Medicine and Health Sciences Commons^™

Data-Driven Neuroanatomical Subtypes In Various Stages Of Schizophrenia: Linking Cortical Thickness, Glutamate, And Language Functioning, Liangbing Liang

Electronic Thesis and Dissertation Repository

The considerable variation in the spatial distribution of cortical thickness changes has been used to parse heterogeneity in schizophrenia. We aimed to recover a ‘cortical impoverishment’ subgroup with widespread cortical thinning. We applied hierarchical cluster analysis to cortical thickness data of three datasets in different stages of psychosis and studied the cognitive, functional, neurochemical, language and symptom profiles of the observed subgroups. Our consensus-based clustering procedure consistently produced a subgroup characterized by significantly lower cortical thickness. This ‘cortical impoverishment’ subgroup was associated with a higher symptom burden in a clinically stable sample and higher glutamate levels with language impairments in …

Incidence Of Cancer And Stage At Diagnosis Among People With Recent-Onset Psychotic Disorders, Jared C. Wootten

Electronic Thesis and Dissertation Repository

Evidence on cancer incidence in people with psychotic disorders, compared to the general population, is equivocal, although those with psychotic disorders so have more advanced stage of cancer at the time of diagnosis. The objective of this thesis was to compare cancer incidence and stage at diagnosis for people with psychotic disorders, relative to the general population. Our systematic review did not observe a significant difference in overall cancer incidence among people diagnosed with psychotic disorders (RR = 1.08, 95% CI: 1.00 to 1.16), however people with psychotic disorders were more likely to be present with advanced stage cancer at …

Risk Stratification For Treatment Decisions In People At Ultra-High Risk For Psychosis: A Cost-Effectiveness Analysis, Olajumoke Marissa Ologundudu

Electronic Thesis and Dissertation Repository

People with psychotic disorders have long-term negative health outcomes and contribute large health system costs. Intervening among those at ultra-high risk (UHR) for psychosis may prevent or mitigate risk for psychotic disorder; however, it is unclear if we should treat all UHR individuals or only those above a certain risk threshold. The objectives were to systematically review the literature on the cost-effectiveness of UHR programs, and to conduct an economic evaluation of a risk stratification strategy, where treatment decisions are based on the probability of transitioning to psychotic disorder. Our systematic review found that UHR programs are potentially cost-effective. The …

Functional Magnetic Resonance Spectroscopy In First-Episode Schizophrenia: Measuring Glutamate And Glutathione Dynamics At 7-Tesla, Peter Jeon

Electronic Thesis and Dissertation Repository

Schizophrenia is a neuropsychiatric illness without known etiology or cure. Current efforts for symptom treatment still seem to leave a large portion of affected individuals without proper symptom management, with those experiencing symptom relief still having to wrestle with potential side-effects from medication trials. There has been growing evidence suggesting that glutamate and glutathione abnormalities hold major roles in development and manifestation of schizophrenia symptoms.

Magnetic resonance spectroscopy (MRS) provides a non-invasive means to observe in-vivo brain chemistry, including glutamate and glutathione. By adding a functional component to an MRS paradigm (fMRS), such as the color-word Stroop task, it is …

Inviting Hallucinatory Percepts During Speech-Listening To Detect Cognitive Changes In Early Psychosis, Ana-Bianca Popa

Electronic Thesis and Dissertation Repository

Treatment outcomes for people with schizophrenia are more favourable if treatment starts early in the course of the disorder. Current detection methods lack specificity and do not make use of cognitive markers. We presented individuals experiencing a first episode of psychosis (FEP) and matched control participants with acoustically degraded meaningful and matched nonsense sentences to examine the degree to which people reported words that were not actually presented. Intrusion errors were counted when reported words were unrelated to words in the original sentence. Intelligibility (measured as words reported correctly) did not differ between groups but intrusion errors were more frequent …

Cannabinoid Transmission In The Basolateral Amygdala Modulates Prefrontal Cortex And Ventral Hippocampal Activity, Brian J. Pereira

Electronic Thesis and Dissertation Repository

The cannabinoid system is important for maintaining neuron-to-neuron communication within the mammalian brain. One of the most commonly used substances to alter the cannabinoid system is cannabis. Individuals who are exposed to cannabis report having dissociable effects; both positive and negative. High amounts of THC have been commonly associated with the negative effects of cannabis, whereas CBD can be used to counter these. Pre-clinical evidence suggests that the combination of the two compounds can produce a therapeutic benefit for individuals who are susceptible to the effects of THC. The present study investigates whether the combination of THC+CBD can prevent electrophysiological …

Measuring Brain Serine With Proton Magnetic Resonance Spectroscopy At 3.0 Tesla, Homa Javadzadeh

Electronic Thesis and Dissertation Repository

Proton magnetic resonance spectroscopy (MRS) non-invasively measures regional human brain chemistry in vivo, providing concentration estimates for several metabolites in a pre-selected region of interest. MRS has been applied to investigations of disease-related metabolic and neurochemical alterations in schizophrenia since the early 90’s.

The objective of this research is to implement a metabolite-selective MRS method to quantify endogenous concentrations of human brain serine. Serine is a naturally-occurring amino acid and an important co-modulator of the N-Methyl D-aspartic Acid (NMDA) glutamate receptor. Glutamate abnormalities have been implicated in the pathophysiology of schizophrenia, especially its so-called negative and cognitive symptoms, which can …

Addressing Very Short Stimulus Encoding Times In Modeling Schizophrenia Cognitive Deficit, Colleen D. Cutler

Electronic Thesis and Dissertation Repository

It is well known that encoding times in persons with schizophrenia are longer than those of normal controls. Neufeld and others have argued that this is the consequence of additional subprocesses being executed during the encoding process in the case of schizophrenia. In general they expressed an encoding time as the sum of $k^{\prime}$ independent exponentially-distributed subprocesses, each executed with rate $v$. A troubling consequence of their application of this model to real data was that under some circumstances some individuals appeared to encode instantaneously. This was accommodated in Neufeld et al. by placing a Poisson distribution on …