Graduation Year

2008

Document Type

Thesis

Degree

M.A.

Degree Granting Department

Psychology

Major Professor

Cynthia R. Cimino, Ph.D.

Committee Member

Michael Brannick, Ph.D.

Committee Member

Paul Jacobsen, Ph.D.

Keywords

Movement disorders, Executive functioning, Memory, Psychological symptoms, Depression Anxiety Stress Scales (DASS)

Abstract

Depression and anxiety are common psychiatric disturbances in Parkinson's disease (PD). Past studies have demonstrated a relationship between depression and cognitive decline in PD; however, the unique influence of anxiety has not been well studied. The objective of the present study was to differentiate the unique influences of depression and anxiety on cognitive functioning in PD. Sixty-eight cognitively intact PD patients with mild to moderate motor disease severity completed self-report questionnaires and neuropsychological tests. Two hierarchical regression analyses were conducted with executive functioning performance as the criterion variable, and two additional hierarchical regression analyses were conducted with memory performance as the criterion variable. Depression and anxiety, as measured by the Depression Anxiety and Stress Scales (DASS), served as predictors for all analyses. Each set of analyses examined the amount of added, unique variance accounted for by anxiety when depression was entered as the first predictor, and also examined the amount of added, unique variance accounted for by depression when anxiety was entered as the first predictor.

It was found that depression significantly predicted delayed recall memory performance when entered as the first and second predictor. In contrast, anxiety did not significantly predict performance on any of the cognitive measures. Two DASS subscales assess for the physical symptoms of anxiety, and these subscales were not significantly correlated with any cognitive variables. However, the DASS subscales tapping into non-physical aspects of anxiety were significantly associated with several cognitive variables. Patients may have endorsed physical symptoms of anxiety due to the symptoms associated with PD, and not as a result of the genuine presence of anxiety. This could have masked a potential relationship between anxiety and cognitive functioning in PD, and suggests that specific components of anxiety may be associated with cognition in PD. Future adaptation of the DASS may be necessary to differentiate the unique influences of depression and anxiety in PD patients.

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