Award Date

5-1-2012

Degree Type

Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

First Committee Member

Daniel N. Allen

Second Committee Member

Jefferson Kinney

Third Committee Member

Murray Millar

Fourth Committee Member

Merrill Landers

Number of Pages

85

Abstract

There is increasing controversy regarding the distinction between schizophrenia and bipolar disorder as separate diagnostic categories because these disorders share many features in common. These and other findings suggest that bipolar disorder and schizophrenia may be better conceptualized along a continuum or within more homogeneous subsets of affective, psychotic, and mixed symptomatology.

Dopamine dysregulation has been found in schizophrenia and bipolar disorder, particularly those that experience psychosis during the acute phases of their bipolar illness. Dopamine has been found to play a role in reward and reward learning. Recently, research has found that individuals with schizophrenia experience deficits in reward learning, particularly negative feedback learning.

The current study examined accuracy on the first four cards of the Wisconsin Card Sorting Test as well as the use of negative and positive feedback on these initial trials in controls, bipolar with and without psychosis, and schizophrenia. Results indicate that controls and bipolar disorder without psychosis perform significantly better than the schizophrenia group with regard to ability to utilize feedback and learn the task. However, bipolar disorder with psychosis performed neither significantly better nor worse than any other group on the first two cards analyzed, but by card 4 performed at the same level as the control and bipolar without psychosis groups, which was significantly better than the schizophrenia group. Analysis of the use of positive feedback found no difference among the groups in their ability to utilize positive feedback. Use of negative feedback, on the other hand, was significantly different among groups on cards 2 and 4. Post hoc analyses demonstrated that the SZ group performed significantly worse than the controls on both cards 2 and 4 and significantly worse than the bipolar without psychosis on card 2. No other significant differences were found among the groups on use of negative feedback. Results replicate those previously found with regard to individuals with schizophrenia's impaired ability to effectively utilize feedback to learn a task. Contrary to expectations, this deficit was not found in individuals with bipolar disorder with psychosis. Results do not support the idea that those with psychosis experience the most severe deficits in reward learning. The pattern of findings in the bipolar with psychosis group may suggest that, although they are experiencing psychosis, the dopamine dysregulation is less severe thus reward learning is not being affected to the same degree.

Keywords

Dopamine; Manic-depressive illness; Schizophrenia

Disciplines

Mental Disorders | Psychology

File Format

pdf

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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