Dementia is increasing recognized as a major problem to public health worldwide. Prevention and treatment strategies are in critical need. Nowadays, research for dementia usually featured as complex longitudinal studies, which provide extensive information and also propose challenge to statistical methodology. The purpose of this dissertation research was to apply statistical methodology in the field of dementia to strengthen the understanding of dementia from three perspectives: 1) Application of statistical methodology to investigate the association between potential risk factors and incident dementia. 2) Application of statistical methodology to analyze changes over time, or trajectory, in cognitive tests and symptoms. 3) Application of statistical learning methods to predict development of dementia in the future. Prevention of Alzheimer’s disease with Vitamin E and Selenium (PREADViSE) (7547 subjects included) and Alzheimer’s disease Neuroimaging Initiative (ADNI) (591 participants included) were used in this dissertation. The first study, “Self-reported sleep apnea and dementia risk: Findings from the PREADViSE Alzheimer’s disease prevention trial ”, shows that self-reported baseline history of sleep apnea was borderline significantly associated with risk of dementia after adjustment for confounding. Stratified analysis by APOE ε4 carrier status showed that baseline history of sleep apnea was associated with significantly increased risk of dementia in APOE ε4 non-carriers. The second study, “comparison of trajectories of episodic memory for over 10 years between baseline normal and MCI ADNI subjects,” shows that estimated 30% normal subjects at baseline assigned to group 3 and 6 stay stable for over 9 years, and normal subjects at baseline assigned to Group 1 (18.18%) and Group 5 (16.67%) were more likely to develop into dementia. In contrast to groups identified for normal subjects, all trajectory groups for MCI subjects at baseline showed the tendency to decline. The third study, “comparison between neural network and logistic regression in PREADViSE trial,” demonstrates that neural network has slightly better predictive performance than logistic regression, and also it can reveal complex relationships among covariates. In third study, the effect of years of education on response variable depends on years of age, status of APOE ɛ4 allele and memory change.

Prevalence of childhood overweight and obesity has tripled in the United States in the last 30 years, resulting in 31.8% of youth (ages 2-19 years of age) classified as overweight or obese.1,2 To date many high-intensity and medium-intensity programs have been developed and tested in efforts to ameliorate the high prevalence of childhood obesity, however there is a gap in the testing and implementation of low-intensity family-based treatments.3–7The Traffic Light Program is the only childhood obesity program that has published long-term outcomes and was developed by Epstein et. al., however it only includes children from ages 6-12. We developed an 8-week family based childhood obesity program (Healthy Hawkeye Program) to test the feasibility and efficacy of an adapted version (light intensity) of the Traffic Light Program in families of overweight and obese children. To our knowledge, this is the first study to test the efficacy of a low-intensity (21 hours) comprehensive family-based intervention specifically tailored for overweight and obese children from 6 to 17 years of age. Measures include body composition (weight, fat mass, lean body mass, body fat %, BMI, waist circumference), sedentary, light and moderate levels of physical activity (wrist-worn Generative Accelerometer), dietary quality (caloric intake, fruit/vegetable daily servings), measures of nutritional and physical activity self-efficacy, Lifestyle Behavior Checklist (LBC), Family Nutrition and Physical activity (FNPA) survey, Satisfaction with Life Scale, and the Healthy Hawkeye Program Evaluation Survey. We hypothesize that participants will improve in selected (1) health measures (weight, caloric intake, daily fruit intake, daily vegetable intake, sedentary, light, and moderate physical activity levels), (2) improve in selected theoretical constructs (self-efficacy, behaviors, environments), and (3) will find the Healthy Hawkeye Program acceptable and helpful. A total of five families were recruited and only 3 families (3 mothers, 2 male children, and 1 female child) completed the program (attended 6 of 8 weekly meetings). The very low sample size of only 3 families limited the statistical analysis. The results showed parents reduced their absolute weight by 5.6 lbs and children slightly increased by 0.1 lbs. Both parents and children decreased their daily sedentary time as well as increased their daily moderate activity. Various measures of self-efficacy, behaviors, nutrition improved among parents and children. Parents and children found the program to be acceptable and helpful.

Aim: To describe the longitudinal active joint count (AJC) trajectories in juvenile idiopathic arthritis (JIA). Methods: A retrospective cohort study at two Canadian centres was performed. The longitudinal trajectories of AJC were described using latent growth curve modeling. The association of baseline characteristics stratified by trajectory group was examined by univariate methods. Results: Data were analyzed for 659 children diagnosed with JIA between 1990/03-2009/09. A maximum of 10 years of follow-up data were included in the analysis. Participants were classified into 5 statistically and clinically distinct AJC trajectories by latent GCM. Conclusions: Using a novel longitudinal statistical method we were able to classify patients with JIA based on their pattern of AJC over time. The trajectory classes need to be examined for their relationship to important genetic and biological predictors. Identification of patterns of disease course is important in working towards the development of a clinically relevant outcome-based classification system in JIA.

Aim: To describe the longitudinal active joint count (AJC) trajectories in juvenile idiopathic arthritis (JIA). Methods: A retrospective cohort study at two Canadian centres was performed. The longitudinal trajectories of AJC were described using latent growth curve modeling. The association of baseline characteristics stratified by trajectory group was examined by univariate methods. Results: Data were analyzed for 659 children diagnosed with JIA between 1990/03-2009/09. A maximum of 10 years of follow-up data were included in the analysis. Participants were classified into 5 statistically and clinically distinct AJC trajectories by latent GCM. Conclusions: Using a novel longitudinal statistical method we were able to classify patients with JIA based on their pattern of AJC over time. The trajectory classes need to be examined for their relationship to important genetic and biological predictors. Identification of patterns of disease course is important in working towards the development of a clinically relevant outcome-based classification system in JIA.

Vehicular ad hoc networks (VANETs) provide opportunities to exchange traffic information among vehicles allowing drivers to not only adjust their routes but also prevent possible collisions. Due to the criticality of exchanged information, message authentication which will not expose the privacy of vehicles is required. The majority of current authentication schemes for VANETs depend primarily on public-key cryptography which brings extra overhead in terms of delay and requires infrastructure support for certificate verification. Symmetric-key based techniques can be more efficient, but they introduce significant key maintenance overheads. Herein, by considering the natural group behavior of vehicle communications, we propose an efficient and lightweight symmetric-key based authentication scheme for VANETs based on group communication. Expanding the protocol's flexibility, we also propose an extension which integrates certain benefits of asymmetric-key techniques. We analyze the security properties of our proposed schemes to show there applicability when there is little to no infrastructure support. In addition, the proposed protocol was implemented and tested with real-world vehicle data. Simulation results confirmed the efficiency in terms of delay with respect to other proposed techniques.

Title: Borderline personality disorder: examining trajectories of development among adolescents Background: Borderline personality disorder (BPD) tends to be highly comorbid with other disorders. In adolescence, information about the classification and development of BPD is in its early stages. There is limited empirical research available that investigates predictors of clinically significant symptom trajectories of the disorder using data collected in childhood. Given the enormous personal and societal costs associated with BPD, early detection and prevention is important. Clinical implications of this research include an improved understanding of risk factors and possible mechanisms for development of BPD symptomatology. Objectives: To identify trajectories of BPD symptomatology in a Canadian sample of adolescents (N = 703) assessed at ages 13, 14, 15 and 16, while examining predictors of trajectory group membership assessed at age 12. Methods: Data from the McMaster Teen Study was used to examine trajectories of BPD symptoms using group-based trajectory modeling. The influence of gender, depression, ADHD, family functioning and various sociodemographic variables as predictors of an individual’s group membership was tested. Chi-square, analysis of variance and multinomial logistic regression was used to analyze the data. Results: A four-group trajectory model was most robust at describing BPD symptomatology in this age group. Univariate analyses supported female gender, depression and ADHD at baseline, parental age, marital status, education, and income as significant predictors of group membership. Female gender, depression and ADHD severity at baseline were significant predictors of group membership when adopting a multivariate approach. There is a greater prevalence of girls with higher depression and ADHD scores in the high-increasing features and BPD group. Conclusion: Findings demonstrate four various developmental trajectories of BPD features. Results further the understanding of the factors associated with development of the disorder across time. / Thesis / Master of Science (MSc) / Information about the classification and development of borderline personality disorder (BPD) in adolescence is in its early stages. While evidence for similar construct validity to the adult disorder exists for adolescents, major gaps in knowledge regarding the stability in course of BPD symptoms and predictors of clinically significant symptom trajectories in this age group remain. As most clinicians will assess youth already having significant features of the disorder, early detection requires knowledge of the indicators that precede an unfavourable trajectory. This dissertation will help address these gaps by modeling trajectories of BPD symptoms in youth across ages 13-16, whilst examining factors influencing trajectory group membership.

Much research has shown that regular physical activity influences both physiological and psychological health. More specifically, physical activity positively impacts wellbeing, across physical, emotional and social wellness. Furthermore, group-based physical activity has been linked to increasing adherence to an exercise protocol as well as improving social connectedness. For college students, collegiate recreation facilities are the main providers of physical activity services and programming for the campus population to utilize. In the collegiate recreation literature, several university studies have pointed out that students who participate in their recreational facilities and programs have benefited from positive feelings of wellbeing. The purpose of this study was to investigate the impact that Virginia Tech Recreational Sports' group-based fitness programming has on Virginia Tech students' overall wellbeing. Wellbeing was defined by six dimensions: career (or sense of purpose), social, financial, community, physical and emotional. This study used a concurrent explanatory mixed methods design, composed of a brief cross-sectional survey and focus groups. This work simultaneously contributes to collegiate recreation by providing evidence that students who utilize facilities and programs have higher perceptions of wellbeing as well as highlighting suggested strategies for improvement including resource limitations and communication barriers. Finally, in terms of group fitness and wellbeing, this thesis provides preliminary evidence that those who participate in collegiate group exercise programs have higher perceptions of physical and social wellbeing. / Master of Science / Regular physical activity influences both physical and mental health. More specifically, physical activity positively impacts wellbeing, across physical, emotional and social wellness. Furthermore, group-based physical activity has been linked to increasing adherence to an exercise protocol as well as improving social connectedness. For college students, collegiate recreation facilities are the main providers of physical activity services and programming for the campus population to utilize. In the collegiate recreation literature, several university studies have pointed out that students who participate in their recreational facilities and programs have benefited from positive feelings of wellbeing. The purpose of this study was to investigate the impact that Virginia Tech Recreational Sports' group-based fitness programming has on Virginia Tech students' overall wellbeing. Wellbeing was defined by six dimensions: career (or sense of purpose), social, financial, community, physical and emotional. This study used a concurrent explanatory mixed methods design, composed of a brief cross-sectional survey and focus groups. This work simultaneously contributes to collegiate recreation by providing evidence that students who utilize facilities and programs have high perceptions of wellbeing as well as highlighting suggested strategies for improvement related to access, programs, variety and communication. Finally, in terms of group fitness and wellbeing, this thesis provides preliminary evidence that those who participate in collegiate group exercise programs have higher perceptions of physical and social wellbeing.

Il presente programma di ricerca approfondisce l’uso dell’Expressive Writing (EW) con gli adolescenti a partire da tre studi, organizzati in modo sequenziale. Lo Studio 1 indaga l’efficacia e i fattori di moderazione dell’EW con gli adolescenti tramite meta-analisi. In particolare, è stata eseguita una review quantitativa degli studi sull’EW con partecipanti in età adolescenziale, attraverso i seguenti passaggi: ricerca sistematica e codifica degli studi; calcolo degli effect size; analisi dei moderatori. Lo Studio 2 confronta sperimentalmente sugli adolescenti gli effetti a breve e lungo termine di due tipi di istruzioni di scrittura, una convenzionale (EW) e l’altra orientata cognitivamente (CEW), elaborata sulla base dei risultati della meta-analisi. Le analisi sono state finalizzate a testare gli effetti della modificazione delle consegne di scrittura sul funzionamento emotivo e sociale degli adolescenti. Lo Studio 3 consiste in un’analisi secondaria dello Studio 2 ed esplora l’esito dell’intervento in funzione delle traiettorie di cambiamento dei meccanismi cognitivi (“Self-distancing”) rilevati negli scritti, tramite Group-Based Trajectory Modeling. I risultati degli studi sono discussi in funzione delle loro implicazioni teoriche e pratiche. / The present research program aims at evaluating the use of Expressive Writing (EW) with adolescents through three studies, organized in a progressive fashion. Study 1 investigates the efficacy and moderators of EW with adolescents through a meta-analysis. The study performed a quantitative review of the EW interventions with adolescent samples, according to the following steps: systematic literature search and coding of the studies; calculation of the effect size; analysis of the moderators. Study 2 experimentally compares the short- and long-term effects of the traditional writing condition (EW) to a cognitively-oriented EW condition (CEW) on a sample of adolescents. The analyses had the objective to test the effects of altering the writing instructions on social and emotional adjustment of participants. Study 3 consists in a secondary analysis of the written essays collected in Study 2 with the intent of examining the effects of the intervention as a function of the cognitive processes (“Self-distancing”) observed during the writing sessions by means of the Group-Based Trajectory Modeling. The findings are discussed on the basis of their theoretical and practical implications.

Thesis advisor: Barbara E. Wolfe / Despite the chronicity and less than optimal outcomes of inpatient treatment (IPT) for anorexia nervosa (AN), treatment guidelines continue to reflect the common notion of one-size-fits-all and the process of weight restoration continues to be poorly understood. Weight restoration, a primary goal of IPT for AN, does not occur in isolation but rather reflects an adaptation process within internal and external environments. It is unknown whether or not there are unique patterns of change in body weight that are associated with factors identified in the existing literature as being predictors of weight gain. The purpose of this study was to explore the extent to which patterns of change in body weight existed among individuals during IPT for AN, and the relationship with factors identified in the existing literature as being predictors of weight gain (i.e., age at time of admission, admission caloric intake, percent of ideal body weight [IBW] at time of admission, body weight at time of discharge, body mass index [BMI] at time of discharge). Individuals who were diagnosed with AN and admitted to the inpatient unit of an eating disorder treatment facility in the Northeast between January 1, 2012 to December 31, 2015 were included in this retrospective, exploratory study (N = 500). Group-based trajectory modeling (GBTM) was used to identify distinct trajectories of change in body weight, and to determine the risk of being in a particular trajectory. Four distinct trajectories were identified: weight gain (n = 197), weight loss (n = 177), weight plateau (n = 82), and weight fluctuate (n = 44) groups. Significant predictors of trajectories were age, history of prior IPT for AN, admission caloric intake, body weight at time of admission and discharge, and length of stay. Results from this study suggest that a further understanding of patterns of change in body weight among individuals with AN, will help guide assessment and treatment interventions and consequently influence outcomes. Additionally, there is an opportunity to update treatment guidelines and recommendations for AN. / Thesis (PhD) — Boston College, 2016. / Submitted to: Boston College. Connell School of Nursing. / Discipline: Nursing.

The purpose of this dissertation was to expand the understanding of youth in psychiatric residential treatment facilities by using psychosocial indicators to develop subgroup profiles. Additionally, differences in treatment outcomes between subgroups and the extent to which within-treatment factors accounted for observed differences in treatment outcomes between subgroups were examined. Data were extracted from the case records of 447 youth who were served in psychiatric residential treatment facilities over a seven year span of time. A latent class analysis was used to identify and describe subgroups. A series of multivariate regression analyses were used to examine group differences in functional impairment at discharge. Next, a path analysis was used to determine if there were differences in average change in functional impairment from admission to discharge between subgroups and to test within treatment factors as potential mediators of group differences. Finally, a logistic regression was used to determine if there were differences between groups in the probability of discharging to a community-based placement or discharging to another congregate care facility. The latent class analysis revealed four distinct subgroups of youth. The analyses of treatment outcomes revealed statistically significant differences in the level of functional impairment at discharge and average change in impairment between groups. Results from the path model of indirect effects supported that within treatment factors accounted for a statistically significant proportion of the observed difference in change between groups. No differences were found in discharge placement outcomes between groups. Implications for future research, practice and policies focused on youth in residential treatment are discussed.