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dc.contributor.authorMacKenzie, Lynn
dc.date.accessioned2019-09-10T11:08:08Z
dc.date.available2019-09-10T11:08:08Z
dc.identifier.urihttp://hdl.handle.net/10222/76392
dc.description.abstractSevere mental illness (SMI) includes schizophrenia, bipolar disorder and severe and chronic major depressive disorder. SMI typically onsets early in the lifespan and causes significant impairments in functioning. Cognitive function has been proposed as a potential neurodevelopmental indicator of risk for development of SMI. However, the relationships between cognition and risk for onset of SMI in individuals at familial risk are not fully understood. This thesis aimed to investigate cognition in individuals at familial and clinical risk for SMI. In study 1, I examined cognition in 360 children and youth, and found that offspring of parents with psychotic SMI performed significantly worse on overall cognition, verbal intelligence, verbal working memory, processing speed, verbal learning and memory, verbal fluency and sustained attention. Sons and daughters of parents affected with non-psychotic SMI performed significantly worse than controls on verbal intelligence, visual memory and decision-making. The findings of study 1 indicate that mild cognitive impairment may be a marker of transdiagnostic familial risk for any form of SMI. Additional deficits in verbal cognition, verbal memory, verbal fluency, processing speed, and sustained attention may be markers of familial risk for psychotic SMI. In study 2, I investigated cognition as a potentially important indicator of neurodevelopmental disturbance and its association with propensity to experience psychotic symptoms in a cohort of 295 youth, 71 of whom reported definite psychotic symptoms. After accounting for age, sex and familial clustering, psychotic symptoms were associated with worse performance in overall cognition, verbal intelligence, visual memory, decision-making, spatial working memory, and set shifting. In study 3, I investigated cognitive performance as a potential etiological mechanism in the development of severe mental illness. In a 6-year longitudinal cohort of 309 youth, I found that onset of SMI was predicted by reduced overall cognitive performancce, verbal intelligence, and sustained attention. These findings indicate that deficits in cognitive ability are associated with familial risk for psychotic SMI, propensity to experience psychotic symptoms, and new onsets of severe mental illness diagnoses in offspring. Impairments in overall cognition may be indicators of risk and targets for pre-emptive early interventions.en_US
dc.language.isoenen_US
dc.subjectSchizophreniaen_US
dc.subjectbipolar disorderen_US
dc.subjectmajor depressive disorderen_US
dc.subjectsevere mental illnessen_US
dc.subjectpsychotic symptomsen_US
dc.subjectoffspringen_US
dc.subjectyouth at-risken_US
dc.subjectfamilial risken_US
dc.subjectoffspring of affected parentsen_US
dc.subjectneurodevelopmenten_US
dc.subjectcognitionen_US
dc.subjectcognitive performanceen_US
dc.titleCognition in individuals at familial and clinical risk for severe mental illnessen_US
dc.date.defence2019-08-26
dc.contributor.departmentDepartment of Psychology and Neuroscienceen_US
dc.contributor.degreeDoctor of Philosophyen_US
dc.contributor.external-examinerDr. Kristen Woodberryen_US
dc.contributor.graduate-coordinatorDr. Aaron Newmanen_US
dc.contributor.thesis-readerDr. Sherry Stewarten_US
dc.contributor.thesis-readerDr. Kim Gooden_US
dc.contributor.thesis-supervisorDr. Rudolf Uheren_US
dc.contributor.ethics-approvalReceiveden_US
dc.contributor.manuscriptsNot Applicableen_US
dc.contributor.copyright-releaseNot Applicableen_US
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