Date of Award

Spring 1-1-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

First Advisor

Vijay A. Mittal

Second Advisor

David J. Miklowitz

Third Advisor

Angela Bryan

Fourth Advisor

Monique LeBourgeois

Fifth Advisor

Mark Whisman

Abstract

Sleep dysfunction is a pervasive and distressing symptom in schizophrenia, yet little is known regarding the extent to which problematic sleep is present prior to the onset of illness, or how sleep impairment may relate to symptoms in at-risk individuals. The current thesis explores two primary aims. First, I examined whether adolescents at ultra high-risk (UHR; n = 33) for psychosis display increased sleep dysfunction (duration, continuity, latency, efficiency, total movement counts, disturbances, quality) on subjective (Pittsburgh Sleep Quality Index; PSQI) and objective (actigraphy) measures compared to healthy controls (HC; n = 33), and if present, how sleep disturbances relate to symptoms (positive, negative, disorganized) among UHR youth. Second, magnetic resonance (MRI) and diffusion tensor (DTI) imaging were employed to determine if neural structures (thalamus) and tracts (anterior thalamic radiations) underlying sleep function are abnormal in UHR adolescents compared to HC participants, and if so, how neural abnormalities relate to sleep impairment in UHR youth. An exploratory aim examined relationships between subjective and objective measures of sleep disturbance in UHR youth. Results indicated that UHR adolescents displayed increased latency, greater disturbances, decreased efficiency, disrupted continuity, and increased sleep movements compared to HC youth. Reduced duration, increased latency, and decreased quality predicted elevated negative symptoms in UHR youth, and decreased efficiency, disrupted continuity, and increased movements during sleep predicted increased positive and disorganized symptoms. Bilateral thalamus volume reductions were found in UHR compared to HC adolescents, and these abnormalities predicted increased latency, decreased efficiency, reduced sleep quality, disrupted continuity, and increased movements among UHR youth. There were no group differences in anterior thalamic radiation integrity; however, in UHR patients, integrity decreases predicted greater disturbances, reduced quality, decreased efficiency, disrupted continuity, and increased movements. UHR adolescents accurately reported sleep efficiency, and subjective report of disturbances predicted sleep movements. These results suggest that sleep dysfunction occurs during the pre-psychotic period, and may play a role in the developmental diathesis-stress cascade driving schizophrenia onset. In addition, the relationship of disrupted sleep to psychosis symptoms in UHR youth indicates that prevention and intervention strategies may be improved by targeting sleep stabilization in the pre-psychotic period.

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