Date of Award

Fall 2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Cannon, Tyrone

Abstract

Schizophrenia and other psychotic disorders are characterized by disruptions of reality testing, most often manifest in the form of hallucinations and delusional ideation. Given that differentiating between the real from the unreal or imagined is critically dependent on episodic and associative memory, deficits in mnemonic processes have been hypothesized to be involved in the genesis of psychotic symptoms. While cognitive impairments in psychotic illness have traditionally been conceptualized as stable disease correlates that have a stronger associations with negative symptoms and functional disability, deficits in metacognition in memory, or metamemory deficits, have been hypothesized to play a crucial role in the breakdown of coherent integration of sensory and conceptual information that allows one to make sense of the world. In the present dissertation, Chapter 1 provides an overview of the basic organization of episodic memory, the nature of episodic memory impairments in psychotic illness, and current theories regarding the role and time course of metamemory impairment in the pathogenesis of psychotic illness. Chapters 2 through 4 report on a set of studies that interrogate whether the severity of metamemory impairments increases through the course of psychotic illness, the specificity of metamemory impairments to psychotic illness, and neural correlates of metamemory in psychotic illness. In Chapter 2 we leveraged data from four separate psychiatric samples representing three phases of illness: individuals in the clinical high-risk state, first-episode patients, and patients who are chronically ill with schizophrenia-spectrum disorders. We examined whether there are increasing levels of metamemory impairment across increasing phases of illness. We found evidence of increasing severity of impairment between phases of illness, as well as putative evidence of longitudinal change related to conversion/continuity of symptoms versus functional remission in the CHR sample. In Chapter 3, we examined metamemory functioning in individuals with chronic schizophrenia as compared to patients with bipolar disorder, adults with attention deficit/hyperactivity disorder, and healthy controls. We found evidence that metamemory impairment was specifically impaired among individuals with schizophrenia, despite the bipolar group showing significant impairment in verbal memory accuracy. In Chapter 4, in an exploratory investigation of the neural correlates of metamemory impairment in psychosis, we found functional networks significantly discriminating between patients with schizophrenia and healthy controls and observed associations between functional connectivity in the cerebello-thalamo-cortical (CTC) loop and metamemory, as well as general task accuracy. However, we did not find evidence of additive or unique contributions of metamemory in predicting CTC network strength among patients, controls, or overall. These findings support the relevance of metamemory to the onset and progression of psychotic forms of mental illness, suggesting use of such indices in psychosis prediction and interventions targeting confidence-based judgement during memory retrieval. Finally, Chapter 5 critically assesses these findings within the context of current theory regarding metamemory and psychotic illness and details remaining questions for future inquiry.

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