Award Date

8-1-2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Committee Member

Daniel Allen

Second Committee Member

Michelle Paul

Third Committee Member

Bradley Donohue

Fourth Committee Member

Jennifer Keene

Number of Pages

97

Abstract

Serious mental illnesses (SMIs) often have an onset early in life and go on to produce disability and functional impairment, which require ongoing supportive services and loss of productivity. Bipolar disorder (BD) and schizophrenia (SZ) are two of the most common SMIs. BD and SZ differ in their pattern of neurocognitive performance, which suggests differences in the severity of functional impairment between the illness groups. Within these psychiatric illness groups, subgroups may also be identified using cluster analysis. Evidence points to heterogeneity in functional outcomes in BD and SZ, yet very little research has assessed for subgroups based on functional capacity within these psychiatric groups. To examine this manner, the current study utilized archival data from ongoing research studies conducted in the Neuropsychology Research Program (NRP) laboratory at the University of Nevada, Las Vegas (UNLV). The sample consisted of 250 adults with a primary diagnosis of BD (n = 129) or SZ (n = 71) and healthy controls (HC; n = 50). The primary measure of functional capacity was a performance-based task called the University of California, San Diego (UCSD) Performance-Based Skills Assessment (UPSA; Patterson et al., 2001). Distinct functional capacity profiles in BD and SZ were identified using cluster analysis. Results demonstrated that clusters were differentiated primarily by pattern of performance in the clinical groups and there were differences between the psychiatric groups in the number of clusters identified. A three-cluster solution was optimal for BD, whereas a five-cluster solution best captured heterogeneity in SZ. Normal functioning clusters were identified in both clinical groups. The SZ group demonstrated greater overall impairment compared to BD and healthy controls. For adults with BD or SZ, cluster membership was associated with differences on a number of outcome variables, supporting the external validity of the cluster solutions. The current findings provide support for the idea that there is substantial heterogeneity in functional abilities for individuals with SMIs with differential impact on functional capacity. Identifying subgroups based on functional capacity may have implications for tailored treatment approaches and prognosis considerations.

Keywords

Bipolar disorder; Cluster analysis; Functional outcomes; Schizophrenia; Serious mental illness; UPSA

Disciplines

Mental and Social Health | Psychology

File Format

pdf

File Size

1900 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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