L’objectif de cette approche consiste à estimer un quantile extrême de la réponse d’intérêt d’un modèle rigoureux, via l’utilisation d’un modèle simple beaucoup moins coûteux en termes de temps de calcul. Ce processus permet d’accélérer l’obtention d’observations extrêmes, nécessaires à l’estimation du quantile recherché. Les deux techniques ont été mises en oeuvre sur un problème complexe dans un contexte IEMI, pour estimer la probabilité d’occurrence d’événements d’interférences extrêmes. Elles ont permis de dégager des tendances similaires, quant à l’importance de certains paramètres d’entrée incertains sur les événements rares. Les deux méthodes, bien appliquées, pourraient constituer un apport considérable en matière de conception CEM. / The proliferation of electronic and radio frequency transmitters makes more complicated the system design process on the EMC point of view. This process should lead to limit the risk of interferences or defects to lowest level particularly in the context of intentional electromagnetic interferences (IEMI). Therefore, these EMC defects have to be anticipated during the design stage. However, due to the dispersion of the values taken by some parameters of the system, the deterministic modeling presents some difficulties to identify the involved risk. The poor knowledge of the uncertainties effect associated with the system, leads then to take important design margins at the price of additional costs of manufacturing. For this reason, it has become important to take into account the impact of uncertainties of the various constituent parameters of a system (at the design stage). These parameters are essentially geometric (e.g. position of wirings) or electromagnetic (e.g. intrinsic characteristics of materials) ones. They influence by nature the EMC performance of this system. This thesis work deals with the analysis of the propagation of uncertainties of these parameters on EMC model outputs. It aims at quantifying in a probabilistic form, the default risk of a system containing numerous uncertain parameters. This type of statistical analysis should also allow through sensitivity analyses, design strategies of “reliable” systems or at lower cost. In the context of targeted applications, the so-called “reliability approaches” and the “controlled stratification” method have been identified as interesting from the point of view of the analysis of extreme events. Firstly, we are dedicated to the transposition of reliability methods in an EMC context. These techniques are used to quantify the probability of failure of a system, defined as the probability of exceeding a threshold of risk. They inform through a local sensitivity analysis, on the key parameters to adjust. Secondly, we have focused our work on the controlled stratification method, not yet applied in EMC as far as we know. The objective of this approach is to estimate an extreme quantile of the interest response of a rigorous model, using of a much cheaper simple model in terms of computation time. This process allows to speed up the identification of extreme observations required for the estimation of the researched quantile. Both techniques have been applied on a complex problem in an IEMI context, to estimate the probability of occurrence of extreme interference events. They have revealed similar trends as regards to the importance of some uncertain input parameters on rare events. Both methods, properly applied, could provide a significant contribution in terms of EMC design strategy.

Features of impulsivity underlie multiple psychological disorders. The body of work examining impulsivity has largely focussed on self-report measurement and has incorporated psychological constructs without reference to the broader biological factors that may influence impulsive behaviour. Two studies were conducted to examine whether environmental stress and genetic status associated with dopaminergic and serotonergic function (DRD2, ANKK1 and 5HT2AR genotypes) were predictive of dimensions of impulsivity and risky behaviour (alcohol use). The two studies used a multi-method approach in a non-clinical community sample of young adults (aged 17-25 years). Dopamine is integral to the two leading theories of impulsive personality, Gray's Reinforcement Sensitivity Theory and Cloninger's Psychobiological model of personality. Dopamine plays a crucial role in reward reinforcement circuits in the brain. The A1 allele of the ANKK1 gene (also referred to as TaqIA of the DRD2 gene region) and the CC genotype of the C957T polymorphism of the DRD2 gene have both been associated with reduced D2 dopamine receptor density in key structures linked to brain reward. In addition, a strong body of evidence implicates their involvement in a number of clinical disorders associated with impulsivity. Serotonin function has also been associated with impulsivity in Cloninger's theory and there is also evidence of associations of two polymorphisms of the 2A serotonin receptor gene (5HT2AR T102C and -1438A/G SNPs) with impulsivity. Acute and chronic forms of stress are also important correlates of impulsive behaviour and the two studies directly examined the relationship between genotype, stress and impulsivity. Study 1 (N=180) utilised a cross-sectional design and examined interactions between these polymorphisms and chronic stress exposure on key impulsivity dimensions of reward sensitivity, Novelty Seeking and rash impulsiveness. Participants completed psychological questionnaires measuring chronic stress, dimensions of impulsivity, mood and substance use and provided mouth swab samples of buccal mucosal cells for DNA analysis. The study confirmed the association between A1 and CC allelic status and chronic stress being associated with harm avoidance and sensitivity to punishment. This suggests a role for both dopamine and background stress in impulsive behaviour. Study 2 (N=73) built upon this questionnaire research in the laboratory by utilising experimental psychological paradigms of impulsive behaviour and experimentally manipulating acute stress. Study 2 employed a mixed experimental design with a sub-sample of those studied in the cross-sectional sample. These behavioural paradigms included pre- and post- stress induction administration of the Card Arranging Reward Responsiveness Objective Test (capturing behavioural approach in the presence of reward cues, presumed to reflect reward sensitivity) and post-induction delay discounting and response inhibition measures. Study 2 confirmed the role of one of the two dopamine-related polymorphisms, with those with A1+ allelic status demonstrating lower reward responsiveness prior to rest or stress induction, which was overcome in the second administration of this task, independent of environment. A1+ allelic individuals also demonstrated significantly poorer response inhibition independent of stress, further confirming the association between A1+ allelic status and impulsivity. Those with CC allelic status showed an increase in reward responsiveness only in the stress induction condition. Together, results from the two studies inform the development of a multidimensional model of impulsivity that captures gene-environment influences on discrete aspects of impulsive personality and behaviour. Further refinement of this model may lead to the development of more effective customised prevention and treatment interventions for clinically disordered impulsivity. The implications of dopaminergic systems and stress in understanding disorders such as ADHD and substance dependence are discussed.

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