Award Date

1-1-2008

Degree Type

Thesis

Degree Name

Master of Arts (MA)

First Committee Member

Daniel N. Allen

Number of Pages

86

Abstract

There is significant overlap in the symptom presentation and cognitive impairment found in individuals with bipolar disorder with psychotic features and in those with some subtypes of schizophrenia. Due to this overlap, debate regarding the existence and nature of a relationship between these disorders has been an ongoing and complicated one. Some continue to view these disorders as they are conceptualized in the current psychiatric diagnostic manual, as distinct and categorical in nature. Others have proposed an "affective-psychotic spectrum" with schizophrenia lying at one end of this spectrum, non-psychotic affective disorders lying at the opposite end of the spectrum, and schizoaffective and psychotic bipolar disorders falling near the middle of the spectrum. To better understand the relationship between these disorders, some studies have compared the neurocognitive profiles of bipolar disorder and schizophrenia. Because neurocognitive abilities are highly heritable and under strong genetic influence, deficits in these abilities can serve as trait markers or endophenotypes for bipolar disorder, as well as for schizophrenia. An overlap in the neurocognitive deficits found in these disorders may therefore implicate similar genetic vulnerabilities; Relatively few studies have compared the neurocognitive deficits found in individuals with bipolar disorder with psychotic features with those found in individuals with bipolar disorder without psychotic features. These studies strongly suggest that among individuals with bipolar disorder, those with psychotic features experience greater working memory impairment than do those with no history of psychotic features. In that working memory deficits have repeatedly been found in schizophrenia and other psychotic disorders, working memory deficits may serve as endophenotypes for psychosis in general, and the identification of such markers could provide important insight into whether bipolar disorder and schizophrenia are discrete conditions or fall along a continuum of severity. Identification of working memory deficits in bipolar disorder with psychotic features would thus provide some support for a continuum of rather than discrete conceptualization of these disorders; In this study, we will use Baddeley and Hitch's working memory model to investigate and interpret differential deficits in working memory processes in bipolar disorder with psychotic features and bipolar disorder without psychotic features. Taking into account the results of previous research, it is hypothesized that a significantly greater amount of impairment will be found by way of lower performance scores in bipolar individuals with psychotic features as compared to bipolar individuals without psychotic features on measures designed to assess working memory systems. Largest group differences are expected to be found on measures of central executive and visuospatial sketchpad function, with smaller differences expected on measures designed to assess phonological loop function.

Keywords

Bipolar; Deficits; Disorder; Marker; Memory; Psychosis; Psychotic; Trait; Working

Controlled Subject

Clinical psychology; Cognitive psychology

File Format

pdf

File Size

1.41 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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