<p>Drug addiction and behavioural sensitization are associated with reorganization of mesolimbocortical circuitry, which we have attempted to model with glutamatergic-based long-term potentiation (LTP) in the medial prefrontal cortex (mPFC). The objective of the experiments was to examine the effects of dopamine-1 (01) and dopamine-2 (02) receptor family specific agonists and antagonists on LTP in the mPFC in the chronic in vivo preparation using fullyawake, freely-moving rats. Male Long-Evans rats were surgically implanted with stimulating electrodes into the corpus callosum and recording electrodes into the mPFC. Subjects were systemically administered a drug together with high frequency stimulation for the induction of LTP. The rats treated with the 0 1 receptor agonist A68930 (OAmg/kg/ml) showed LTP levels equal to those in the saline LTP group. The 0 1 receptor antagonist SKF83566 (0 . 15m~,/kg/ml) blocked the expression of LTP, and instead induced significant long-term depression. The 02 receptor antagonist sulpiride (3, 6, and 12mg/kg/ml) significantly decreased LTP, compared to the control group, in a dose-dependent fashion. The O2 receptor agonist quinpirole (0.125, 0.25, and 0.5mg/kg/ml) significantly increased LTP, compared to the control group, in a dose-dependent fashion. The O2 receptor agonist also induced behavioural sensitization, the intensity and frequency of which was positively correlated with the LTP effect. This is the first iii work to show that glutamatergic-based LTP in the mPFC is positively modulated by 02 receptors in the chronic in vivo preparation, and behavioural sensitization is, in turn, modulated by LTP induction. As O2 receptor-rich neurons are located largely in mesencephalic nuclei that, in turn, project to the mPFC, the 02 effects may be indirect. This plasticity modulation needs to be more deeply explored to determine its relationship to disorders, such as psychostimulant addiction and schizophrenia that are known to be due to dysregulated dopamime and glutamate function in the mesencephalon and mPFC.</p> / Doctor of Philosophy (PhD)

<p>Current public health initiatives recognize that obesity is increasing to epidemic proportions in developed countries. In keeping with the view of obesity as a developmental, progressive condition, targeting childhood factors that predict increases in body mass index (BMI) may result in the development of more effective prevention interventions. To date, prospective studies of child-onset psychopathology and adult overweight in representative community samples are limited by short duration of follow-up into adulthood and an inability to make psychiatric diagnoses. Where available, childhood data has been analyzed together with adolescent data, such that it is difficult to disentangle the relationship between early psychological distress and adult overweight in these developmentally heterogeneous groups. The main objective of this thesis is to examine the relationship between childhood and adolescent symptoms of (i) Depression (ii) Attention Deficit Hyperactivity Disorder [ADHD] and (iii) Conduct Disorder [CD] with adult overweight, in a large, prospectively followed, community sample of Canadian children.</p> <p><strong> </strong>This thesis includes the 1,992 children aged 4-11 years and 1,302 adolescents aged 12-16 years who participated in the Ontario Child Health Survey (OCHS), a provincially funded, prospective cohort study of the psychiatric and general child health of a representative sample ofOntario community children undertaken in 1983 with follow-up assessment in 2000. Data are collected from multiple informants; psychiatric disorders are determined by a combination of parental, youth and teacher self-report and interviewer-administered measures. BMI is a derived variable determined from self-reported height and weight in 2000. Multiple regression analyses are undertaken to examine the association of child and adolescent mental illness with adult overweight, after controlling for the effects of age, sex, socioeconomic status, parental psychiatric history and, among the adolescent subgroup, cigarette smoking and alcohol use.</p> <p>Adults with a history of depression, ADHD or CD identified in childhood have increased body mass (BMI = 27.2 kg/m², 27.7 kg/m², and 27.9 kg/m², respectively) compared to their nonaffected peers (BMI= 24.8 kg/m²). Children who experienced increased depressive symptoms (among boys) and CD symptoms (boys and girls) are at greater risk for future weight gain than children with fewer symptoms. Adolescent girls with Depression or Conduct Disorder are heavier in adulthood than their psychologically healthier peers. Although ADHD was initially found to be associated with adult overweight, this relationship is accounted for by the effect of conduct disturbance, regardless of child sex.</p> <p>This thesis suggests that psychopathology in childhood and adolescence predicts increased adult body mass in a large community sample ofOntarioyouth. In childhood, boys with depressive symptoms and boys and girls with disruptive behaviour are at particular risk. Among adolescents, girls with greater depressive symptoms or conduct disturbance are at increased risk of future weight gain. Research examining the trajectories of children with depressive and externalizing disorders is needed to understand the mechanism of the relationship between these disorders in childhood and eating behaviours in adulthood.</p> / Master of Science (MSc)

<p>This thesis presents research examining the impact circadian rhythm disturbances experienced in bipolar disorder (BD) have at two levels of investigation. First, circadian rhythm disturbance is studied with regard to quality of life in individuals with BD. The results of an analysis investigating the impact of self-reported circadian rhythm disturbance on quality of life (QOL) show circadian rhythm is strongly associated with poor QOL in patients with BD, independent of severity of depressive symptoms, sleep disturbance and use of sleep medications. Next, the impact of circadian rhythm disturbance on oxidative stress was studied. Oxidative stress has previously been implicated in BD, yet no studies have investigated the relationship between these systems in the context of the disorder. We demonstrate that circadian rhythm disturbance is related to increased lipid peroxidation in BD patients, which is not seen in controls. This study provides a basis for further investigation of the links between oxidative stress and circadian rhythms in the pathophysiology of BD. Taken together, these results provide evidence that circadian rhythms have a widespread impact on two separate aspects of BD: personal sense of well being and a biological marker of oxidative stress. These novel findings contribute to the mounting evidence indicating circadian rhythm disturbance as one of the core features of BD, and an important target for treatment.</p> / Master of Science (MSc)

This study examined parenting style variables in predicting college students’ depression symptoms. Participants were 989 college students who participated in the first wave of the Spit for Science project (Dick et al., 2011). This study described the prevalence of depression symptoms, including the percentage of the sample endorsing various depression symptoms, and the frequency depression scores were elevated at multiple time points. A hierarchical multiple regression was conducted to examine whether two dimensions of parenting style, Autonomy Granting and Parental Involvement, would interact in predicting depression symptoms in the Junior year. The present study demonstrates that parenting style predicts a small but significant amount of variance in depression symptoms, after controlling for demographic characteristics, and these variables interact in producing their effect. Overall, findings suggest that depression symptoms are common and parenting style is relevant in understanding such symptoms.

Using the internet to meet dating partners is increasingly popular and may have ramifications that are not yet fully realized. Although many dating sites have been operating for years, new online dating platforms continue to draw millions of new users. By using a large sample of people who use online dating platforms (n=1,286) we identified similarities and differences in what motivates people to use geosocial apps and dating sites. Motivations previously considered in the literature were supported and brought together in a single theory driven confirmatory factor analysis for each type of dating platform. A motivation to seek amusement was a latent factor unique to geosocial app use. Implications for researchers, clinicians, and dating platform users and developers may include helping users be better matched to others who have similar motivations to improve the online dating experience.

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